Use of anti-HIV drugs to prevent infection with HIV

If a person is exposed to HIV during sex, many clinics are willing to provide them with a short-course of anti-HIV drugs to prevent infection. This is called post-exposure prophylaxis, or PEP for short. Not all clinics offer it for sexual exposure, pointing to worries about side-effects and resistance. Nevertheless, it is becoming more widely available. PEP is not a kind of ‘morning-after pill’ for HIV and it's not 100% effective.

PEP may also be considered in cases of rape and sexual assault where there is a risk of HIV transmission.

It is important to get and take PEP as soon as possible after possible exposure to HIV - ideally within four hours;  if not, within 24 hours if possible, and certainly within 72 hours (but many believe that this is too late).

If you are taking anti-HIV drugs and have unprotected sex with a person who is HIV-negative or whose HIV status you do not know, or if there is a condom accident during sex, you may be tempted to offer them some of your anti-HIV drugs in an attempt to reduce the risk of them becoming infected with HIV. This could involve risks. Some HIV drugs, particularly abacavir (Ziagen) and nevirapine (Viramune) can cause an allergic reaction or severe side-effects. There is also a chance that the person you are giving your HIV drugs to could already be infected with HIV and taking a few doses of your anti-HIV medicines could lead to resistance developing.

The thought that you may have exposed somebody to the risk of HIV infection is very worrying. If you do think that PEP might be appropriate, go to your local sexual health clinic as soon as possible. If this is closed then go to the accident and emergency department of your local hospital which should contact the on-call HIV doctor.