Skip to main navigation Skip to main content

PrEP as HIV Prevention

Pre-exposure prophylaxis (or PrEP) is a way for people who do not have HIV but who are at very high risk of getting HIV to prevent HIV infection by taking a pill every day. The pill (brand name Truvada) contains two medicines (tenofovir and emtricitabine) that are used in combination with other medicines to treat HIV. When someone is exposed to HIV through sex or injection drug use, these medicines can work to keep the virus from establishing a permanent infection.

When taken daily, PrEP is highly effective for preventing HIV. Studies have shown that PrEP reduces the risk of getting HIV from sex by about 99% when taken daily. Among people who inject drugs, PrEP reduces the risk of getting HIV by at least 74% when taken daily. PrEP is much less effective if it is not taken consistently.

People who use PrEP must commit to taking the drug every day and seeing their health care provider for follow-up every 3 months.

Since PrEP does not protect against other STDs, use condoms the right way every time you have sex.

CDC PrEP

HIV Treatment as Prevention

People with HIV should take medicine to treat HIV as soon as possible. HIV medicine is called antiretroviral therapy, or ART. If taken as prescribed, HIV medicine reduces the amount of HIV in the body (viral load) to a very low level, which keeps the immune system working and prevents illness. This is called viral suppression—defined as having less than 200 copies of HIV per milliliter of blood. HIV medicine can even make the viral load so low that a test can’t detect it. This is called an undetectable viral load. 

Getting and keeping an undetectable viral load* is the best thing people with HIV can do to stay healthy. Another benefit of reducing the amount of virus in the body is that it helps prevent transmission to others through sex or syringe sharing, and from mother to child during pregnancy, birth, and breastfeeding. This is sometimes referred to as treatment as prevention. There is strong evidence about treatment as prevention for some of the ways HIV can be transmitted, but more research is needed for other ways.

CDC HIV Treatment as Prevention

HIV Treatment Can Prevent Sexual Transmission (CDC)

Evidence of HIV Treatment and Viral Suppression in Preventing the Sexual Transmission of HIV (CDC)