Questions and answers about HIV PrEP 

'Trans' or 'transgender' is a broad umbrella that refers to people whose gender identity is different from the one they were assigned at birth - for example, an individual who was assigned male at birth but now identifies as a woman. 'Cis' or 'cisgender' refers to people whose gender identity matches the one they were assigned at birth. 

In general in this document, statements about recommendations for 'women' are inclusive of cisgender and transgender women. Similarly, recommendations for 'men' are inclusive of cisgender and transgender men. However, as many research studies - especially earlier ones - almost exclusively recruited cisgender people, some statements about research data usually relate only to cisgender men or women, unless otherwise stated. 

Non-binary people - an umbrella term for anyone who does not identify with the gender binary of male or female - represent a broad church of people with various gender identities (including non-binary, genderqueer, demigender, and so on), sex characteristics, and relations to gender affirming treatments like gender affirming hormone therapy. Accordingly, it can be difficult to provide prescriptive advice for, for instance, a non-binary person who has been assigned male at birth (for instance, this person may or may not be using hormones to affirm their gender). If seeking guidance for a non-binary person, it is recommended doing so with consideration of their relevant characteristics - specifically, the genitals that they use for sex and whether or not they are using gender affirming hormones. For instance, guidance for trans men would apply, most of the time, to a non-binary person assigned female at birth who is using testosterone as part of their gender affirmation (as these are assumed to be, roughly speaking, biomedically equivalent).

For some people, including some trans men, the term 'front hole', rather than 'vagina', is the preferred term for their genitals. In addition, the term 'frontal sex', rather than 'vaginal sex', is often preferred. Whenever the vagina and vaginal sex are mentioned in this briefing, this includes the front hole and frontal sex, unless otherwise stated. The term ‘neovagina’ is used to refer to a vagina that has been surgically constructed. 

This document uses the abbreviation GBMSM - this means gay, bisexual and other men who have sex with men. Unless otherwise stated, this includes trans men, cisgender men, and non-binary people assigned male at birth.

Pre-exposure prophylaxis (PrEP) is an HIV prevention tool  that uses antiretroviral drugs to protect HIV-negative people from HIV infection. People take PrEP when they are at risk of exposure to HIV, in order to lower their risk of infection. 

PrEP is highly effective in preventing the sexual transmission of HIV, as long as the drugs are taken as directed. However, PrEP does not prevent other sexually transmitted infections or pregnancy. 

PrEP is one of several ways in which antiretroviral drugs can be used to prevent HIV transmission:

• ARVs taken by an HIV-negative person before (and then after) possible exposure to HIV: Pre-Exposure Prophylaxis (PrEP)

• ARVs taken by an HIV-negative person after possible exposure to HIV: Post-Exposure Prophylaxis (PEP)

• ARVs taken by an HIV-positive person during pregnancy, childbirth, breastfeeding and chestfeeding

• ARVs taken by an HIV-positive person: treatment as prevention or Undetectable = Untransmittable (U=U)

A person who does not have HIV takes enough PrEP for there to be high levels of the PrEP drugs in their bloodstream before any exposure to HIV. If exposure occurs, PrEP  stops the virus from entering cells and replicating. This prevents HIV from establishing itself and the person remains HIV negative. 

The antiretrovirals which are currently used as PrEP were chosen because they have limited side-effects, have few problems with drug resistance and remain in the body for a relatively long time.

Historically, guidelines have included precise eligibility requirements for PrEP, but it has become clear that this restrictive approach discourages the use of PrEP by a more diverse range of people. 

In contrast, the most recent UK guidelines (chapter 5) take a broad approach to PrEP eligibility: PrEP should be offered to people, regardless of their gender or sexual orientation, who would benefit from a reduction in HIV risk. Importantly, this includes anyone who requests PrEP themselves. 

The guidelines also include people whose HIV risk is likely to be greater than that of the background UK population – this may be because they belong to a group with an elevated HIV risk (for example, recent migrants, or GBMSM), because of individual behaviours (for example, lots of sex without condoms), due to injecting drug use (for example, when equipment is shared) and due to reduced autonomy in sexual health (for example, being in a coercive relationship). These are just a few examples and the list is not exhaustive.

Furthermore, PrEP is recommended for people who are likely to have condomless sex with someone whose situation could be included in the previous paragraph. For example, someone who is monogamous but whose partner has multiple partners would be eligible for PrEP.

One situation in which PrEP is not recommended in the guidelines is when a person’s only possible exposure to HIV is from a person living with HIV who has an undetectable viral load – as there is zero risk of HIV transmission. 

However, some people who might be perceived as being at lower risk of acquiring HIV might have anxiety about HIV infection. For instance, someone in a monogamous relationship might be concerned that their partner is having sex with other people. Even though PrEP is not a ‘treatment’ for HIV anxiety and HIV anxiety may not be ‘rational’, it needs to be acknowledged that some individuals might want to take PrEP because they feel it gives them more control over HIV prevention or because it helps them to relax and enjoy sex. As a reminder, the guidelines support providing PrEP to anybody who requests it for themselves.

A person's risk of HIV infection is not constant. It is likely to vary over time as circumstances change. For example, moving to a new city or the break-up of a stable relationship may start a period of higher risk. These are sometimes called “seasons of risk”. 

People may decide to stop using PrEP for a variety of reasons. For example, they may have changed their sexual behaviour, their HIV-positive partner may have achieved an undetectable viral load, or a relationship may have become mutually monogamous. Support for PrEP users should include recognition of situations that may involve exposure to HIV and education on safe stops and restarts of PrEP. 

When stopping oral PrEP, doses still need to be taken for a few days after the last possible HIV exposure. (See question 30).

There are five different types of PrEP which have been proved to be effective in clinical studies – at the time of writing, two of these are available on the NHS. There are two types of PrEP tablets (often called ‘oral PrEP’ because they are taken by the mouth), two types of PrEP injections and one vaginal ring.

The original and most widely used type of PrEP is a tablet which contains two anti-HIV drugs, tenofovir disoproxil (TDF) and emtricitabine (FTC). The original manufacturer sold this as Truvada, but most people now take tablets produced by generic manufacturers. In the UK and most other countries, the vast majority of people taking PrEP are taking this combination, which is often called TDF/FTC.

It is mostly often taken daily, but it’s possible to take several doses before and after sex and still be protected. (See questions 29, 30, 31 and 32).

There is an alternative PrEP tablet which contains tenofovir alafenamide (TAF) and emtricitabine (FTC). The brand name is Descovy and it is still under patent in the UK, which means that the NHS can’t use generic versions (although cheaper generic versions are available to buy online - see question 26). This alternative tablet, which we refer to as TAF/FTC in this briefing, is usually used by adolescents and people who have concerns about their kidney or bone health. (See questions 6, 16, 38 and 39).

At the time of publication (February 2025), TAF/FTC was approved for use as PrEP in around 15 countries, including the United Kingdom, United States, Canada, Australia and Poland, but not in other parts of the European Union. 

The first PrEP injection to be approved is long-acting cabotegravir (CAB-LA), sold under the brand name Apretude. Injections are given every two months and need to be given by a healthcare professional. (See questions 27, 36 and 41).

At the time of writing, cabotegravir was approved in around 20 countries, including the UK. But although the UK Medicines and Healthcare Products Regulatory Agency (MHRA) has authorised cabotegravir as a safe and effective form of PrEP, the National Institute for Health and Care Excellence (NICE) rejected the first application for cabotegravir. NICE must assess whether cabotegravir is cost-effective at its current price, but had concerns about the way the pharmaceutical company had analysed its cost-effectiveness. The Scottish Medicines Consortium (which has a similar role to NICE in Scotland) approved cabotegravir for use by NHS Scotland in February 2025.

Lenacapavir is an alternative PrEP injection, taken every six months. Trial results were announced in 2024 and showed extremely high efficacy. Drug regulators in the US and Europe may approve lenacapavir sometime in 2025; lenacapavir is not yet available for PrEP in any country. (See questions 27, 37 and 41).

There is also a vaginal ring. Like a contraceptive ring, it is a flexible silicone ring that is placed in the vagina and releases the anti-HIV drug dapivirine over the course of a month. The ring has only been tested with cisgender women.

The ring was approved by the European Medicines Agency in 2020, but this was through a procedure which enables the agency’s regulatory expertise to be used to grant a licence for a device intended to be used in lower-income countries. The ring is available in several African countries, but there are currently no plans to market it in Europe or other high-income countries. For this reason, there is less information on using the ring in this document than for the other types of PrEP.

Long-acting forms of PrEP, including injections, the vaginal ring and (possibly in the future) weekly or monthly pills, may have important advantages for some people. Many people struggle to remember to take a pill every day or do not have the daily routines that support daily pill taking. For people who want or need to keep their use of PrEP private, having a supply of pills with them risks unwanted disclosure. As a result, long-acting forms of PrEP may be more convenient and easier to take regularly. 

The two PrEP tablets contain different formulations of the drug tenofovir. The most widely used tablet contains tenofovir disoproxil (TDF), whereas the other tablet contains tenofovir alafenamide (TAF).

Both are in fact ‘prodrugs’, which means that they are inactive until the human body processes them and converts them to their active form. TAF produces higher levels of the active drug in HIV-susceptible immune cells than TDF. This means TAF can be given at lower doses, resulting in less drug exposure for the kidneys and bones.

TAF/FTC does have advantages for people with kidney or bone issues, which become more common as people get older. On the other hand, there is a greater risk of weight gain with TAF/FTC (see questions 38, 39 and 40). However, for the vast majority of people taking PrEP, the small differences between the tablets are not important. Both are highly effective and well tolerated. 

TAF/FTC is only available on the NHS as branded Descovy, which is much more expensive than generic TDF/FTC (however, generic formulations of Descovy can be bought online (see question 26)). For this reason, UK guidance restricts the use of TAF/FTC to individuals who have a clinical reason to specifically need it. 

This includes:

• People with reduced kidney function (eGFR below 60 ml/min). (See question 38)

• People who have osteoporosis (low bone mineral density) or have been assessed as having a high risk of a bone fracture. (See question 39)

• People under the age of 18 – this is because adolescence is a critical period for bone growth and development. (See question 16)

For the detail of policy on TAF/FTC, see NHS England’s prescribing policy and chapter 6 of the recent BASHH/BHIVA guidance.

TAF/FTC has not been licensed in the rest of Europe because health officials there had indicated that they would not recommend prescribing TAF/FTC to large numbers of people. In contrast, TAF/FTC has been heavily marketed in the US and is widely prescribed there.

As noted in question 3, UK guidelines now take a broad approach to PrEP eligibility: PrEP should be offered to people, regardless of their gender or sexual orientation who would benefit from a reduction in HIV risk. 

In terms of the specifics of how PrEP is taken, there has also been an effort to make the UK recommendations as consistent as possible between all genders. In many cases, the most recent guidelines from BASHH and BHIVA take a different approach to other international guidelines, many of which recommend fewer options, or more complex regimens, to women (both cisgender and transgender) than to cisgender gay and bisexual men. This is often because of differences in expert opinion on the impact of anatomical and hormonal differences on the risk of HIV acquisition. (See question 11).

So, in most cases, BHIVA and BASHH advise that PrEP can be used in the same way by all groups of people. However, there are some exceptions.

The UK guidelines recommend that all groups of people can start oral PrEP with a double dose (two pills) 2-24 hours before potential exposure. However, the guidance on stopping PrEP (how many doses of PrEP to take after the last risk) varies according to the type of risk that the person is exposed to. After the last episode of sex, some people will only need to take two more daily doses, while others will need seven more daily doses (see question 30). 

In practice, this means that using PrEP to cover short periods of possible exposure to HIV – such as a weekend – is less practical, but not impossible, for cisgender women and members of some other groups. (See question 32).

UK guidelines support taking TDF/FTC during pregnancy, breastfeeding, chestfeeding or when trying to conceive. There is less data on TAF/FTC and cabotegravir in these situations than on TDF/FTC, but the guidelines remain supportive. (See question 43).

TDF/FTC, TAF/FTC and cabotegravir are all licensed for adolescents and adults weighing at least 35kg (five and a half stone). (See question 16).

Concerning TAF/FTC, the license from the UK Medicines and Healthcare products Regulatory Agency (MHRA) and consequently the official label that comes with each bottle state that it is not licensed as PrEP for those who need protection during receptive vaginal (frontal) sex. The original research evaluating TAF/FTC, completed in 2019, only involved cisgender gay and bisexual men and transgender women. This problem has been addressed by including a group of cisgender women taking TAF/FTC in the PURPOSE 1 study, which is better known as a study of injectable lenacapavir. The key findings were released in July 2024, but the data on TAF/FTC have not been fully analysed yet. In any case, the recent guidelines from BASHH and BHIVA support the use of TAF/FTC by all population groups (a different position to other international guidelines – see question 11).

The vaginal ring has only been tested in cisgender women, during vaginal sex (it provides no protection during anal sex). The World Health Organization state that for trans women with a neovagina, the ring’s effectiveness is unknown and more research is needed. They suggest that trans men and other gender diverse individuals assigned female at birth who are not using gender-affirming hormones can use the ring for frontal sex. While there is no data on its effectiveness when used alongside gender-affirming hormones, they say that they do not expect any drug interactions.

It’s important for people to find an HIV prevention method which suits them and works for them, so when more options are available, it is expected that people will try different methods out. Also, people’s circumstances and needs change, so their preferences may change too. For example, people may want to switch to a method which is more discreet, or one which does not require as many clinic visits.

People should get advice so that they switch methods at the right time and have the right tests. For example, people switching from injectable cabotegravir would normally start a new method eight weeks after their last injection. The tests to take are likely to be similar to those for someone starting PrEP for the first time (e.g. HIV tests).

The most widely used PrEP tablet contains two drugs: tenofovir disoproxil (TDF) and emtricitabine (FTC). It is unusual for people to have intolerance to emtricitabine, but if they do, other types of PrEP may be more suitable. 

In addition, two clinical trials with cisgender heterosexual men and women tested PrEP tablets which only contained tenofovir disoproxil. As the results in these studies were comparable to those of tenofovir disoproxil and emtricitabine, UK guidelines support the use of tenofovir disoproxil by heterosexual cisgender men and women who cannot take emtricitabine.

However this drug has not been tested in other populations (such as GBMSM or transgender women), so its use is not supported. In general, the evidence base for the combined pill of tenofovir disoproxil and emtricitabine is much stronger than for solo tenofovir disoproxil.

Several different types of PrEP, using different drugs and different delivery methods, are in development. They include:

• A version of the vaginal ring that can be used for three months at a time

• A version of injectable cabotegravir that can be taken every four months, and another that can be injected subcutaneously

• A once-a-month oral PrEP pill. Specifically, a phase IIa trial is testing different monthly doses of a drug called MK-8527. Additionally, pharmaceutical companies are researching several other drugs to be taken weekly or monthly as HIV treatment, which may provide future PrEP options

• A pill that contains both TDF/FTC and an oral contraceptive, and a vaginal ring that contains both dapivirine and a contraceptive

• An ‘insert’ that is placed in the vagina or rectum, where it dissolves within a few hours. The insert contains two PrEP drugs (TAF and elvitegravir)

It’s important to note that not all of these will pass the necessary tests and make it through the development process. Also, the excellent results for lenacapavir, announced in 2024, may slow investment in new methods – policy makers and pharmaceutical companies may feel that a new PrEP product will struggle to compete with such a convenient and effective form of PrEP.

Guidelines are tailored to the specific healthcare context of each country. In settings with limited healthcare resources, guidelines may prioritise a broad, public health-focused approach. This involves delivering a simplified package of care to reach as many people as possible. In contrast, in countries with more resources, care may be more personalised, allowing for more detailed assessments and tailored treatments for each individual.

In countries with publicly funded health systems, such as the UK, cost-effectiveness and equitable access to care often play a major role in shaping guidelines. This can lead to  more caution about adopting costly treatments. On the other hand, in countries with healthcare systems driven by profit-making companies, guidelines might focus more on the availability of a wide range of options, sometimes at a higher cost.

Another factor is how different guideline committees approach evidence. Some countries may only base their recommendations on data from randomised control trials, which are seen as the highest standard of evidence. Others may take a more pragmatic view, incorporating expert opinion or a broader array of data sources. They may be especially likely to do so when there is no relevant data from randomised control trials, given that researchers have often failed to include all relevant populations in these studies. For example, there have been no studies testing event-driven PrEP in cisgender women or cisgender heterosexual men, but the UK guidelines make recommendations on this, drawing on other types of data. (See questions 29 and 32).

Also, current guidelines in many countries were written a few years ago, before more recent evidence became available.

Since there are multiple ways of analysing and summarising the data, the following estimates (except for lenacapavir) all come from a recent World Health Organization publication:

• When used as directed, oral TDF/FTC can reduce the risk of HIV acquisition through sexual transmission by more than 90% and pharmacological evidence suggests by up to 99%. These figures compare taking PrEP as directed with taking no PrEP

• Evidence suggests that, when used correctly and consistently, the vaginal ring reduces HIV risk by over 50%, and some analyses have found a higher effectiveness. These figures compare using the ring with no use of a ring or other type of PrEP

• Evidence suggests that, when administered correctly and on schedule, injectable cabotegravir may reduce the risk of HIV acquisition by 79%, compared with the use of oral PrEP

• The World Health Organization has not yet synthesised data from studies of injectable lenacapavir. However, a study in cisgender women showed that it reduced the risk of HIV acquisition by 100% (compared to no PrEP) and also by 100% (compared to oral PrEP). In a study primarily recruiting gay and bisexual men and transgender people, it reduced the risk of HIV acquisition by 96% (compared to no PrEP) and by 89% (compared to oral PrEP)

It’s important to note what each type of PrEP was being compared with. Most studies of oral PrEP and of the vaginal ring compared it with a placebo (in other words, a dummy product). By the time of injectable PrEP studies, it was known that oral PrEP was safe and effective, so it would have been unethical not to provide it to study participants who did not receive the injectable product. The cabotegravir data therefore shows the extra effectiveness, in addition to that of oral PrEP – in so far as study participants actually used it.

In interpreting these data, it’s also worth thinking critically about who was recruited to these studies. Some of the key oral PrEP studies, conducted a decade ago, recruited a large number of people who were keen to get hold of oral PrEP, which at the time was an innovative product and unobtainable outside of a research study. 

By the time of the injectable PrEP studies, oral PrEP was readily available in clinics. We can speculate that people who were happy with oral PrEP would have had little motivation to join an injectable PrEP study, whereas people who were keen to use injectable PrEP were more likely to take part. Indeed, adherence to oral PrEP was low in these studies.

This may help explain why, even though oral PrEP is highly effective when it is taken, cabotegravir and lenacapavir both appear to be so much more effective in these research studies.

(Also see question 19).

There has been a small number of cases where people with complete PrEP adherence have acquired HIV. These are often described as “HIV breakthroughs”. Of about one million people taking PrEP worldwide, fewer than 20 HIV breakthroughs have been reported in scientific journals. 

Almost all cases of PrEP failure are thought to have occurred through having sex with someone who had both detectable levels of HIV and a form of HIV that had developed resistance to the drugs in PrEP. Being exposed to HIV that has already developed this type of resistance is rare, especially considering that someone with undetectable levels of HIV cannot transmit the virus, regardless of whether they have a form of HIV that’s resistant to the drugs in PrEP. One study found that in about 4000 people with HIV in Seattle, less than 0.3% had detectable levels of HIV with resistance to emtricitabine and tenofovir.

Cases of PrEP failure have been reported with both oral PrEP containing TDF/FTC, with injectable cabotegravir and with injectable lenacapavir (but not with oral PrEP containing TAF/FTC, perhaps because fewer people use it). These cases are extremely rare but generate a lot of scientific, media, and community attention. 

The biggest risk factor to acquiring HIV while taking oral PrEP is not taking the medication consistently, resulting in inadequate drug levels in the body. If this is what is thought to have happened, it is not considered a case of PrEP failure.

However, it’s very difficult to determine whether someone acquired HIV with adequate levels of PrEP drugs in their system – because samples would need to have been taken very close to when the infection occurred. 

In the 20 or so cases reported in scientific journals, doctors were confident that the person had been taking PrEP consistently, because their adherence had been established via hair testing or pill counts, or they had been monitored as part of their participation in a study. In cases involving injectable PrEP, the dates that injections were given were clear from medical records.

When taken consistently, as prescribed, oral PrEP can be highly effective at preventing HIV transmission for cisgender women. This was clearly demonstrated by the Partners PrEP study, conducted in sub-Saharan Africa. 

Nonetheless, a number of PrEP studies and PrEP programmes with cisgender women have had less encouraging results than has been seen elsewhere with gay and bisexual men. Major reasons for this are lower levels of adherence and social barriers to consistent use of PrEP.

For many years, it was believed that anatomical differences were also important. We do know that different concentrations of the two main PrEP drugs (TDF and FTC) are achieved in rectal and vaginal tissues. Also, after stopping oral PrEP (or missing a few days of doses), drug levels decline more quickly in vaginal tissue.

However, the importance of anatomical differences is increasingly being questioned. One recent analysis found that lower drug levels in vaginal tissue did not help explain the level of effectiveness seen in cisgender women – drug levels in blood cells were much more relevant. And these are the same in men and women.

This science on this topic is complex and is not settled. Our understanding of this issue is likely to evolve in the coming years. For more information, see this aidsmap article.

Two studies conduced with cisgender women in African countries have shown very high efficacy with two types of injectable PrEP, cabotegravir and lenacapavir. It’s clear that in these settings, most women found injectable PrEP much easier to take consistently than oral PrEP. 

There is a lack of evidence on PrEP’s effectiveness for frontal and vaginal sex in trans and non-binary people. See the next question for more on this.

There is data about the effectiveness of oral PrEP in relation to trans women, but limited information for trans men or non-binary people. Many of the studies that included trans women didn’t include enough trans participants to have reliable conclusions on efficacy.

Nonetheless, data from the open-label extension of the iPrEx study suggest that oral PrEP containing TDF/FTC is highly effective for trans women when it is taken as prescribed. Among 151 trans women who have sex with men, nobody with drug levels equivalent to two to three pills a week or more acquired HIV. However, three trans women with drug levels equivalent to less than two pills a week did acquire HIV. 

Other studies have compared other types of PrEP with TDF/FTC, so provide information for more than one type of PrEP. In the DISCOVER trial which compared daily TAF/FTC with TDF/FTC, none of the 74 trans women taking part acquired HIV. PrEP drug levels did not differ between participants who were using or not using gender affirmative hormones.

Trans women were well represented in the HPTN 083 study, with 304 receiving TDF/FTC and 266 receiving injectable cabotegravir (overall, 12.5% of participants were transgender or gender non-conforming). Efficacy results were similar to those of cisgender gay and bisexual men in the study. Among the 13 trans participants who acquired HIV, none had evidence of high levels of adherence to either TDF/FTC or cabotegravir injections. Cabotegravir concentrations did not differ between participants who were using or not using gender affirmative hormones.

The PURPOSE 2 study of lenacapavir was the first PrEP trial to intentionally include trans men (43 participants) and gender nonbinary people (209 participants), as well as trans women (478 participants). Overall, 22% of all participants were trans or non-binary. At the time of writing, efficacy results have not been broken down by gender identity, but showed that overall, lenacapavir reduced HIV infections by 96% compared with no PrEP, and by 89% compared with oral TDF/FTC. 

In several studies, adherence to oral PrEP was low amongst trans women. One factor contributing to lower adherence in trans participants may be either a fear of, or lack of information about drug-to-drug interactions between PrEP and gender-affirming hormone medications. Many trans people will prioritise hormone use over other health concerns, including HIV. (For more on drug interactions, see question 48. For more information about the interactions with gender-affirming hormones, see question 51).

More research is needed on each of the following points:

• PrEP effectiveness in trans men or non-binary people. However, individuals whose only risk factor is anal sex could be expected to have similar levels of protection from PrEP as cisgender GBMSM, if achieving similar levels of adherence

• PrEP effectiveness for frontal and vaginal sex in trans and non-binary people

• Event-based dosing in trans people (see question 51)

In the UK, both types of PrEP tablets (TDF/FTC and TAF/FTC) and cabotegravir injections are each licensed to be used by adolescents over the age of 12 who weigh at least 35 kg. Guidelines from BASHH and BHIVA support the use of PrEP by young people from the age of 15 in accordance with their reported risk.

Those guidelines add that for people under the age of 18, TAF/FTC should be offered instead of TDF/FTC. Young people who have started to take TAF/FTC are advised to continue on it until the age of 20. Similarly, NHS England’s policy on reimbursement of PrEP (which restricts TAF/FTC to specific groups of patients with a clinical need for it), supports the use of TAF/FTC by people under the age of 18.

The reason for this is that one of the drugs contained in the most widely used PrEP tablet is tenofovir disoproxil (TDF), which can have an impact on bone mineral density during adolescence, when the bones are still growing and developing. Although any loss of bone mineral density appears to be reversible after stopping TDF/FTC PrEP, this is a key issue for clinicians to monitor. (See question 39).

TAF/FTC, cabotegravir and lenacapavir do not have the same impact on bone mineral density.

The lenacapavir studies recruited people aged 16 and over, so it is likely to be approved for this age group.

In several studies of adolescents taking PrEP, the main challenge has been low levels of adherence to the medication. Guidelines from BASHH and BHIVA recommend that young people on PrEP should be offered additional support and monitoring to optimise adherence.

UK guidelines support the use of PrEP by people who inject drugs and who share needles. In most countries, the number of PrEP users whose primary HIV risk is through sharing drug injection equipment is very small. However, in the US, there is a greater effort by some in the public health community to encourage the use of PrEP by people who inject drugs.

People who use drugs may be exposed to HIV during sex and also through sharing equipment used to inject drugs. PrEP could have a different effectiveness in relation to these two transmission routes. While there is no reason to think that PrEP does not prevent sexual transmission in people who inject drugs, its effectiveness when the risk is through sharing equipment is less clear. 

Only one randomised PrEP study has been done with people who inject drugs, in Thailand. It showed that tenofovir disoproxil was partially effective in preventing HIV infection in this population. Although the study aimed to assess the effectiveness of PrEP in preventing transmission through injecting drug use, it's possible that the effectiveness seen was in part due to preventing sexual transmission.

Another difficulty with the study was that proven harm reduction interventions, including needle/syringe exchange, were not provided. The study's results are difficult to apply to settings where people who inject drugs have a much lower risk of acquiring HIV because harm reduction interventions are provided.

By testing participants' blood for the presence of oral PrEP drugs, researchers have attempted to estimate the number of PrEP doses they have actually taken. They have then looked at the number of HIV infections in people with different levels of adherence. 

For example, in the iPrEX OLE study of gay and bisexual men and transgender women using TDF/TFC, most infections occurred in people taking less than two doses a week, with none occurring in individuals taking four or more doses. The researchers calculated the following levels of protection:

• Less than two doses a week: 44% fewer infections (credible range: -31 to 77%)

• Two or three doses a week: 84% fewer infections (credible range: 21 to 99%)

• Four or more doses a week: 100% fewer infections (credible range: 86 to 100%)

In an analysis of three studies with cisgender women, there was a similar pattern:

• Two doses a week: 59% fewer infections (credible range: 30 to 96%)

• Four doses a week: 84% fewer infections (credible range: 52 to 99.8%)

• Seven doses a week: 96% fewer infections (credible range: 73 to 100%)

The 'credible range' shows the researchers' uncertainty about what the true level of protection is. For example, four doses a week in the first study was thought to provide protection of somewhere between 86% and 100%. 

Taken together, it appears that four or more doses a week appears to be highly effective.

The alternative PrEP tablet contains TAF rather than TDF. These are different formulations of the same drug (tenofovir) and a key difference is that when TAF is taken, there are much higher levels of tenofovir in peripheral blood mononuclear cells (rather than in the blood), and this is thought to be important for PrEP’s efficacy. The implications are that TAF/FTC may be more potent and more ‘forgiving’ of missed doses than TDF/FTC. In other words, TAF/FTC is likely to remain effective with fewer weekly doses than TDF/FTC.     

We don’t yet have equivalent data for injectable cabotegravir or lenacapavir, but given the long gaps between planned injections, it is likely that missing a single injection would have a considerable impact on effectiveness. In the studies, over 90% of injections were given on time. (See questions 36 and 37).

This figure is often quoted in conversations around PrEP. Some people may hear it and think it means that HIV will be transmitted in one sexual encounter out of 100. Others may assume it means a 99% reduction in per-contact risk, which is already relatively low in the case of HIV. 

Instead, it means that in the IPREX study, gay and bisexual men and transgender women who took 7 doses of PrEP a week had a 99% lower risk of becoming HIV-positive than people who took a placebo pill (credible range 96 – >99%). If, for example, among 2000 people taking a placebo pill 100 people acquired HIV, then 1 person (100 minus 99) would acquire HIV taking PrEP.

But it’s almost important to look at the credible range, as was discussed in the last question. Given uncertainties, it’s possible that 96% rather than 99% is the true figure. If that is the case, in the same hypothetical example, 4 people would acquire HIV taking PrEP.

(For more on effectiveness, see question 12).

As a reminder of the difference between PrEP and PEP: 

• You start to take pre-exposure prophylaxis (PrEP) before you are exposed to HIV and continue to take it for as long as you need it, to protect against infection. PrEP tablets contain two drugs

• You take post-exposure prophylaxis (PEP) after you have been exposed to HIV, for a fixed period of one month. It is best to start PEP within 24 hours of exposure to HIV, but certainly within 72 hours. PEP contains three drugs (usually including tenofovir and emtricitabine, the two drugs in PrEP tablets)

There should be strong links between PrEP and PEP programmes. This should help current or former PrEP users to access PEP if they need it, and for people taking PEP to consider transitioning to PrEP at the end of their course.

If an oral PrEP user has missed some doses, the extra protection offered by PEP may be helpful. However, it’s worth remembering that four days of oral PrEP a week is thought to be enough to protect against HIV. (See question 18). This means that someone who generally takes daily PrEP consistently but has missed one or two doses does not need to panic.

Missed doses are more of a concern when someone has recently started PrEP (because there may not be much PrEP medication already in their body) or when multiple doses have been missed.

The recent guidance from BASHH and BHIVA (chapter 8) provides detailed advice on how to handle these kinds of situations. In general, when someone realises that they have missed a dose, they should take a double dose (two pills) of their PrEP. After that, they should continue to take a single PrEP dose each day. People who have recently started PrEP or have missed multiple doses should also urgently contact clinical services to ask if they need to take a course of PEP. If they do take PEP, the regimen will be their usual PrEP tablet plus an additional drug, taken daily for one month. It’s therefore important that they don’t stop taking PrEP if there is any delay in getting clinical advice – the PrEP will still provide some protection.

The advice above mentioned that PEP might be recommended if multiple doses have been missed, but what counts as ‘multiple doses’? For someone who needs protection during anal sex (either insertive or receptive), PEP might be advised if they had last taken PrEP over 7 days ago but had had sex within the last 3 days (72 hours). For someone who needs protection during insertive vaginal sex (for example, a cisgender man), the same time frame applies. For someone who needs protection during receptive vaginal sex (for example, a cisgender woman), PEP might be advised if they had last taken PrEP over 3 days ago but had had sex within the last 3 days (72 hours).

There is specific advice for people who are using ‘event driven’ PrEP but are late for or forgot their first dose after sex. In other words, they began a course of PrEP with the double dose before sex, but missed the single dose 24 hours later. As long as no more than 48 hours have elapsed since sex, they should take the dose they missed and then continue with PrEP as planned. If it is more than 48 hours after sex, they should take the dose they missed and get urgent clinical advice about a possible course of PEP.

As this advice is complex, the following key information may be more practical for sharing with PrEP users:

• If you have been exposed to a possible HIV risk when you haven’t been taking PrEP, or haven’t taken enough PrEP, contact a health worker  to discuss whether you might need PEP

• Take a double dose of PrEP as soon as possible (if you still have some). This will provide some protection while you are trying to access PEP

• PEP is more likely to work if started within 24 hours of possible exposure. It doesn’t work if started after more than 72 hours.

• In the UK you can get PEP from a sexual health clinic or from A&E if the  clinic is closed. A&E departments are open 24 hours a day, 7 days a week

Ever since it first started to be used in the UK (and in most other high-income countries), PrEP uptake has been highest among cisgender GBMSM. Arguably, most PrEP services continue to offer a model of care which suits (some) GBMSM well, and little tangible action has been taken to ensure equity in PrEP provision and support. 

Key groups in the UK who are currently underrepresented among PrEP users are Black African & Black Caribbean communities; queer communities of colour (including Black, Brown, Latin American and other communities); migrant communities; trans and/or non-binary people; people who inject drugs; people who sell sex; young gay and bisexual men; heterosexual women who may be at risk of HIV and who are not included above; and men who have sex with men, but who don’t identify as gay or bisexual. Geographical barriers may compound the issues affecting people from these groups who live in rural or semi-urban locations.

The most recent UK guidelines (chapter 3) make suggestions for how health providers can address PrEP inequity at each stage of the PrEP care continuum.

Settings (where people learn about, access and use PrEP). Identify and address barriers in these settings, including the physical space; the experience of new users and marginalized communities. Collect data on exclusion and lack of connections with other services.

Access Consider and address accessibility, travel, affordability, service adequacy and privacy at all stages. Consider offering multiple ways to access a service (e.g. online booking, walk-in services, etc.) and measures to reduce geographical barriers in rural areas (e.g. STI and kidney tests provided by local health services).

Awareness Include marginalized communities who may benefit from PrEP but may not be aware of it by working with community stakeholders to address community-specific needs and provide inclusive and appropriate PrEP information tailored to specific communities. Integrate PrEP information and provision into existing generic services.

Knowledge Encourage and enable dialogue within and across groups, communities and institutions so that people can adapt and incorporate health-related information into their social norms.

Uptake (candidacy). Work to ensure that potential PrEP users are aware that they may be candidates for PrEP and address barriers to candidacy (e.g. concerns about PrEP suiting their life circumstances). Ensure that health providers’ risk assessments are inclusive.

Retention (adherence and support). Develop targeted strategies to support PrEP initiation and sustained use that work for marginalized groups with higher rates of discontinuation such as those with lower socio-economic status, substance use and younger people (e.g. medication storage in pharmacies, follow-up appointments in community settings).

Arguably, the key reason is that equitable provision of PrEP has not been a priority in NHS policy. There has been institutional inertia and a lack of imagination. 

Nonetheless, there are some challenges and barriers which need to be worked around. 

Currently, some GP surgeries, pharmacies, contraceptive clinics and young people’s health services do provide some sexual health services. They provide what are known as level 1 or level 2 sexual health services, which include testing and treatment of some uncomplicated STIs for some groups of people, vaccinations, condom provision and HIV testing, as well as referrals. However, they do not prescribe or supply antiretroviral drugs, whether for PEP, PrEP or HIV treatment – this is left to ‘level 3’ services, which are specialist sexual health and genitourinary medicine clinics.

As a consequence, other health services in the UK do not have any experience of prescribing antiretrovirals and many healthcare professionals perceive them to be complex drugs, particularly regarding drug interactions. In some other countries, primary care physicians and community pharmacists take a more active role in providing HIV treatment, so this is less of a barrier to expanding PrEP provision.

Also, many services which have been suggested as possible PrEP providers (e.g. primary care, community pharmacies) have concerns about their capacity to take on new activities. Additional funding would be needed to make provision sustainable, and there are other regulatory and logistical challenges to resolve. 

If other organisations do make PrEP available, they might only provide certain elements of the full package of services. For example, assessment and a first prescription might be handled by one service, with ongoing follow up elsewhere. Healthcare workers in more accessible settings who have less experience of PrEP might work in collaboration with clinicians at specialist services, especially for advice on complex cases.

In 2020, the HIV Commission called for PrEP to be available in GP surgeries, maternity units, termination of pregnancy services, gender clinics and pharmacies. The government committed to improving access to PrEP in settings outside sexual health services in its 2021 HIV Action Plan for England and 2024 PrEP roadmap, but these commitments, at the time of writing, have not been implemented. The most recent BASHH and BHIVA guidelines support expansion of PrEP provision, with evaluation, for example through online services, in community pharmacies, drug and alcohol services, in primary care and in community settings.

The pharmaceutical company that first develops a drug usually has a patent which gives the company exclusive rights to manufacture and sell the drug for a period of time in specific countries. After the patent expires, other companies can produce their own version of the same medication. These ‘generic drugs’ contain the same active ingredient as the branded products, and have the same safety and quality requirements. But they are sold for a much lower price, especially if several generic companies are in competition with each other.

In addition, while a medicine may be protected by patent in high-income countries such as the UK, the pharmaceutical company may have given permission to some generic manufacturers to produce the drug, usually only for distribution in low- and middle-income countries. For example, TAF/FTC is only available to the NHS as branded Descovy, but generic versions are manufactured for use in the global south. (When people buy generic TAF/FTC from online pharmacies based overseas, this is the product they are buying – see question 26).

There are huge variations in the price of different types of PrEP:

• The patent on TDF/FTC expired several years ago, so the NHS now purchases it from generic manufacturers. The ‘official’ NHS price is £54 per person a month, but experts believe that the actual price paid (after negotiation and volume discounts) is below £15

• The official NHS price for TAF/FTC (Descovy) is £356 per person a month. The patent for this combination expires in 2032, but the patent for TAF is expected to expire in 2025, which might open the possibility for generic manufacturers to produce a combination of TAF and lamivudine (3TC) – this is a very similar drug to FTC

• The official NHS price for cabotegravir (Apretude) is £1197 per injection (i.e. £599 per person a month). The patent expires around 2031

• Lenacapavir has not yet been marketed in the UK, but when sold in other high-income countries as a specialised drug for HIV treatment, the official price is around $15,000 per injection (i.e. $30,000 per person a year). The patent expires around 2037

There are some clinical reasons why someone might not be able to take PrEP, for example if they have severe liver or kidney problems.

Assuming that is not the reason why PrEP has been refused, if someone thinks PrEP would be useful for them but their clinic seems unwilling to help, you could advise them to speak to a senior doctor. They could also share the most recent BASHH and BHIVA guidelines on PrEP. These recommend that PrEP is offered to people, regardless of their gender or sexual orientation, who would benefit from a reduction in HIV risk. Importantly, this includes anyone who requests PrEP themselves. 

PrEP is also available through private prescriptions or by ordering from an online pharmacy that is based overseas. (See question 26).

The rules for access to NHS care for HIV, sexually transmitted infections and several other infectious diseases are different from the rules for access to many other NHS hospital services. People can access PrEP for free at NHS sexual health clinics in the UK, regardless of their immigration status. 

Access to PrEP, like access to all treatment at NHS sexual health clinics, is free of charge. This is the case regardless of someone’s immigration status. It also includes people who are undocumented. People should not have to share their immigration status or provide their ID to access PrEP for free. However, the clinic may take their postcode for administration purposes.

Several online pharmacies based overseas sell generic PrEP medications. Although generic TDF/FTC should be readily available through NHS services, some people prefer to purchase it themselves. For people who do not meet the relatively strict NHS eligibility criteria for TAF/FTC or struggle to access it, buying it online may be their only option. 

BASHH and BHIVA guidelines recommend that clinicians offer support, including renal monitoring, to people who are taking oral PrEP they have sourced online. Moreover, it is legal to buy and import PrEP to the UK, as long as it is for personal use. A prescription is not required. In order to show that the drugs are only for personal use, individuals are advised to buy no more than three months' worth (usually up to 3 bottles of 30 pills) at once. 

People who buy their own PrEP drugs are strongly recommended to get clinical advice and support, for example from an NHS sexual health clinic, in order to take PrEP safely. People buying PrEP drugs need the same tests as other PrEP users – regular screening for HIV, sexually transmitted infections and kidney function. See questions 28 and 45 for more information on these tests.

More detailed advice on ordering online from reputable suppliers can be found on PrEPster, IWantPrEPnow and https://www.prep.global/get-prep. It’s important for people to check that they are ordering a product which contains both tenofovir (either TDF or TAF) and emtricitabine.

BASHH and BHIVA guidelines advise that generic manufacturers of PrEP sold this way have their own quality control processes in place and meet production standards that are considered satisfactory by the World Health Organization (WHO) and the United States Food and Drug Administration (FDA). They say that there is no evidence that PrEP bought online from the major suppliers into the UK is substandard (contains lower or variable amounts of active ingredients) and that there has never been evidence of counterfeit PrEP in circulation. When people first started importing generic TDF/FTC around 2016, thorough testing showed that the drugs taken worked in the same way as branded PrEP. In 2018 PrEPster undertook independent testing of the most commonly used online sellers and found no evidence of counterfeit medicine.

The oral PrEP that can be bought online is affordable because it is produced by generic manufacturers, whose prices are set primarily for countries in the global south. The manufacturers of both cabotegravir and lenacapavir have signed voluntary licensing agreements that permit generic - and therefore cheaper - versions to be produced for use in specific countries and regions. There is potential that these generic versions could become available beyond those areas (as generic oral PrEP did) and purchased via online pharmacies. However it is not expected for these generic formulations to be available before 2027, and there are some issues which need to be taken into consideration.

Cabotegravir is an intramuscular injection. Because of the volume of drug required, it must be injected into a large muscle such as the buttocks. If the injection is not done properly (for example, the needle does not reach the muscle), drug levels would be too low to provide protection. Clinicians generally assume that self-injection is not possible (or is not desirable), but many trans people already self-inject hormones intramuscularly into the buttocks. The pharmaceutical company is testing other ways of delivering the drug (such as into the thigh), which might make self-injection easier.

Lenacapavir is a subcutaneous injection – it is injected under the skin of the stomach. Self-injection is more likely to be feasible, but has not yet been tested. 

While cabotegravir can be stored at a wide range of temperatures, lenacapavir should be kept between 15°C and 30°C. This might pose a problem for postal delivery from overseas.

 (See question 23 for information on the cost of injectable PrEP).

UK guidelines recommend the following tests should be done when starting any type of PrEP:

• An HIV test. It's important to check that the person doesn't have HIV without realising it – if they did have HIV, taking PrEP could mean they develop resistance to drugs they may need for treatment. It’s OK to start PrEP just with the results of a rapid point-of-care test (with a finger prick blood sample, not an oral fluid sample), as long as a blood sample is sent to a laboratory for a ‘4th generation’ test at the same time. Self-testing (with the result read by the person taking the test) is not considered reliable enough. People who have recently had flu-like symptoms or a rash should have them assessed by an HIV doctor, in case they could be related to a recent HIV infection (seroconversion)

• An HIV viral load can be considered for people who have possibly been exposed to HIV within the last four weeks (the window period of a 4th generation test). This could detect very recent HIV infections 

The guidelines also recommend the following tests, but these are most important for people using oral PrEP:

• Kidney function test. One of the drugs in the most widely used oral PrEP tablet (TDF) can occasionally lower kidney function (see question 38), so monitoring the health of the kidneys is essential. A blood test for creatinine is used, with the result converted to a figure called eGFR

• Hepatitis B test. This is needed because oral PrEP drugs are active against hepatitis B, whereas injectable PrEP drugs are not. For this reason, oral PrEP is considered preferable for people who have hepatitis B, but they will need additional clinical advice when they stop PrEP. (See question 44)

It is recommended that all sexually active people, regardless of PrEP use, have regular tests for sexually transmitted infections, and appropriate sexual health vaccines (see question 57). 

Medical history should be reviewed to see if there are risk factors for bone problems. Scans to assess bone mineral density are only recommended for people with risk factors. (See question 39).

Recent UK guidelines state that for people at high risk of HIV infection, starting PrEP should not be delayed while waiting for test results. People can start PrEP on the same day that they take all these tests. Clinicians should review test results as soon as possible and modify the PrEP prescription if necessary.

(See question 45 for the tests taken regularly while using PrEP).

In the recent UK guidelines, oral PrEP can be started with a double dose (two pills). This should be taken between 2 and 24 hours before sex or another possible exposure to HIV. 

This advice is the same for people who intend to take PrEP for a short or long period of time.

If people find that they get gastrointestinal side effects following the double dose (such as an upset stomach), they can take the dose as two separate tablets 6-12 hours apart. Some people find taking the pills before they go to sleep helps reduce side effects.

Doses after this are single doses (one pill). In theory they should be around the same time of day as the first dose, but after a few days PrEP users may find it helpful to adjust the time of doses to the time of day at which they will find it easiest to remember to take their pills – for example, with breakfast.

The UK recommendations on starting PrEP are different from those of some other countries. Most other guidelines recommend people to take one week of daily PrEP before possible exposure to HIV (and have sometimes recommended a longer lead-in period for cisgender women, due to anatomical differences). (See question 11).

The UK guidelines do acknowledge that the evidence for beginning with a double dose within 24 hours of possible exposure is strongest for gay and bisexual men. (This regimen was proven to be effective in the French IPERGAY study of event-based PrEP). For other populations, the recommendations are based on expert opinion and pharmacokinetic studies of how the drugs are processed and used in the body. If somebody needs extra reassurance, they can of course choose to take PrEP for several days before having sex.

It’s fine for people to take a break from PrEP if they won’t need protection from HIV for a while. However, they need to take some extra doses of PrEP after their last potential exposure to HIV (such as sex) in order to maintain protection. Some people, including cisgender women, need to take seven more doses of PrEP before stopping. The recent UK guidelines (chapter 8) make the following recommendations:

• People who need protection when they are insertive (topping) during sex – whether frontal/vaginal, neovaginal or anal – can take a single dose daily for two days after the last risk, and then stop

• People who need protection when they are receptive (bottoming) during anal sex can take a single dose daily for two days after the last risk, and then stop

• People who need protection when they are receptive during frontal/vaginal or neovaginal sex can take a single dose daily for seven days after the last risk, and then stop

• People who need protection during injecting drug use can take a single dose daily for seven days after last risk, and then stop

The reason extra doses are needed is that some HIV is likely to remain in body tissues for a number of days after HIV exposure. By continuing to take PrEP for a few more days, PrEP can continue to work to prevent HIV from entering cells and replicating. If PrEP is stopped immediately, it's possible that an HIV infection could take hold. 

Pharmacokinetic studies show that, after a last PrEP dose has been taken, drug levels drop rapidly in cisgender women's vaginal tissue. In contrast, drug levels are maintained for longer in rectal tissues. This is why the recommendations on how long to continue taking PrEP after a sexual exposure are longer for receptive vaginal sex than for receptive anal sex.

Also, PrEP users living with hepatitis B should see question 44.

When restarting oral PrEP, simply follow the same procedures as for starting PrEP. In other words, take a double dose (two pills) between 2 and 24 hours before sex (or another possible exposure to HIV). Doses after this are single doses (one pill).

This is also known as ‘on-demand’ dosing and ‘2-1-1’ PrEP. It involves taking a few doses of PrEP before and after having sex. 

While it’s often contrasted with daily dosing, the information in the previous three questions (29, 30 and 31) applies both to ‘daily’ and ‘on-demand’ dosing. PrEP users can start, stop and re-start PrEP in the same way. 

The main difference is whether PrEP is taken for a short or long period of time. People using event-based dosing may only take enough PrEP to protect themselves during one day, a weekend or a holiday, for example. People following daily dosing usually intend to continue taking PrEP for several weeks, months or years.

Event-based dosing was tested in the French IPERGAY study – this provides evidence for its effectiveness for people having receptive or insertive anal sex. Study participants were advised to take a double dose of PrEP (two pills) from 2-24 hours before sex, and then additional pills 24 hours and 48 hours after the double dose. In the event of sex on several days in a row, one pill is taken each day until 48 hours after the last sexual intercourse. 

While IPERGAY tested this schedule with TDF/FTC, the recent UK guidelines support TAF/FTC being used in the same way. The UK guidelines also support a modified form of event-based dosing by cisgender women and others, which is not recommended in most international guidelines. (Most other guidelines state that event-based dosing should only be used by gay or bisexual men who need protection during anal sex – because they were the primary group in IPERGAY, the only randomised study to test this regimen. See question 11 for more on why guidelines differ).

In the recent UK guidelines, people whose HIV risk is through receptive frontal/vaginal or neovaginal sex, or injecting drug use, are advised to  take PrEP for an additional seven days after their last possible exposure to HIV. (This is in line with the information on stopping PrEP in question 30). In practice, it means that using PrEP to cover short periods of possible exposure to HIV – such as a weekend – is less practical, but not impossible, for cisgender women and members of some other groups.

Finally, while current UK guidelines support the use of event-based dosing by all people having anal sex, there are some scientists who have a different position for people using feminising hormones who were assigned male at birth (including transgender women) - see question 51.

Oral PrEP users are advised to take the pill at around the same time each day (give or take a couple of hours). It may be easier to get into the habit of taking PrEP if it is combined with a daily routine, such as around meal times, brushing teeth, or going to bed. Where pills are kept may be important – for some people, it helps to have them in a place where they will be easily seen at the right time, while for others the pills must be kept out of the sight of other people. It may also help to carry a few spare pills in a backpack or handbag or on a keyring. A pill box can make it easy to see whether a dose has been taken or missed. Alarms can be set on a phone, watch or a PrEP adherence app.

Specifically for people following event-based dosing, a set of six easy steps has been developed to help people ensure they know what pills to take when. For this approach, making some kind of record of risk encounters and doses taken is recommended. This can be done using an app, diary or calendar. During party weekends, doses can even be noted on a forearm using permanent markers or in a note-taking phone app. If someone is in doubt about when they had their last encounter, there is no harm in taking follow-up doses for another few days.

Medicines should generally be kept somewhere cool and dry, out of the reach of children and animals. While it’s fine to put a month’s worth of tablets in a pill box, PrEP stored over a longer period should be kept in its original container (which may contain a desiccant to absorb moisture). Oral PrEP tablets should not be exposed to temperatures above 30°C.

The pharmaceutical company will have tested the drug’s stability under certain storage conditions (such as temperature) and for a specified amount of time after manufacture. It’s therefore known that the medication will remain safe, effective and potent until the specified date. What happens in other storage conditions and after that date is simply unknown – the drug probably hasn’t been tested over longer periods of time.

There is no reason to think that PrEP instantly becomes ineffective after the expiration date, but it would be preferable to get new supplies which are ‘in date’. However, if that is difficult or delayed and the person is going to be exposed to a possible HIV risk, it’s probably better to take some PrEP (with the risk that is sub-optimal) than to take no PrEP. If someone has access to both some ‘out of date’ PrEP and limited supplies of ‘in date’ PrEP, one option would be to alternate doses from each supply – even if the older medication is suboptimal, it may work alongside the more effective medication.

Multiple studies have shown that pill sharing is common among people who take PrEP. Some people may share it with friends/partners as PrEP, while others might share it to use as PEP when they have an emergency. However, it’s important to know that, in the UK, it is illegal to share prescription medications, including PrEP. 

There are risks associated with sharing medication. The friend/partner who the PrEP is being used by may be taking the medication without medical supervision – a healthcare provider won’t have the opportunity to conduct the necessary tests, verify that they don’t have HIV or hepatitis B, check for drug interactions, and so on.

It might mean the medication doesn’t work for them properly, in particular when someone uses PrEP as PEP. There are three drugs in PEP – usually the same two that are taken for PrEP, plus a third one. The third one would be missing if someone used PrEP as PEP. (See question 20 for more information about PEP).

Sharing PrEP might also mean the person who was prescribed PrEP won’t have enough medication for themselves. For someone prescribed daily PrEP, research suggests that four doses a week may be enough to provide protection. (See question 18).

For ongoing PrEP, cabotegravir injections are every eight weeks. 

However, the schedule is a little different at the beginning. There are two different ways people can start:

• Start with one injection, followed by a second injection four weeks later. After the second injection, cabotegravir injections are every eight weeks.

• Alternatively, take cabotegravir as a daily tablet for four weeks, and then follow the injection schedule above. This option is mostly offered to people concerned about tolerability and side-effects – if problems occur, oral cabotegravir can be stopped immediately and any side effects will go away quickly.

One week after the first injection, cabotegravir will provide complete protection against HIV. After each injection, protection lasts for eight weeks – it’s important not to delay the follow-up injection. Nonetheless, there is a 14-day dosing window – it’s OK to have the injection up to seven days before or up to seven days after the scheduled date.

For ongoing PrEP, lenacapavir injections are every six months.

However, lenacapavir tablets also need to be taken at the time of the first injection. Two tablets should be taken on the day of the injection, followed by two more tablets the next day. As long as these tablets are taken, protective levels are reached within two days; if they are not, it may take several weeks.

As with cabotegravir, there is a 14-day dosing window – it’s OK to have the injection up to seven days before or up to seven days after the scheduled date.

One of the drugs used in the mostly widely used PrEP tablet, tenofovir disoproxil (TDF), is processed by the kidneys and can put additional strain on the kidneys in people who already have kidney problems. 

None of the other types of PrEP has the same impact on the kidneys, so are safer alternatives for people with kidney problems. In particular, the other type of PrEP tablet (TAF/FTC) is recommended in the UK guidelines for people who have moderate kidney disease.

Nonetheless, it’s rare for PrEP to cause kidney problems. In a study comparing the two oral PrEP tablets, six of 2693 people (0.2%) taking TDF/FTC stopped PrEP because of kidney concerns. Two of the 2694 people (0.07%) taking TAF/FTC stopped PrEP for the same reason.

A blood test to check kidney function is required around the time of starting PrEP and at least once a year while on oral PrEP. This measures levels of a waste product called creatinine – a build-up of creatinine indicates a loss of kidney function. Results are reported as an estimated glomerular filtration rate (eGFR):

• eGFR above 90: normal kidney function, PrEP is safe to use.

• eGFR between 60 and 89: mild kidney disease, PrEP containing TDF can be used, but event-based PrEP (see question 32) should be considered (to reduce drug exposure) and kidney function should be checked more often.

• eGFR between 30 and 59: moderate kidney disease, PrEP containing TAF/FTC should be offered.

If a test shows a rise in eGFR, this could indicate a problem, but the test needs to be repeated. More often than not, results return to a normal level on the second test, and it is safe to continue with PrEP. When people stop PrEP containing TDF, kidney function usually returns to its previous level, suggesting that PrEP does not cause any long-term harm. 

PrEP users should tell their clinic if they use protein or creatine powders, as they can impact the results of this blood test. (See question 52).

People at greater risk of kidney problems are those over the age of 40, people who have high blood pressure or diabetes, and people taking other drugs which are processed by the kidneys.

A slight decrease in the hardness of bones has been seen in the first six months of taking oral PrEP that contains TDF. This reduction in bone density is small (0.5-1.5%) and will not make a difference to people with normal bone density prior to using PrEP. There have not been any reports of bone fractures related to PrEP use.

The loss of bone mineral density does not get worse with ongoing PrEP use. Importantly, bone mineral density returns to normal after stopping PrEP that contains TDF.

The other types of PrEP don’t have the same impact on the bones, so are safer alternatives for people with bone problems. This includes the other type of PrEP tablet (TAF/FTC).

Adolescence is a critical period for bone growth and development. Recent UK guidelines therefore recommend that for people under the age of 18, TAF/FTC should be offered instead of TDF/FTC. Young people who have started to take TAF/FTC can continue on it until the age of 20. 

In the UK guidelines, routine measurement of bone mineral density in PrEP users is not recommended (the scan involves exposure to radiation and not many PrEP users have bone problems anyway). However, doctors prescribing PrEP should make an assessment of whether a PrEP user has other risk factors for bone problems (such as smoking, menopause, long-term use of some steroids, or having a low body weight). 

• If they are under the age of 50 and don’t have risk factors, this assessment does not need to be repeated

• If they are at ‘intermediate’ risk of a bone fracture, this assessment should be repeated every year. Event-based PrEP (see question 32) could be considered (to reduce drug exposure)

• If they are at higher risk, their bone mineral density should be measured with a DEXA scan. Alternatives to TDF/FTC, such as TAF/FTC, should be considered

Vitamin D and calcium supplements may be helpful for PrEP users with risk factors for reduced bone mineral density, particularly people under the age of 25.

HIV medications can have an impact on the weight of people taking them as HIV treatment, and this is also possible when they are taken as PrEP.

In terms of oral PrEP, the most widely used tablet contains tenofovir disoproxil (TDF), which is thought to suppress weight gain. The other tablet contains tenofovir alafenamide (TAF), which promotes weight gain. After almost two years in the randomised controlled trial which compared the two tablets when taken by cisgender GBMSM and transgender women, median weight gain was 1.7kg in those receiving TAF/FTC compared to 0.5kg in those receiving TDF/FTC. 

The key studies for cabotegravir compared it with TDF/FTC. In the study enrolling cisgender GBMSM and transgender women, mean weight gain was 1.2kg per year in those taking cabotegravir and 0.4kg per year in those taking TDF/FTC. In the study enrolling cisgender women in Africa, mean weight gain was 2.4kg per year on cabotegravir and 2.1kg per year on TDF/FTC. In both cabotegravir studies, the differences were greatest in the first few months receiving PrEP and became less important as time went on.

Weight gain has not been assessed in relation to lenacapavir.

Pain, tenderness and swelling at the injection site are commonly reported after cabotegravir injections, but people tend to get used to them. In the large study recruiting gay and bisexual men and transgender women, 81% ever reported an injection site reaction, but reports were most common after the first or second injection. In almost all cases, the reaction was graded as mild or moderate (rather than severe) and resolved within a few days. Only 2.4% of participants stopped having the injections for this reason. In the cabotegravir study recruiting cisgender African women there was a similar pattern, although fewer women reported these problems.

Results were very similar in the two studies of injectable lenacapvir. The main difference is that after lenacapavir injection, the drug accumulates in a small ‘nodule’ in the fat layer of the abdomen. This slowly releases the drug over a period of weeks and months, and is harmless and not painful. However a lump of between 2 to 4cm size may be felt under the skin and could be visible (especially if you are lean).

Less than one-in-ten people report side-effects such as feeling sick, flatulence, abdominal pain, dizziness and headache in the first month taking oral PrEP. These side effects are usually mild and short-lived. Typically, they start in the first few days or weeks of PrEP use and last a few days, and almost always finish within a month. 

For people using injectable cabotegravir, common side-effects include diarrhoea, headache, raised liver enzymes and feeling hot or feverish. Lenacapavir and the vaginal ring have both been reported to have limited side-effects.

Over-the-counter and prescription medications – such as painkillers and anti-sickness tablets – can help with some of these side-effects.

UK guidelines support the use of PrEP containing TDF/FTC during pregnancy, breastfeeding and chest feeding. They state that the benefits of preventing HIV acquisition in pregnancy greatly outweigh any potential negative consequences for the parent or infant.

These drugs have been widely used by people living with HIV for many years, including during pregnancy. Studies have found minimal differences in the weight, growth, bone health or neurological development of babies born to those taking PrEP, or in the rate of adverse pregnancy outcomes such as stillbirth, premature birth or neonatal death.

However, it is worth noting that many studies of PrEP have excluded pregnant and breastfeeding women. Most of the guidelines that advise on PrEP use during pregnancy and breastfeeding are relatively new. There are some ongoing studies and planned studies which will provide further data about safety.

Guidelines do not yet include recommendations on other types of PrEP. The first cabotegravir, lenacapavir and vaginal ring studies raised no safety concerns when used in pregnancy. The vaginal ring also appears safe during breastfeeding and chestfeeding, but there is no data yet on cabotegravir or lenacapavir during breastfeeding and chestfeeding. There is no data yet on TAF/FTC when taken as PrEP during pregnancy, but it’s worth noting that BHIVA guidelines for pregnancy among people with HIV advise against using TAF during the first trimester.

Tenofovir disoproxil and tenofovir alafenamide, which are included in oral PrEP tablets, are also used to treat hepatitis B. This means that the PrEP will also help keep hepatitis B under control, which is an advantage oral PrEP has compared to other types of PrEP (which do not have any activity against hepatitis B).

However, people living with hepatitis B must take oral PrEP every day – they should not start and stop PrEP just for the times they need HIV protection. Also, before taking a break from PrEP, they should get advice on how to safely stop taking it. Stopping tenofovir suddenly could lead to a flare up of hepatitis B – this means that the virus is reactivated, which results in raised liver enzyme blood tests.

People taking all types of PrEP are recommended to have regular tests for HIV and sexually transmitted infections. Recommendations for hepatitis C and pregnancy testing depend on each person’s situation. For more details, see chapter 7 of the UK guidelines.

People taking oral PrEP should have regular tests for kidney function, but these aren’t needed by people taking injectable PrEP or using the vaginal ring.

HIV testing is recommended every three to six months for PrEP users, depending on the amount and type of sex being had. Some people may question why this is necessary.

It’s worth remembering that some oral PrEP users find it difficult to take the medication consistently. Even for those who do, no HIV prevention method is 100% effective.

At the same time, early detection of HIV infection is extremely important. While the drugs contained in PrEP are also used to treat HIV, they need to be combined with additional antiretroviral drugs in order to form a strong and effective HIV treatment combination. In a situation in which someone has acquired HIV (perhaps due to missed PrEP doses), and then starts or continues to take PrEP, this would in effect be a sub-optimal HIV treatment regimen. It would not be strong enough to keep HIV under control and there would be a high risk of drug resistance developing. (See question 56).

Early detection of HIV infection allows people who have seroconverted to start HIV treatment without delay, which will also help prevent inflammation and damage to the immune system, which has long-term benefits for health.

Regular HIV testing does not indicate that PrEP is not effective. Rather, it provides a ‘fail safe’ mechanism, to safely manage rare events.

Occasionally, some PrEP users may acquire HIV, usually because of missed doses. This may mean that they may be taking PrEP during the early stages of infection, before a diagnosis is made. In this case it is possible that the window period (the period when HIV testing cannot detect HIV infection) may be longer than usual. 

Tests might not detect signs of infection in the first few weeks or months after infection. This can occur with all kinds of tests, including antibody/antigen tests and viral load (HIV RNA) tests. The problem is most common with tests which give an immediate result (point-of-care tests), rather than ones which involve sending a sample for analysis in a laboratory. 

The explanation for this appears to be that having some antiretroviral drugs in the body during the first stages of infection (acute HIV infection) slows down replication of HIV. This in turn decreases or delays the development of an immune response to HIV, including the production of antibodies. 

The problem is particularly frequent in people using injectable cabotegravir, perhaps because the antiretroviral remains active in the blood for longer.

PrEP drugs do not interact with most other medicines. This applies to TDF/FTC, TAF/FTC, cabotegravir and the vaginal ring. Lenacapavir does have a larger number of potential drug interactions.

However, tenofovir disoproxil (TDF, one of the drugs in the mostly widely used PrEP tablet) may interact with other medicines which are also associated with kidney problems. These include some non-steroidal anti-inflammatory drugs (NSAIDs), such as naproxen and diclofenac; aminoglycosides, used to treat certain bacterial infections; and acyclovir and valaciclovir, used to treat herpes. 

When PrEP users are prescribed other medicines, they are strongly advised to tell the doctor or pharmacist about taking PrEP and ask them to check for drug interactions. 

The University of Liverpool provides an online tool to check for interactions between anti-HIV drugs (including PrEP) and other medications. You enter the names of your PrEP drugs in the left column, and the other medications you are taking in the next column. The results are provided with a traffic-light system: if the result is red or amber, it’s worth checking with your doctor or pharmacist. If it’s green, there shouldn’t be any problem. Visit www.hiv-druginteractions.org/checker or download the Liverpool HIV iChart app for iPhone or Android.

No. There are no expected significant drug interactions between PrEP and hormonal contraceptives. 

However, vaginal rings for PrEP and vaginal rings for contraception should not be used at the same time.

No. There are no expected significant drug interactions between PrEP and hormone replacement therapy (HRT) taken during the menopause.

Recent UK guidelines state that people considering PrEP should be given reassurance that there are no expected drug–drug interactions between PrEP and gender affirming hormone therapy. Specific details can be checked on the Liverpool interactions website.

A number of studies have examined drug levels of both oral PrEP drugs and gender affirming hormones. The available evidence indicates that PrEP does not significantly affect the blood levels of the hormones studied (including estradiol, cytoproterone, spironolactone, progesterone, testosterone and finasteride). 

However, in people assigned male at birth, the use of estradiol and other feminising hormones may lead to slightly lower levels of the PrEP drug tenofovir. While this does not affect the efficacy of daily PrEP, this has led some experts to argue against event-driven PrEP (‘2-1-1 dosing’) for people assigned male at birth using feminising hormones (including transgender women). This is, for example, the position of the World Health Organization. However, UK guidelines do support event-driven PrEP (‘2-1-1 dosing’) for all people whose risk is through receptive anal sex, regardless of their use of hormones or gender assigned at birth. They are advised to take a single dose daily for two days after the last risk, and then stop. If someone assigned male at birth taking feminising hormones wants extra reassurance given the lack of scientific consensus on this point, they could decide to take a single dose daily for seven days after their last risk, and then stop - this is in line with World Health Organization guidance.

We have less evidence for the interaction with masculinising hormones but what we do have suggests that oral PrEP levels in people using gender-affirming hormones do not differ significantly from levels in cisgender men. While levels do differ from those in cisgender women, there is no evidence so far that this is likely to have an impact on PrEP efficacy. 

There is a potential interaction between cabotegravir and testosterone supplements, leading to cabotegravir being eliminated from the body more rapidly and therefore losing its efficacy. It’s unclear how frequent this occurs: doctors are advised to consider monitoring cabotegravir drug levels in people using testosterone supplements.

Creatine is a supplement, often taken by bodybuilders who want to increase the amount of muscle repair that occurs after resistance training, and to increase their performance in the gym. Creatine supplements do not interact with PrEP and do not cause long-term kidney damage. 

But creatine supplements and also protein shakes can affect the results of kidney function tests – taking them can make it look as though the kidneys are not functioning normally. If a doctor does not know that a PrEP user is taking creatine supplements or protein shakes, they may say that PrEP containing TDF/FTC should not be prescribed. 

After having the supplement or shake, there may be a rise in creatinine levels in blood. This is temporary (mostly seen on the same day) and is not thought to represent a true decline in kidney function (unlike raised creatine levels linked to TDF/FTC). Creatinine levels are measured regularly in people taking oral PrEP and converted to eGFR. (See question 38).

So, it’s important that the person prescribing PrEP knows about any supplements that are being taken.

In relation to injectable cabotegravir, the University of Liverpool interactions site does list potential interactions with some anabolic steroids (including analogs of testosterone) and enobosarm (ostarine), a non-steroid which stimulates muscle growth.

No. There are no expected drug interactions between PrEP (TDF/FTC, TAF/FTC or cabotegravir) and erectile dysfunction drugs. 

However, there may be an interaction with lenacapavir, with the result that the amount of erectile dysfunction medication in your system may be increased. This can increase the side-effects that you experience from the erectile dysfunction medicine and can sometimes be dangerous. 

In order to manage the interaction with lenacapavir, a lower dose of the erectile dysfunction drug should be taken - if you are receiving the drugs from a doctor or pharmacist, they will be able to manage and monitor the situation. If you’re buying erectile dysfunction medication without speaking to a doctor or pharmacist, it will be more difficult to know how much you can safely take.  There is more information on the Liverpool interactions website.

No. There are no expected drug interactions between PrEP (TDF/FTC, TAF/FTC, cabotegravir, vaginal ring) and alcohol, amphetamine, cannabis, cocaine, ecstasy (MDMA), fentanyl, GHB, heroin, LSD, mephedrone, methamphetamine, nitazines, PCP and psilocybin. 

In relation to lenacapavir, there can be dangerous interactions with nitazenes (a type of synthetic opiod) and with fentanyl, in both cases raising the risk of overdose from the illicit drug. There is also the potential for interactions with GHB and PCP, again increasing the amount of the recreational drug in your system. There is more information on the Liverpool interactions website.

People who have taken PrEP (or PEP) in the past three months are not eligible to donate blood in the UK. The reasoning behind this is that when antiretroviral drugs are present, HIV screening tests are occasionally unable to detect markers of infection (including HIV RNA, antibodies and antigen) in the first few weeks or months after infection (see question 47).

While PrEP is highly effective, occasionally a PrEP user might acquire HIV, usually because of missed doses. Donated blood in the UK is screened for HIV and other blood-borne viruses, but all screening tests have what’s called a ‘window period’. This is a period of time after someone acquires an infection where the test won’t show as positive yet. In normal circumstances, screening tests can reliably identify hepatitis infections that were acquired more than three months ago and HIV infections that were acquired more than 45 days ago. It appears that the window period for HIV tests may occasionally be longer in PrEP and PEP users, although this is currently uncertain (because of a lack of clear evidence).

Scientific understanding of the accuracy of HIV testing in PrEP users is evolving. When we have clearer evidence, policy might change.

Of note, potential blood donors are also asked some questions about their sexual behaviour in the last three months (a time period which aligns with the length of different tests’ window periods). People of any gender who have had anal sex with a new partner or multiple partners in the past three months cannot donate blood, and this would also exclude many PrEP users from donating.

Some PrEP users worry that they may develop HIV drug resistance while taking PrEP. However, it’s important to remember that the only way this could happen is if they unwittingly take PrEP while they already have HIV. This could be because they didn't take an HIV test before they started PrEP. Alternatively, they may have taken a test but acquired HIV so recently (within the last two to three weeks) that the test didn't detect it. Regular testing while on PrEP reduces the risk of any resistance developing.

If someone continues taking PrEP or starts taking PrEP again after acquiring HIV, this could drive HIV to develop resistance to the drugs they are taking as PrEP. The anti-HIV drugs in PrEP are not strong enough to suppress an established HIV infection (an additional anti-HIV drug is usually needed for HIV treatment). In these conditions, HIV will replicate and could become resistant to those anti-HIV drugs. 

This has been seen in people who acquired HIV but continued to take oral PrEP – in these cases, resistance generally developed to emtricitabine (FTC) rather than to tenofovir. It has also been seen, probably at a greater frequency, in people who acquired HIV while taking injectable cabotegravir. Resistance is anticipated to be less of a concern with the vaginal ring or with injectable lenacapavir.

Resistance that develops in this way can limit the person’s options for treating HIV, but it doesn’t make their HIV untreatable. There are several other anti-HIV drugs, especially those from other drug classes, that will continue to be effective.

But if a PrEP user is taking PrEP as directed, was tested for HIV before they started and continues to be tested regularly, then they should remain HIV negative. And a person who does not have HIV cannot, by definition, have drug-resistant HIV.

There is another way in which resistance can affect PrEP. In the small number of documented cases of people who have acquired HIV when taking PrEP despite having adequate drug levels in their blood, most acquired a form of HIV that had resistance to one of the drugs they were taking as PrEP. (See question 13). The person they acquired HIV from must have had both a detectable viral load and a resistant strain of the virus that made PrEP ineffective. Cases like this are rare, perhaps in part because these circumstances are rare.

PrEP has only been proven to be effective in preventing HIV infection. While some research suggests that PrEP helps prevent new hepatitis B infections, there aren’t many studies on this. 

In contrast, when used correctly and consistently, condoms protect against numerous other infections. DoxyPEP protects against chlamydia and syphilis, and to a lesser extent gonorrhoea. 

There are also five vaccinations against infections which can be passed on during sex. PrEP users should seriously consider getting these vaccinations and seek advice from sexual health clinics on eligibility. The hepatitis B vaccine should be available to most PrEP users, whereas the hepatitis A vaccine is recommended specifically for GBMSM. Vaccination against human papilloma virus (HPV, the cause of warts, anal cancer and cervical cancer) is now offered to 12-13 year olds, but is also available up to 45 years to GBMSM, transgender people, sex workers and others with a comparable risk profile. The mpox vaccine is available to GBMSM with risk factors for mpox, such as recent STIs, multiple partners or use of sex on premises venues. The menB (meningococcal B) vaccine may also provide some protection against gonorrhoea. The Joint Committee on Vaccination and Immunisation (JCVI), an expert committee which advises the UK government on vaccination and immunisation matters, has recommended it for GBMSM and others at elevated risk, but, at the time of writing, it is still not available on the NHS.

In addition, PrEP does not protect against pregnancy. Some PrEP users may need advice on contraception, including reassurance that PrEP does not interfere with any contraceptive method (see question 49).

People who use PrEP, especially gay and bisexual men, tend to have higher rates of gonorrhoea, chlamydia, syphilis and other sexually transmitted infections (STIs) than other people. This indicates that PrEP is being used by people who are likely to benefit from it. They are people who were already having condomless sex and were vulnerable to STIs before they began to take PrEP. But PrEP could have an impact on rates of STIs in other ways. 

Because they are protected by PrEP, people might use condoms less than before, or to have more sexual partners. This is sometimes called 'risk compensation'. 

PrEP also facilitates engagement with sexual health care. Regular screening for STIs is recommended for PrEP users, resulting in infections being diagnosed promptly. In the short term, reported rates of STIs in PrEP users will be high, in part because more testing will result in more diagnoses.

While several studies have reported increased number of STIs among PrEP users, some studies which have tracked this for longer periods have shown that the number of STIs increased before people started PrEP. This would suggest that rather than PrEP having a disinhibitory effect on risk behaviour, people sought PrEP because they knew that their risk behaviour was already changing. Moreover, most STIs occur in a minority of PrEP users. For example, one Dutch study found that 5% of PrEP users had 64% of the STIs in the cohort.

The reason many people want to use PrEP is because they want to avoid HIV acquisition but find it difficult to consistently use condoms. 

In supporting PrEP users, it's important to check that they are aware of the benefits to using condoms in combination with PrEP, in particular in preventing other sexually transmitted infections. It's also worth checking that the difficulties they have with condoms can't be remedied with information and education. This could be the case if someone has problems with fit or breakages, for example. 

Nonetheless, it is to be expected that many PrEP users will not always use condoms. It would be illogical to deny PrEP to people who feel unable to use condoms all the time – they are precisely the people who need it. 

PrEP users tend to be highly motivated to avoid infection with HIV. Some PrEP users may be more prepared to live with the possibility of acquiring other STIs, most of which are easier to treat and cure, as well as being less stigmatised. PrEP users may manage their STI risks by taking doxyPEP, getting available vaccinations (see question 57) and having frequent check-ups so that any STIs can be promptly diagnosed and treated. 

Moreover an individual may consider, for example, that managing erectile dysfunction or building intimacy with partners are higher priorities for their sexual health than avoiding all possible infections. Support for people in relation to PrEP and condom use needs to take account of each individual's sexual health needs and personal priorities.