Drawbacks of post-exposure prophylaxis

Published: 07 April 2009

Despite the apparent success of PEP, it is difficult to assess the risk of infection associated with each exposure, especially in cases where the HIV status of the source is not known. In addition, research suggests the uptake of PEP is often quite low and that many people who do accept PEP fail to attend follow-up appointments or do not fully adhere to their drug regimen.1 2

Low completion rates may be due to the frequency of side-effects associated with PEP in several studies. For example, six of nine healthcare workers at St Bartholomew’s Hospital, London, who commenced a combination of AZT (zidovudine, Retrovir), 3TC (lamivudine, Epivir), and indinavir (Crixivan) did not complete four weeks of indinavir therapy, although there were no discontinuations among the five people who received saquinavir (Invirase).3

Similar rates of non-completion have been observed in other studies of healthcare workers, ranging from 17 to 47%.4 5 6 7 8 9 The most commonly reported side-effects are nausea, tiredness, and feeling unwell, with around a quarter of people stopping PEP doing so because of these side-effects.

Poor levels of adherence can also be caused by psychological factors, such as patients being reminded of his or her risk of HIV transmission. This is reflected in the observation that victims of sexual assault have particularly poor adherence levels.10 11 12 13 14

The efficacy of PEP can also be limited if the virus is resistant to the drugs in the regimen. Furthermore, poor adherence to PEP drugs may put people at risk of developing resistance to the drugs being used, limiting their future treatment options if they seroconvert.


  1. Lacombe K et al. Determinants of adherence to non-occupational post HIV exposire prophylaxis. AIDS 20: 291-293, 2006
  2. Myles JE et al. Postexposure prophylaxis for HIV after sexual assault. JAMA 284: 1516-1518, 2000
  3. Parkin J et al. Tolerability and side-effects of post-exposure prophylaxis for HIV infection. Lancet 355: 722-723, 2000
  4. Wang SA et al. Experience of health-care workers taking post-exposure prophylaxis after occupational human immunodeficiency virus exposures: findings of the HIV Postexposure Prophylaxis Registry. Infect Control Hosp Epidemiol 21: 780-785, 2001
  5. Swotinsky RB et al. Occupational exposure to HIV: experience at a tertiary care center. J Occup Environ Med 42: 1102-1108, 1998
  6. Lee LM et al. Tolerability of postexposure antiretroviral prophylaxis for occupational exposures to HIV. Drug Saf 24: 587-597, 2001
  7. Russi M et al. Antiretroviral prophylaxis of health care workers at two urban medical centers. J Occup Environ Med 42: 1092-1100, 2000
  8. Garb JR One-year study of occupational human immunodeficiency virus postexposure prophylaxis. J Occup Environ Med 44: 265-270, 2002
  9. Grime PR et al. Pan-Thames survey of occupational exposure to HIV and the use of post-exposure prophylaxis in 71 NHS trusts. J Infect 42: 27-32, 2001
  10. Bamberger JD et al. Postexposure prophylaxis for human immunodeficiency virus (HIV) infection following sexual assault. Am J Med 1065: 323-326, 1999
  11. Claydon E et al. Rape and HIV. Int J STD AIDS 2: 200-201, 1991
  12. Wiebe ER et al. Offering prophylaxis to people who have been sexually assaulted: 16 months' experience in a sexual assault service. CMAJ 162: 641-645, 2000
  13. Olshen E et al. Use of human immunodeficiency virus postexposure prophylaxis in adolescent sexual assault victims. Arch Pediatr Adolesc Med 160: 674-680, 2006
  14. Neu N et al. Postexposure prophylaxis for HIV in children and adolescents after sexual assault: a prospective observational study in an urban medical center. Sex Transm Dis (online edition), 2006
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

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.

NAM’s information is intended to support, rather than replace, consultation with a healthcare professional. Talk to your doctor or another member of your healthcare team for advice tailored to your situation.