Post-exposure prophylaxis

  • Post-exposure prophylaxis (PEP) is a four-week course of HIV medication that may block HIV infection.
  • Very few cases of HIV transmission have occurred after use of PEP.
  • PEP is most commonly used by healthcare workers after needlestick injuries, and by people following sexual exposure.

Post-exposure prophylaxis (PEP) is a course of HIV medication that may block HIV infection. Although no antiretroviral has been licensed for use as prophylaxis against HIV infection, PEP is offered to people after a possible exposure to HIV.

PEP only works if treatment is started soon enough after exposure and lasts long enough, usually around four weeks. Therefore, it should not be considered as a ‘morning-after pill’ for HIV, as a full course of PEP requires consistent adherence over many weeks, often in the face of side-effects, at a time that may be stressful.

Treatment does not need to continue indefinitely because the aim of treatment is to prevent HIV from entering cells in the body: infection will either become established or will be aborted within that period. It can take HIV between one and five days to become established in the CD4 T-cells and lymph nodes after exposure.1 2 It is thought that PEP acts during this time to prevent the virus from taking hold, thus preventing seroconversion in the person who was exposed.


  1. Saag MS et al. Candidate antiretroviral agents for use in post exposure prophylaxis. Am J Med 102: 25-31, 1997
  2. Spira AI et al. Cellular targets of infection and route of viral dissemination after an intravaginal inoculation of simian immunodeficiency virus into rhesus macaques. J Exp Med 183: 215-225, 1996
This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.
Community Consensus Statement on Access to HIV Treatment and its Use for Prevention

Together, we can make it happen

We can end HIV soon if people have equal access to HIV drugs as treatment and as PrEP, and have free choice over whether to take them.

Launched today, the Community Consensus Statement is a basic set of principles aimed at making sure that happens.

The Community Consensus Statement is a joint initiative of AVAC, EATG, MSMGF, GNP+, HIV i-Base, the International HIV/AIDS Alliance, ITPC and NAM/aidsmap