How well does PrEP work?
PrEP is highly effective at stopping HIV infection. In studies, PrEP was more than 95% effective when taken correctly.
Globally, tens of thousands of people take PrEP and only a few HIV infections have been reported from when people were taking PrEP. Of these, two cases were due to drug resistant HIV which is rare when using the prescribed dose
This suggests that if you are taking PrEP as prescribed, it is likely to be close to 100% effective.
Last updated: 18 March 2019.