See our guide to what to do after a condom breaks or unprotected sex for the broader next-steps picture — this page focuses specifically on PEP itself, since understanding the timing matters more here than almost anywhere else on this site.
What it is
PEP (post-exposure prophylaxis) is emergency medication that can prevent HIV from establishing an infection after a specific exposure — a needle-stick, a broken condom with a partner of unknown or positive HIV status, or another situation with a real, specific risk. It must start within 72 hours of the exposure to be effective, and effectiveness is meaningfully better the sooner it's started within that window — not something to research extensively before acting if the window is closing.
How it's different from PrEP
See our full PrEP guide for the ongoing, before-exposure version of HIV prevention medication. PEP is specifically for after a known or suspected exposure has already happened, as an emergency measure — the two aren't interchangeable, and PEP isn't meant to substitute for PrEP as an ongoing strategy if exposure risk is recurring.
What the course involves
Commonly a 28-day course of medication, taken consistently for the full duration even if it starts to feel unnecessary partway through — stopping early undermines how well it works. Follow-up HIV testing after completing the course is a standard part of the process, to confirm the outcome.
Where to actually get it
Emergency rooms, sexual health clinics, and some doctors can prescribe PEP. Given the time sensitivity, this is a genuine "call ahead or go in directly" situation rather than one to spend time extensively researching first — every hour that passes within the 72-hour window matters.
Frequently asked questions
How is PEP different from PrEP?
PrEP is taken before potential exposure, on an ongoing basis, to prevent HIV. PEP is taken after a specific exposure has already happened, as an emergency measure within a narrow time window — the two are not interchangeable, and PEP isn't meant to be used as a routine substitute for PrEP.
How long is a PEP course?
Commonly a 28-day course of medication, taken as prescribed for the full duration even if it feels unnecessary partway through — stopping early undermines its effectiveness.
Where can PEP actually be accessed?
Emergency rooms, sexual health clinics, and some doctors can prescribe it — given the time sensitivity, this is a situation to call ahead or go in directly rather than researching extensively first.
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