HIV

Q: I am a heterosexual woman. I take PrEP every day but I heard that it still works if you only take it 4 times a week. Is that true?

The best and most effective way to take PrEP is to take it every day, 7 days a week; this is what we always recommend. It is true that results from some recent studies suggest that taking PrEP at least 4 times a week usually produces drug levels that are high enough to prevent HIV infection. But, these data are from studies of men who have sex with men, not from studies of women. And there are reasons to be very concerned that these results will not be true for women. In women, the levels of the drugs are more variable and in some tissues (like the vagina) they are a lot lower than in men's (anogenital tract). Thus, missing doses may seriously lessen the effects of PrEP. Until we have good data from studies of alternative dosing strategies for PrEP in women, we urge to you continue to take your PrEP every day.

(And we want to remind you that although daily PrEP is very effective at preventing HIV, it will not protect you from other sexually transmitted infections or from pregnancy. We recommend you continue to use condoms regularly, and see your provider every 3 months for STD and pregnancy tests.)