Updated 17 October 2016

Post-exposure prophylaxis (PEP)

Want to know more about Post-exposure prophylaxis (PEP)? Dr Avron Urison from AllLife explains what it is and how it works.


Want to know more about Post-exposure prophylaxis (PEP)? Dr Avron Urison from AllLife explains what it is and how it works. 

Post-exposure prophylaxis (PEP) is a short-term anti-retroviral (ARV) treatment that reduces the likelihood of HIV infection after exposure to HIV-infected blood or sexual contact with an HIV-positive person.

Where infection occurs as a result of exposure, ARV treatment should begin before the infected cells settle in the lymph nodes. Lymph nodes are organs that contain white blood cells, and they are important in the proper functioning of the immune system.

The treatment, which can be accessed from clinics and health centres in South Africa can prevent the virus from becoming established in the body of someone who has been exposed. PEP is particularly important for people who have been sexually assaulted or people who have been exposed to blood through a needle injury or other accident at work. Post-exposure prophylaxis is part of a growing trend in using antiretroviral medicine as a preventative measure, along with pre-exposure prophylaxis and treatment as prevention.

How does it work?

Post-exposure prophylaxis is antiretroviral drug treatment that is started immediately after someone is exposed to HIV.  The aim is to allow a person’s immune system a chance to provide protection against the virus and to prevent HIV from becoming established in someone’s body. It usually consists of a month long course of two or three different types of the antiretroviral drugs that are also prescribed as treatment for people living with HIV.

There is no medical agreement on the time limit for administering PEP. Some healthcare workers suggest beginning PEP 24-36 hours after possible exposure to HIV through rape or unprotected sex, other international guidelines suggest 24-48 hours. South African policy advises that PEP should be administered within 72 hours after the potential exposure to HIV. The drug regimen for PEP consists of a combination of ARV mediations that are taken a period of four weeks.

Who can benefit

People exposed to blood or bodily fluids at work: It is a common occurrence for people to be exposed to blood or bodily fluids in occupational circumstances, particularly for health care workers.

•    Victims of rape or sexual assault: PEP is especially important for individuals who have been sexually assaulted, as they could be particularly vulnerable to skin tearing that comes with aggravated sexual intercourse. It has been found that there are often low rates of adherence to PEP among victims of sexual assault, potentially due to stigma, trauma following rape and assault, treatment side effects and a lack of support.

•    People who may have been exposed to HIV through consensual sexual contact: PEP may be recommended if it is known that the sexual partner has HIV. Otherwise, it is often not recommended, as risks may outweigh the benefits.  This can vary depending on the setting, or whether the sexual partner is from a ‘high-risk group’. PEP would rarely be recommended in cases of non-penetrative sex.

•    People potentially exposed through needles: For people who have shared needle equipment, if it is known that the other person who used the needle has HIV then PEP may be recommended. For people who have had a needlestick injury from a discarded needle outside of a healthcare setting, PEP is not usually recommended, because the virus cannot survive long outside of the human body so it is very unlikely that the needle could infect somebody.


As with most antiretrovirals, post-exposure prophylaxis can cause side effects such as diarrhoea, headaches, nausea, vomiting and fatigue. Some of these side effects can be quite severe and it is estimated that 1 in 5 people give up the treatment before completion. There is also the risk that taking PEP may cause a person to develop drug resistance should the patient become infected with HIV and need to be treated with antiretrovirals. Therefore it is a good idea to know your HIV status before starting PEP.

Post-exposure prophylaxis is not going to be enough to significantly reduce the worldwide spread of HIV. It is a short-term preventative measure that is used as an ‘emergency’ precaution. PEP is considered as the very last resort in HIV prevention and should only be used when all other methods of HIV prevention have failed. However, with increasing widespread availability and further awareness, PEP can offer more people a way to reduce the risk of HIV infection, especially in cases of sexual assault or where the status of the partner is known.

So, in summary, in order to make sure that PEP treatment is effective and to prevent HIV infection, one should:

  • start PEP treatment as soon as possible, but no later than 72 hours after  the incident
  • take every dose of the medication as prescribed for 28 days
  • be tested and treated for other sexually transmitted infections (if indicated)
  • be tested for pregnancy (if indicated)
  • if reported early morning after pill to prevent chances of getting pregnant should be given (if indicated)
  • practice safe sex for at least six months after the incident
  • return to the health facility for follow-up tests and counselling at six weeks, three months, six months, and one year after the incident 

(Dr Avron Urison, Medical Director at AllLife Pty Ltd - providers of life insurance for HIV positive individuals)  


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Dr Sindisiwe van Zyl qualified at the University of Pretoria before working for an HIV/AIDS NPO in Soweto for many years. She was named one of the Mail & Guardian's Top 200 Young South Africans in 2012.

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