PrEP (pre-exposure prophylaxis) is a new HIV prevention approach where HIV-negative individuals use anti-HIV medications to reduce their risk of becoming infected if they are exposed to the virus. The medications work to prevent HIV from establishing infection inside the body. PrEP has been shown to reduce the risk of infection for gay and bisexual men, transgender women, heterosexual men and women at high risk of HIV infection, and injection drug users. PrEP does not protect against other sexually transmitted infections (STIs).
Truvada is the medication currently approved by the FDA for PrEP. It is an oral pill taken once a day. It must be taken consistently to be effective. Truvada reduces risk of HIV infection 92%-99% when taken as directed. Missing a dose may result in a decrease in protection.