Pre-Exposure Prophylaxis

Key facts

• PrEP is a daily antiretroviral regimen taken by HIV-negative people at substantial risk of acquiring HIV.
• Taken consistently, it cuts the risk of sexually transmitted HIV by around 99%.
• The standard regimen combines tenofovir and emtricitabine in a single daily tablet, blocking the enzyme HIV needs to replicate inside human cells.
• PrEP sits within a broader HIV prevention plan alongside regular testing every three months, screening for other STIs, and condom use.

How PrEP works

The standard regimen combines two antiretrovirals, tenofovir and emtricitabine, taken together as a single daily tablet. Both drugs block the reverse transcriptase enzyme that HIV uses to replicate inside human cells. Because the drugs are already present in tissue when exposure happens, the virus can't establish an infection.

PrEP is part of a broader approach to HIV prevention and is typically used alongside regular HIV testing (every three months), screening for other sexually transmitted infections, and condom use. People taking PrEP also need periodic kidney function checks, since tenofovir can affect the kidneys over time. PrEP protects against HIV only, not other sexually transmitted infections, which is why ongoing STI screening and condom use remain part of the plan.

Who benefits from PrEP

PrEP suits HIV-negative adults in higher-risk groups, including men who have sex with men, serodiscordant couples (where one partner is HIV-positive), people who inject drugs, and anyone with a recent history of a sexually transmitted infection. Some men who have sex with men use an on-demand dosing schedule timed around sexual activity instead of a daily tablet, though the daily regimen remains the option most widely recommended. Starting PrEP requires a confirmed negative HIV test, and ongoing negative results are needed to continue treatment.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.