What is pre-exposure prophylaxis (PrEP)?

Pre-exposure prophylaxis (PrEP) is a novel HIV-prevention strategy that would use antiretrovirals (ARVs) to protect HIV-negative people from HIV infection. In this strategy, people would take the medications before they were exposed to HIV, in the hope that it would lower their risk of infection.

As their names suggest, post-exposure prophylaxis (PEP) and pre-exposure prophylaxis (PrEP) are very similar. They both use anti-HIV drugs (antiretrovirals or ARVs) to prevent an HIV infection establishing itself, but PrEP would be used before, rather than after, exposure or possible exposure to HIV.
