If you think that you have been exposed to HIV from having a one off incident of unprotected sex or a condom breaking then there is a course of medication that you can take which may prevent you becoming HIV positive.

Post-exposure Prophylaxis (PEP) is a four week course of anti HIV medication that must be taken within 72 hours of possible exposure.  The course of treatmentmay have side effects such as nausea, diarrhoea and feeling tired or unwell.

It should not be thought of as a ‘morning after pill’ for HIV.

PEP is not guaranteed to work in 100% of cases but the sooner you can get access to the treatment after the possible exposure, the more likely it is to work. 

You can only access PEP up to a maximum of 72 hours following possible exposure and is not likely to be effective after this time.

The course of treatment is available from sexual health clinics and also from A&E departments.  If you think you have been exposed to HIV then you should speak to a sexual health clinic as soon as possible. Your GP cannot issue PEP.

As well as how at risk you are, other factors are considered such as whether you have symptoms of other STIs or if the person you believe has passed it on to you is known to have HIV. This is whether you're giving/active/top or taking/passive/bottom.

When would PEP be given?

  • It would only be recommended within 72 hours of the exposure/risk/sex
  • The earlier into that 72 hour period the more potential it has for being effective
  • Recommendations for giving PEP are for unprotected sex, the condom breaking (condom failure) or for oral sex where the person presenting for PEP was giving the oral sex not receiving it
  • If the ‘source’ individual has HIV
  • If the status of the ‘source’ individual is unknown and there has been unprotected sex if the sex was receptive and the ‘source’ is from an area of high HIV prevalence (you’ve had unprotected sex, bottom not top in an area with high HIV rate)
  • Sexual assault – aggravated sexual intercourse increases risk (more chance of tears etc, increasing routes of transmission) and therefore PEP may be more readily considered

Other factors that may influence

Where there’s another STI present (the person presenting knows they have one or they have symptoms), whether or not the person presenting has a foreskin/is circumcised may affect the level of risk and therefore whether PEP is considered effective.

What will happen if you’re given PEP?

  • Discussion around risks, side effects and how to take them
  • Offered a rapid test with pre-test discussion
  • Seen at GUM/HIV department asap to see a clinical expert
  • Possible need to continue with further 4 weeks of meds if result is negative
  • Need for 12 week HIV test following PEP completion (HIV can take 12 weeks following infection to show on a test)
  • Need to have safer sex/use of condoms and lube
  • Disclosure of status
  • Coping strategies
  • Counselling / support services / social support

Source for the majority of this article: ‘UK guideline for the use of post-exposure prophylaxis for HIV following sexual exposure 2011’ BASHH PEPSE Guidelines.