How effective is PrEP?

When taken as prescribed, PrEP – the HIV prevention pill – is highly effective! If you’re exposed to HIV while taking PrEP, the medicine can block HIV from taking hold in the body. In a major study of gay and bi men, as well as trans women, daily PrEP use lowered their risk of getting HIV by an estimated 99 percent – that’s pretty amazing!

If you decide to start PrEP, remember that it will take some time for the pill to reach maximum effectiveness – at least seven days for men who have sex with men, and longer if you are a woman having vaginal sex.

Find out if PrEP is right for you. Click here to find a PrEP-friendly provider near you. 


#AskTheHIVDoc is a video series from Greater Than AIDS featuring top HIV doctors providing answers to commonly-asked questions about HIV prevention, testing and treatment.

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While we make every effort to keep the medical information on our website updated, we cannot guarantee that the information reflects the most up-to-date research. Also, please note the views expressed by individuals who appear in Greater Than AIDS videos and other content are their own and are not made on behalf of any groups/organizations/associations.