What is PEP and how fast do I need it?
Last updated September 3, 2026.
PEP is emergency HIV prevention after a possible exposure: daily antiretroviral pills for 28 days, and it must start within 72 hours - sooner is better, per the CDC, which says talk right away to a provider, ER doctor, or urgent care. Covered exposures: unprotected sex with a positive or unknown-status partner, a broken condom in that situation, shared injection equipment, sexual assault. Expect an HIV test at the visit, then the 28-day course with follow-up testing. PEP is not a substitute for ongoing prevention - repeated exposures belong on PrEP. Do not wait for Monday: emergency rooms stock it.
What to do
- Go the same day. ER, urgent care, or clinic - the 72-hour window is already running.
- Bring the exposure details. When, what kind, and what you know about the source.
- Take all 28 days. Stopping early forfeits the protection.
- Ask about PrEP afterward. If exposure risk continues, PrEP is the standing version.
Related questions
- Can an online doctor prescribe PEP?
- What is PrEP and who should take it?
- What is the window period for HIV testing?
- How soon after unprotected sex can I test for STIs?