PrEP is medicine people at risk for HIV take to prevent getting HIV from sex or injection drug use.
PrEP reduces the risk of getting HIV from sex by about 99% when taken as prescribed.
PrEP reduces the risk of getting HIV from injecting drugs by at least 74% when taken as prescribed.
PrEP is much less effective when it is not taken as prescribed.
PrEP reaches maximum protection from HIV for receptive anal sex 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.