WHAT IS POST-EXPOSURE PROPHYLAXIS?
Prophylaxis means disease prevention. Post-exposure prophylaxis (or PEP) means taking antiviral medications as soon as possible after exposure to HIV, so that the exposure will not result in HIV infection. These medications are only available with a prescription. PEP should begin within as soon as possible after exposure to HIV but certainly within 72 hours. Treatment with 2 or 3 antiviral drugs should continue for 4 weeks, if tolerated.
WHO SHOULD USE PEP?
PEP has been standard procedure since 1996 for healthcare workers exposed to HIV. Workers start taking medications within a few hours of exposure. Usually the exposure is from a "needle stick," when a health care worker accidentally gets jabbed with a needle containing HIV-infected blood. PEP reduced the rate of HIV infection from workplace exposures by 79%. However, some health care workers who take PEP still get HIV infection.
In 2005, the Centers for Disease Control reviewed information on PEP. They concluded that it should also be available for use after HIV exposures that are not work-related. People can be exposed to HIV during unsafe sexual activity, when a condom breaks during sex, or if they share needles for injecting drugs. Infants can be exposed if they drink breast milk from an infected woman. In a study of PEP in 400 cases of possible sexual exposure to HIV, not one person became infected with HIV.
SHOULD PEP BE USED FOR NON-OCCUPATIONAL EXPOSURE?
HIV exposure at work is usually a one-time accident. Other HIV exposures may be due to unsafe behaviors that can occur many times. Some people think that PEP might encourage this unsafe behavior if people think that PEP is an easy way to avoid HIV infection.
There are other reasons why PEP might not be a good idea for non-occupational exposure:
Despite these concerns, there is growing interest in PEP for non-occupational exposure. Most programs include counseling to inform and encourage people to avoid exposure to HIV.
- There is no research to show that PEP works for non-occupational exposure. We don't know how soon after exposure to HIV someone has to start PEP.
- PEP is not a "morning-after pill." It is a program of several drugs, several times each day, for at least 30 days. PEP costs between $600 and $1,000.
- For best results, you have to take every dose of every PEP medication. Missing doses could mean that you develop HIV infection. It could also allow the virus to develop resistance to the medications. If that happens they would no longer work for you.
- The medications have serious side effects. About 40% of health care workers did not complete PEP because of the side effects.
HOW IS PEP TAKEN?
PEP should be started as soon as possible after exposure to HIV. The medications used in PEP depend on the exposure to HIV. The following situations are considered serious exposure:
- Exposure to a large amount of blood
- Blood came in contact with cuts or open sores on the skin
- Blood was visible on a needle that stuck someone
- Exposure to blood from someone who has a high viral load (a large amount of virus in the blood).
For serious exposures, the U.S. Public Health Service recommends using a combination of three approved antiviral drugs for four weeks. For less serious exposure, the guidelines recommend four weeks of treatment with two drugs: AZT and 3TC.
In January 2001, the Centers for Disease Control warned against using nevirapine for PEP because of the risk of liver damage. See Fact Sheet 431 for more information on nevirapine. The CDC has not updated its PEP recommendations since 2001.
WHAT ARE THE SIDE EFFECTS?
The most common side effects from PEP medications are nausea and generally not feeling well. Other possible side effects include headaches, fatigue, vomiting and diarrhea. For more information, see the fact sheets on individual antiviral medications.
THE BOTTOM LINE
Post-exposure prophylaxis (PEP) is the use of antiviral drugs as soon as possible after exposure to HIV, to prevent HIV infection. PEP can reduce the rate of infection in health care workers exposed to HIV by 79%.
The benefits of PEP for non-occupational exposure have not been proven. This use of PEP is controversial because some people fear it will encourage unsafe behaviors.
PEP is a four-week program of two or three antiviral medications, several times a day. The medications have serious side effects that can make it difficult to finish the program. PEP is not 100% effective; it can not guarantee that exposure to HIV will not become a case of HIV infection.