What is the difference between PrEP and PEP?

PrEP stands for Pre-exposure prophylaxis. It is an HIV prevention method for people who are HIV negative, but are at risk for contracting the HIV virus. PrEP is a daily combination of two HIV medicines sold under the name Truvada. Taking PrEP daily reduces the risk of contracting HIV from sex by more than 90% and contracting HIV from drug injection by more than 70%.

PEP stands for post-exposure prophylaxis.  PEP is a short-term treatment used to reduce the risk of HIV infection after exposure. This is to be used in emergency circumstances and must be started within 72 hours of recent HIV exposure. If prescribed PEP you must take it daily for 28 days.

Source Content:
AIDSinfo—aidsinfo.nih.gov
HIV.gov—www.hiv.gov