PrEP vs PEP – which HIV prevention is which?
The difference between PrEP before possible HIV exposure and PEP after a possible exposure, with the time-sensitive next steps in South Africa.
PrEP is before; PEP is after
PrEP is pre-exposure prophylaxis: medicine used by an HIV-negative person before ongoing or anticipated exposure risk. PEP is post-exposure prophylaxis: an urgent course considered after a possible exposure. They are different pathways, and testing and clinical assessment are needed before starting either one.
Do not wait when an exposure may have happened
- PrEP is planned prevention and needs HIV testing and ongoing follow-up.
- PEP is time-sensitive after a possible exposure to blood or sexual fluids; seek care immediately.
- A clinician checks the exposure, HIV status, other infections, pregnancy possibility and medicine interactions.
- Neither PrEP nor PEP protects against every STI or pregnancy.
The formulary includes the combination used in some HIV prevention pathways; a clinician must confirm suitability:
Tenofovir / Emtricitabine (TDF/FTC) — Truvada, Ricovir-EM
HIV-1 infection (NRTI backbone); HIV pre-exposure prophylaxis (PrEP)
Choose the right pathway
- Write down when and how the possible exposure happened.
- Go to a clinic, emergency service or other approved HIV-care pathway as soon as possible.
- Ask for HIV testing and the correct prevention plan.
- Follow the course and return for the tests and review you are given.
Possible exposure is time-sensitive
Common questions
- What is the difference between PrEP and PEP?
- PrEP is prevention taken before possible exposure. PEP is an urgent treatment pathway considered after a possible exposure and needs prompt clinical assessment.
- Can I use PrEP as PEP?
- Do not repurpose a PrEP supply after an exposure. A clinician must assess the event and prescribe the appropriate PEP pathway and follow-up.
Sources
- National Consolidated Guidelines for the Management of HIV in Adults, Adolescents, Children and InfantsNational Department of Health, South Africa
- Primary Healthcare Standard Treatment Guidelines and Essential Medicines ListNational Department of Health, South Africa
Last reviewed 26 August 2026.