Post-exposure Prophylaxis (PEP) for HIV

Overview of Post-exposure Prophylaxis (PEP) for HIV

Post-exposure Prophylaxis (PEP) is a HIV prevention method that involves taking antiretroviral medicines after an exposure to HIV. PEP reduces the risk of infection. It must be taken within 72 hours of exposure (the sooner the better) to be effective.  If you are prescribed PEP, you will have take it once or twice daily for 28 days. PEP is effective in preventing HIV when administered correctly, but not 100%. 

How does PEP work?

PEP works by attacking the virus at the site of HIV exposure on the body and preventing the virus from multiplying in the infected cells.  The original infected cells will die naturally over time without producing more copies of HIV. This is why it is important to take PEP as soon as possible--you don’t want the HIV to replicate and spread throughout the body; once this happens, infection is permanent. 

Under what circumstances should you take PEP?

PEP should only be used in emergency situations and should not be your primary method of HIV prevention.  If you are having sex, safer sex products like condoms and dental dams are excellent HIV prevention methods if they are used correctly and consistently.  These products are free at Health Education and Promotion on the 3rd floor of the UC Davis Student Health and Wellness Center.  If you are at frequent, high risk for HIV, talk with your provider to see if PrEP (Pre-Exposure Prophylaxis) is a good option for you.

PEP may be right for you if:

  • You have shared needles with someone who might have HIV
  • One or more of your mucous membranes (eyes, mouth, vagina, rectum) have had direct contact with someone’s body fluid that might have HIV
  • An open wound came in direct contact with someone’s body fluid that might have HIV

Are there side effects?

Some potential side effects of taking PEP are prolonged headaches, diarrhea, nausea and vomiting.  Talk with your provider if you are experiencing these side effects so you can discuss solutions.

Where can you get PEP?

If you are concerned that you have been exposed to HIV, it is recommended that you immediately head to the nearest emergency room or urgent care if you would like to receive PEP.  PEP is also frequently found at HIV clinics.  Seeing your primary care physician may be an option, but only if they prescribe PEP (not all primary care providers do) and only if they can offer you an appointment immediately. 

Is PEP expensive?

If you were to pay for it out of pocket, PEP treatment could be very expensive, however, there are a number of options where you do not have to pay for PEP.  Many insurance plans will cover PEP and if you do not have insurance, your provider may be able to help you apply for medication assistance programs run by PEP manufacturers. 

If you have been potentially exposed to HIV because of your work, your workers’ compensation or employee health insurance plan will cover PEP treatment.  If you are prescribed PEP because of sexual assault and don’t have insurance you can also apply for reimbursement for clinical costs and medicines through the Office for Victims of Crime, funded by the US Department of Justice.


Centers for Disease Control and Prevention