HIV Post-exposure Prophylaxis (PEP)
If you think you have been exposed to HIV, it is important to act quickly. HIV Post-Exposure Prophylaxis (PEP) is an emergency treatment that can help stop HIV infection after a possible exposure. PEP must be started as soon as possible and within 72 hours (3 days) of exposure to be effective.
What is PEP?
Post-Exposure Prophylaxis (PEP) is a course of HIV medicines that can reduce the chance of getting HIV after a possible exposure. It is used after a potential exposure to HIV, such as after condomless sex, sexual assault, or another situation where HIV transmission may have occurred. PEP is not a cure for HIV and does not guarantee that HIV infection will be prevented, but it can be very effective when taken correctly and started quickly.
How does PEP work?
PEP works by reducing the chance that HIV establishes infection after a possible exposure. The treatment uses anti-HIV medicines that interfere with the virus's ability to replicate and spread. To give PEP the best chance of working, it should be started as soon as possible after exposure, ideally within 24 hours and no later than 72 hours.
Do I need PEP?
You may be offered PEP if you have recently been exposed to HIV and there is a significant risk of transmission. This could include:
- Condomless sex with someone living with HIV who is not on effective treatment
- Condom failure during sex
- Sexual assault
- Sharing injecting equipment
- Missing doses of PrEP before a potential HIV exposure
A healthcare professional will assess the risk and advise whether PEP is recommended. PEP is not needed after contact with someone living with HIV who has an undetectable viral load, as HIV cannot be passed on sexually in this situation (Undetectable = Untransmittable, or U=U).
How long do you need to take PEP for?
PEP is taken every day for 28 days. It is important to take all doses as prescribed and complete the full course, even if you feel well. Stopping treatment early may reduce its effectiveness. You will usually be offered follow-up HIV testing after completing PEP to confirm that HIV infection has not occurred.
Will I have to pay?
No. PEP is available free of charge through NHS sexual health services and emergency departments when it is clinically recommended.
Can I have sex when on PEP?
Yes, but it is recommended that you use condoms while taking PEP and until your follow-up HIV tests confirm that you have not acquired HIV. Your clinician will discuss any ongoing risk and may recommend other HIV prevention options, such as PrEP.
What is the difference between PEP and PrEP?
- PEP (Post-Exposure Prophylaxis) is taken after a possible exposure to HIV and is used in emergency situations. It must be started within 72 hours and taken for 28 days.
- PrEP (Pre-Exposure Prophylaxis) is taken before potential exposure to HIV and is used by people at ongoing risk of HIV. When taken correctly, PrEP is highly effective at preventing HIV.
I'm already taking PrEP, do I still need PEP?
Most people taking PrEP correctly do not need PEP. However, if you have missed enough PrEP doses that protection may have been reduced before a potential HIV exposure, you may need an assessment to determine whether PEP is appropriate. If you are unsure, contact a sexual health clinic as soon as possible for advice.
Does PEP protect against STIs?
No. PEP only helps prevent HIV infection. It does not protect against other sexually transmitted infections (STIs) such as gonorrhoea, chlamydia, syphilis, herpes or hepatitis. Condoms remain one of the most effective ways to reduce the risk of many STIs. If you are concerned about STIs, speak to a sexual health professional about testing.
Where can I get PEP?
PEP is available from:
- Sexual health clinics
- Some NHS emergency departments (A&E)
- Some urgent care services
Because PEP is time-sensitive, seek advice immediately if you think you may need it. Do not wait until symptoms develop.
Further Information
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