PrEP: pre-exposure prophylaxis

How PrEP works

PrEP puts HIV medication in your body before any exposure, so that if the virus enters, it cannot take hold and multiply. It only protects against HIV — not against other sexually transmitted infections or pregnancy — so many people use it alongside condoms and regular STI testing.

PrEP is different from PEP, which is emergency medication taken after a possible exposure. PrEP is ongoing, planned protection; PEP is a short course started quickly after the fact.

Read more about PEP →

The options

PrEP is available in more than one form, and which options exist depends on your country and local health service:

• Daily oral PrEP — a tablet taken every day. This is the most widely available form and has years of real-world evidence behind it.
• On-demand (event-based) oral PrEP — a specific dosing schedule around sex, used by some people in certain circumstances and under medical guidance.
• Long-acting injectable PrEP — administered by a healthcare provider at set intervals rather than daily. Newer long-acting options have expanded the choices available in some countries.

A healthcare provider can explain which options apply where you live and which suits your situation.

Who PrEP is for

PrEP is worth discussing with a clinician if you may be exposed to HIV — for example if you have a partner living with HIV who is not yet virally suppressed, if you don't always use condoms with partners whose status you don't know, or if you share injecting equipment. Guidelines encourage providers to make PrEP available to anyone who asks about it.

How effective is it?

When taken as prescribed, PrEP is highly effective at preventing HIV. Its protection depends on taking it correctly and consistently, which is one reason long-acting options appeal to people who find a daily routine difficult.

PrEP and HIV testing

Testing is part of PrEP, not separate from it. You need a negative HIV test before starting, because PrEP is for people who don't have HIV — starting it during an undetected infection isn't appropriate. People on PrEP also test regularly while using it.

See how the window period works →

If you are considering PrEP, knowing your current status is the first step. You can check it privately at home. The INSTI HIV Self Test detects HIV-1 and HIV-2 antibodies from a single drop of blood, with results in about 60 seconds. In an untrained user study by bioLytical Laboratories, it showed 100% sensitivity and 99.8% specificity. It is CE-marked for self-testing in Europe and WHO Prequalified. A self-test is a useful first step, but starting PrEP itself is done with a healthcare provider, who will arrange confirmatory testing and ongoing monitoring.

If you want a calm, private way to know where you stand before that conversation, testing is a good place to begin.