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About PrEP
What is PrEP?
Medicine you take before sex so HIV can’t take hold if you are exposed to it. It comes as a pill, and in some countries as an injection every two or six months.
Is PrEP only for gay men?
No. PrEP is for anyone who could be exposed to HIV, whatever their gender or sexuality. UK guidance names Black African women and men, and people new to the country, among the people who should be offered it.
Do I need a reason to ask for it?
No. UK guidance says PrEP should be given to anyone who asks for it. You don’t have to explain your sex life to get it.
How well does it work?
Taken as prescribed, PrEP lowers the risk of getting HIV from sex by about 99%. Almost every case of HIV in people using PrEP is linked to not having enough medicine in the body at the time.
When does it start protecting me?
Start with two pills 2 to 24 hours before sex, then carry on with one pill a day or the plan your clinic gives you. That double first dose is recommended for everyone, for all types of sex.
Does PrEP protect me from other STIs?
No. PrEP only protects against HIV. Condoms help protect against other infections and pregnancy, and regular check-ups on PrEP mean other infections are found and treated early.
Taking PrEP
Do I have to take it every day?
Not always. Daily is the simplest plan and works for everyone. Some people take it only around sex instead:
2:1:1 for anal sex and any insertive sex: two pills before sex, then one a day for two days after the last sex. 2:7 for receptive vaginal or frontal sex and for injecting drugs: two pills before, then one a day for seven days after the last sex. Your clinic can help you choose.
What if I miss a pill?
Take it when you remember, then carry on as normal. You don’t need to take two the next day. If you have missed several and have had sex without a condom, contact your clinic and ask about PEP within 72 hours.
What are the side effects?
Most people have none. Fewer than 1 in 10 notice a mild upset stomach in the first few weeks, which usually passes.
Is it safe to take for years?
Yes, for most people. PrEP can cause small changes in kidney function and bone density, which is why your clinic checks your kidneys. These changes usually reverse if PrEP is stopped.
Can I drink alcohol or use drugs on PrEP?
Alcohol and recreational drugs don’t stop PrEP pills working. If they make it harder to remember your pills, a daily routine or an injection may suit you better.
Can I take PrEP with gender-affirming hormones?
Yes. Oral PrEP and gender-affirming hormones can be taken together, and studies have not shown hormones making PrEP pills less effective. Tell your clinic about all the medicines you take.
My partner is living with HIV. Do I need PrEP?
If your partner takes HIV treatment and has an undetectable viral load, they can’t pass HIV on through sex (Undetectable = Untransmittable). Some couples still choose PrEP, for example while treatment is starting. It is your choice.
How do I stop safely?
Keep taking one pill a day for two days after your last anal or insertive sex, or seven days after your last receptive vaginal or frontal sex. Have an HIV test about six weeks later. You can restart at any time.
What about the PrEP injection?
Getting PrEP
Is PrEP free?
In many countries, yes or nearly. It is free in the UK, free for eligible people in Ireland and Spain, and fully reimbursed in France. 27 countries in the region fund it nationally.
Check your countryDoes my immigration status matter?
What happens at the first appointment?
A short, confidential chat about how PrEP fits your life, an HIV test, and tests for hepatitis B and C, other STIs and kidney function. In many clinics you can leave with PrEP the same day while results come back.
How often will I need check-ups?
Usually every three months, or three to six months if your situation is steady. Each visit includes an HIV test so PrEP stays safe for you.
Do I have to tell my GP or family?
No. Who you tell is your choice. UK sexual health clinics won’t tell your GP without your consent. Rules differ in other countries, so ask your clinic.
Can I get PrEP if I don’t speak the local language?
Yes. Many clinics can arrange an interpreter, often free of charge. Our guides are also available in several languages.
Guides in your languageCan I take PrEP if I’m pregnant or breastfeeding?
Yes. Oral PrEP can be continued in pregnancy and is considered very safe while breastfeeding. It is safe alongside all kinds of contraception.
Who to offer
Who should be offered PrEP?
Anyone who could benefit, and anyone who asks. BASHH/BHIVA 2025 drops restrictive eligibility criteria and names Black African women and men, and recent migrants, among the groups to offer it to.
Didn’t most migrants acquire HIV before arriving?
Many didn’t. An estimated 45% of sub-Saharan African migrants living with HIV in nine European countries acquired it after migrating.
How do I bring PrEP up without it feeling awkward?
Make it routine: mention it to everyone at HIV and STI testing, contraception, antenatal and new-patient visits. Frame it as choice and control rather than risk, and avoid asking people to justify wanting it.
Read guide 0013What if my patient is undocumented?
Routes vary. In England, sexual health clinics provide PrEP free regardless of status. In France, AME and PASS services help. In 2024, 16 countries in the region said PrEP was not available to undocumented migrants.
Country routesStarting PrEP
Which tests are needed before starting?
Lab HIV Ag/Ab (or a negative blood-based rapid test if there has been no lab test in six weeks), HBsAg, hepatitis C, a full STI screen, and creatinine with eGFR. Kidney results are not needed before the first prescription.
Monitoring checklistCan PrEP start on the same day?
Yes, and UK guidance encourages it. Start while results are pending, unless there are symptoms suggesting recent HIV. If there was a possible exposure in the last four weeks, start and repeat the HIV test at four weeks.
Same-day guideSomeone has just finished PEP. What next?
If they are likely to be exposed again, move straight from PEP to PrEP without a gap, with an HIV test at the switch and again four weeks later.
Prescribing
Which dosing should I offer?
Daily dosing works for everyone. 2:1:1 suits anal and any insertive sex. 2:7 suits receptive vaginal or frontal sex and injecting drug use. All start with a double dose 2 to 24 hours before sex.
Can women use event-based dosing?
UK 2025 guidance offers 2:7 for receptive vaginal or frontal sex. WHO recommends event-based dosing only for men who have sex with men. Daily dosing remains the simplest option.
What about kidney function?
Tenofovir disoproxil with emtricitabine needs an eGFR of 60 or more. Below that, use tenofovir alafenamide with emtricitabine where available. Check eGFR yearly, or six-monthly from age 40 or with renal risk factors.
What about patients with hepatitis B?
Use daily PrEP, not event-based, with specialist input. Stopping can trigger a hepatitis flare, so monitor HBV DNA and liver tests for 12 months after stopping.
Hepatitis B guideIs PrEP safe in pregnancy and breastfeeding?
Oral PrEP is recommended to continue in pregnancy and is considered very safe in breastfeeding. Cabotegravir is not recommended in pregnancy unless the expected benefit justifies the potential risk.
Pregnancy guideWhat if someone acquires HIV while on PrEP?
It is rare, and usually linked to low adherence or HIV acquired before starting. Test promptly, take a resistance test, and refer for treatment straight away. Regular testing on PrEP keeps this risk low.
Long-acting PrEP
What is needed before long-acting PrEP?
An HIV RNA test as well as Ag/Ab before starting cabotegravir and at each injection. Check for interacting drugs, including rifampicin and some anticonvulsants.
Where is long-acting PrEP available?
Cabotegravir is authorised in the EU and used in some countries, including France and Spain. In England and Wales, NICE recommends it for people who cannot take oral PrEP. Lenacapavir was EU-authorised in August 2025 and is recommended by WHO; national availability varies.
Long-acting guideDidn’t find your question?
We answer common questions here. We can’t give personal medical advice.