How effective is PrEP?
PrEP is highly effective for preventing HIV.
- PrEP reduces the risk of getting HIV from sex by about 99% when taken daily as prescribed.
- Although there is less information about how effective PrEP is among people who inject drugs, we do know that
PrEP reduces the risk of getting HIV by at least 74% when taken daily as prescribed.
- PrEP is much less effective when it is not taken daily as prescribed.
How long do I have to take PrEP before it is highly effective?
- PrEP reaches maximum protection from HIV for receptive anal sex (bottoming) at about 7 days of daily use.
- For receptive vaginal sex and injection drug use, PrEP reaches maximum protection at about 21 days of daily use.
- No data are available for insertive anal sex (topping) or insertive vaginal sex.