PEP stands for Post-Exposure Prophylaxis. This is antiretroviral medication (ART) which can be taken after potential exposure to HIV. The goal of taking to antiretroviral medication is to prevent the individual from becoming infected. PEP should be used only in emergency situations and must be started within 72 hours after a recent possible exposure to HIV. If someone has recently been exposed to HIV during sex, sharing needles for drug use or sexual assault, they should talk to their health care provider or an emergency room doctor about PEP immediately.