For receptive anal sex (bottoming), PrEP pills reach maximum protection from HIV at about seven days of daily use.
For receptive vaginal sex and injection drug use, PrEP pills reach maximum protection at about 21 days of daily use.
No data is available for PrEP pill effectiveness for insertive anal sex (topping) or insertive vaginal sex.
We don’t know how long it takes for PrEP shots to reach maximum protection during sex.