Is 7 days of PrEP enough?

Is 7 days of PrEP enough? Seven days of daily oral PrEP is the minimum time CDC identifies to reach high protection for receptive anal sex with Truvada or Descovy. For that exposure type, 7 days of consistent daily dosing builds enough drug in rectal tissue to provide strong protection, based on pharmacology studies. However, 7 days is not enough for receptive vaginal or front-hole sex, which needs about 20 to 21 days of daily dosing to reach protective levels in vaginal tissue. Also, taking PrEP for only 7 days and then stopping does not give ongoing protection. If you stop after 7 days, drug levels will fall within days, and you will not be protected for future exposures. If you had risk during those 7 days, you should continue for at least 28 days after last exposure. So 7 days can be enough to reach initial protection for anal sex if you continue daily after that, but it is not a complete course by itself. If you need emergency protection after an exposure in the past 72 hours, ask about PEP, not PrEP. A clinician can help time your start correctly.