Learning About HIV Post-Exposure Prevention (PEP)

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What is post-exposure prevention (PEP)?

HIV (human immunodeficiency virus) is a virus that attacks the immune system. This is the body's natural defense system. Without a strong immune system, the body has trouble fighting off disease.

If you have come into contact with HIV, treatment with medicine can help prevent the virus from taking hold and spreading in your body. This treatment is called post-exposure prophylaxis (PEP). It's only for people who have been exposed to the virus but aren't yet infected. It must be started quickly after exposure.

You can be exposed to HIV in several ways. A few of the most common ways are:

  • During sex (for example, if the condom broke) with someone who has HIV. This includes vaginal, anal, and oral sex.
  • Sexual assault.
  • Sharing a needle, syringe, or other drug equipment with someone who has HIV.

Many people are infected with HIV but don't know it. If you can, find out if the other person knows their HIV status.

If you are sometimes at risk of being infected with HIV, talk with your doctor about taking medicines that may lower your risk. This treatment is called pre-exposure prophylaxis (PrEP).

How is it given?

PEP must be started as soon as possible after you've been exposed to HIV, but no later than 3 days (72 hours) after.

One of the first things your doctor will do is make sure you don't already have the virus. This is done with an HIV test. Your doctor won't wait for the test results to come back before starting treatment. You may also get tests to see if you were exposed to a sexually transmitted infection (STI) or hepatitis. You may get a pregnancy test. Your doctor may give you medicines to prevent STIs and pregnancy.

PEP treatment lasts 28 days. It's usually 1 or more pills taken once a day. Don't stop taking the medicine without talking to your doctor.

You'll get another HIV test at the end of your treatment. It's to make sure that the PEP worked.




The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.