Pre-exposure prophylaxis (or PrEP) is when people at very high risk for HIV take HIV medicines daily to lower their chances of getting infected. PrEP can stop HIV from taking hold and spreading throughout your body. It is highly effective for preventing HIV if used as prescribed, but it is much less effective when not taken consistently.
Daily PrEP reduces the risk of getting HIV from sex by more than 90%. Among people who inject drugs, it reduces the risk by more than 70%. Your risk of getting HIV from sex can be even lower if you combine PrEP with condoms and other prevention methods.