PEP
Post exposure prophylaxis (PEP) is anti-HIV medication that is prescribed to a HIV negative person, after a potential exposure to HIV, to protect them from being infected with HIV. It should be started within 72 hours of the exposure, the earlier the better. It won’t usually be prescribed after 72 hours. PEP needs to be taken daily for 28 days.
Evidence suggests PEP reduces the chances of HIV infection by approximately 80%. It is not a cure for HIV and it doesn’t work in all cases in preventing HIV transmission: some strains of HIV aren't affected by the medicine. Also if you don’t take it correctly or start it too late it may fail to protect you.
PEP can be provided in A and E departments or sexual health services.
It can have some side effects, such as tiredness, sickness, diarrhoea, and headache.
PEP may be considered or recommended in the following circumstances
1. If your partner is HIV positive AND:
- you had unprotected anal sex with them OR
- you had unprotected vaginal sex with them OR
- you shared their equipment for injecting drugs
2. Your partner’s HIV status is unknown or unclear, but they belong to a group where the rates of HIV are high. Such high risk groups include gay or bisexual men; those who have migrated to the UK from countries with high HIV prevalence (ie >1%), eg Sub Saharan Africa; Injecting drug users from high risk countries such as Eastern Europe and Central Asia AND:
- you had unprotected anal sex with them OR
- you had unprotected vaginal sex with them OR
- you shared their equipment for injecting drugs
If you have an HIV positive partner and they have been on HIV treatment for more than 6 months and they have been taking it properly with an undetectable viral load you probably won’t need PEP. In this situation the risk of catching HIV (if they are your only partner) is near to zero.
The following risks do not usually warrant PEP: human bites, semen splash to the eye, oral sex.
But… there are many factors that are involved in deciding whether you require PEP after an exposure or not so if in doubt attend A and E or a sexual health clinic as soon as possible.
Before you are given PEP you need to have a HIV test. This is because if you are already HIV positive we need to do further tests to rule out drug resistance, before starting treatment on you.
You will need to have further HIV tests after completing the PEP course to confirm you have not been infected. It is also recommended you have testing for other blood borne infections like hepatitis B and hepatitis C as well as a full sexual transmitted infection screen (chlamydia, syphilis and gonorrhoea).
Additional Links