Information about pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP) is now available on MedlinePlus in both English and Spanish.

PrEP and PEP are medicines that work to prevent HIV, or human immunodeficiency virus. HIV is a serious condition that weakens your immune system, which can make you more likely to get infections and certain cancers.

In the U.S., HIV is most commonly transmitted through sex or contact with blood. The final stage of HIV is AIDS, or acquired immunodeficiency syndrome.

PrEP is a medication that people who are at high risk of HIV can take daily. PEP is for emergency situations, and should be taken within 72 hours of suspected exposure and for 28 days after.

You should contact your health care provider or go to an emergency room right away if you think you may have been exposed to HIV.