PrEP, or pre-exposure prophylaxis, is a medicine taken by people who are HIV-negative to greatly reduce their chance of getting HIV. Taken as prescribed, PrEP lowers the risk of getting HIV from sex by about 99%, according to the CDC. It is a safe, evidence-based prevention tool.
How does PrEP work?
PrEP uses antiretroviral medicines, the same class of drugs used to treat HIV. When present in your body before exposure, these medicines block HIV from establishing itself and making copies of itself. If you are not on PrEP and are exposed, the virus can take hold quickly; PrEP works by stopping that process before it starts.
PrEP only works if there is enough medicine in your system at the time of exposure. That is why taking it exactly as prescribed, and keeping regular appointments, is essential.
Who is PrEP for?
PrEP is for adults and adolescents who are HIV-negative and may be exposed to HIV. The WHO and CDC describe it as part of a broader prevention approach. A provider may discuss PrEP with you if you:
- Have a sexual partner living with HIV
- Have multiple sexual partners or a partner whose status you do not know
- Do not consistently use condoms
- Share equipment to inject drugs
- Have recently had certain STIs or used PEP more than once
PrEP is for people of all genders and orientations. The NHS specifically notes it is suitable for men who have sex with men, transgender and non-binary people, sex workers, and others at higher risk. Choosing PrEP says nothing about your character or identity; it is simply a prevention decision made with a clinician.
What are the PrEP options?
There is no longer a single way to take PrEP. Current options, as described by HIV.gov and the WHO, include:
- Daily oral pills. Tablets combining tenofovir and emtricitabine, taken once a day.
- Long-acting injections. An injectable given every two months, and a newer twice-yearly option, both administered by a healthcare provider.
- On-demand (event-based) dosing. For some people, oral PrEP can be taken around the time of sex rather than daily. The NHS notes this approach has specific timing rules and is not suitable for everyone.
Which option fits depends on your health, preferences, and your provider's guidance.
Is PrEP safe?
PrEP has a strong safety record. HIV.gov reports no significant health effects in HIV-negative people who used PrEP for up to five years. Some people have mild, temporary side effects when starting, such as nausea, headache, diarrhoea, or tiredness, which usually settle within a few weeks.
Because PrEP affects the kidneys in a small number of people, providers check certain lab values before and during use. PrEP has no known harmful interactions with hormone therapy or most birth control, though you should always tell your provider about every medicine you take, including gender-affirming care.
Getting started and staying on PrEP
Starting PrEP involves a few steps with a provider:
- An HIV test to confirm you are negative, since PrEP alone is not enough to treat HIV.
- Baseline checks, which may include kidney function and STI screening.
- Follow-up visits, usually every few months, for repeat HIV and STI testing.
Cost should not be a barrier for many people. In the US, the CDC notes most insurance plans and Medicaid cover PrEP, and assistance programs exist for those who are uninsured. In the UK, PrEP is available through NHS sexual health clinics.
If you are looking for a clinician who understands your needs, our guide to finding LGBTQ+ affirming healthcare can help. You can also explore the wider LGBTQ+ sexual health hub, including what PEP is for emergencies and how undetectable equals untransmittable fits into prevention.
The bottom line
PrEP is a safe, highly effective medicine that prevents HIV when taken as prescribed, available as a daily pill or a long-acting injection. It is for anyone at higher risk of HIV, of any gender or orientation, and it works best alongside condoms and regular testing. The next step is a conversation with a knowledgeable healthcare provider, who can confirm whether PrEP is right for you and which option fits your life.
