Protection before exposure
PrEP is medicine for people without HIV that reduces HIV risk when taken as prescribed. It does not prevent other sexually transmitted infections.
How effective is it?
When taken as prescribed, PrEP reduces the risk of acquiring HIV through sex by about 99%, according to CDC. This estimates effectiveness; it is not a guarantee for each exposure. Missed doses can reduce protection. PrEP is not emergency treatment after an exposure that has already happened and does not prevent other STIs.
Daily or event-based?
Daily dosing is one option. Event-based dosing is not appropriate for everyone or every exposure; discuss it with a clinician. Do not start or change a regimen without a consultation.
Before you start
Confirmation that you do not have HIV is essential. Before oral PrEP, kidney function and hepatitis B are assessed, alongside other STI tests according to exposure. Tests depend on the medicine, your health and recent PrEP or PEP use. A clinician determines the appropriate plan.
Ongoing care
PrEP requires regular HIV testing and follow-up. The team will explain dosing, testing, access to medication and what to do after missed doses.
Pregnancy and family planning
If you are pregnant, breastfeeding or planning pregnancy, discuss this before starting or changing PrEP. Some regimens may be used after clinical assessment; the choice depends on individual benefits, risks and testing.