PrEP (pre-exposure-prophylaxis) is a pill that protects you from HIV. It's taken by HIV-negative people before and after sex.
Taking PrEP before and after sex means there’s enough drug inside you to block HIV if it gets into your body – before it has the chance to take hold. It’s highly effective at stopping HIV from being transmitted when taken correctly.
PrEP offers protection during frontal and anal sex. It’s safe to use for trans masculine and non-binary people and is effective regardless of any gender-affirming surgeries that you’ve had.
Is PrEP right for you?
PrEP might be right for you if you’re HIV negative and have sex in a variety of situations where condoms are not easily or always used. It gives you empowerment, particularly if you are a receptive partner, or bottom, by taking control over protecting yourself from HIV transmission.
How to take PrEP
The way you take PrEP depends on the type of sex you have, but generally daily dosing is recommended for anyone taking gender-affirming hormones.
For anyone having frontal sex, daily PrEP is the only option. This is to make sure PrEP levels are high enough in these tissues to provide protection against HIV. Daily PrEP needs to be taken for seven days until it becomes fully effective.
Another reason why daily PrEP is recommended is that for anyone taking testosterone this might reduce your natural lubrication and thin the tissue inside the front hole. Clinical studies suggest that daily PrEP will reach effective levels in trans people, of any gender, who are taking cross sex hormones. Daily PrEP is therefore recommended as being the best option for anyone for anyone assigned female at birth.
Another way of taking PrEP is on-demand or 'event-based' dosing, where PrEP is taken only around the time you have sex: two tablets two to 24 hours before sex, one tablet 24 hours after sex and a further tablet 48 hours after sex.
You should only take PrEP this way if your only risk is from having anal sex and you’re not on gender-affirming hormones. If you're not sure which is the best way for you to take it, daily dosing will offer the best protection.
PrEP is very safe and serious side effects are very rare. A few people experience nausea, headaches or tiredness which tend to only last a few days or weeks.
The drugs most commonly used for PrEP are emtricitabine and tenofovir (which are combined in a single tablet).
Interaction with hormones
The British HIV Association (BHIVA) guidelines note that there are no known interactions between PrEP and gender-affirming hormones. PrEP will not stop any hormones you are taking from working.
We recommend daily PrEP for anyone taking gender-affirming hormones as there is insufficient data to support other dosing options.
Gender-affirming hormones might reduce natural lubrication and thin the tissue inside the front hole, so daily PrEP will ensure protective levels.
PrEP does not cause fat redistribution in the body or face.
You can take hormone replacement therapy for menopause while on PrEP.
Before taking PrEP
Before taking PrEP, have a full sexual health screen at a local clinic, including an HIV test and a test for kidney function.
While taking PrEP, test for HIV and all other STIs every three months.
Where to obtain PrEP
You can get PrEP for free on the NHS from a sexual health clinic.
PrEP can also be bought from a reliable source.
PrEP and contraception, conception and breast/chest feeding
When you take PrEP, you can safely:
- Get pregnant. PrEP prevents HIV, not pregnancies. Continue to use contraception to avoid pregnancy.
- Take hormonal birth control. It's safe and both will work if taken correctly.
- Conceive and carry a baby. It's safe for you and your baby.
If you want to stop taking PrEP
If you want to stop taking PrEP for any reason and are taking it daily, you should continue taking it for seven days after the last time you have sex without a condom.
Get tested for HIV before you start taking it again. If you have acquired HIV and begin taking PrEP, you may develop resistance to the drugs used for PrEP which could affect future treatment options if you are HIV positive.
If you are living with hepatitis B, be aware that PrEP can suppress the virus – you should always use daily dosing of PrEP and should not stop taking PrEP until you've got advice from your doctor.
PEP (post-exposure prophylaxis for HIV) is a treatment that can stop an HIV infection after the virus has entered a person’s body (for example, if you’ve had sex and the condom fails). To work, PEP must be taken within 72 hours (three days), and ideally should be taken within 24 hours.
If you think you've put yourself at risk of HIV it might be worth accessing post-exposure prophylaxis (PEP).
You can access PEP from a sexual health clinics or A&E. Tell your doctor if you're taking any hormones and any other drugs or medications.