What is Post-Exposure Prophylaxis?
Post-Exposure Prophylaxis (PEP) involves taking anti-HIV medications as soon as possible after you may have been exposed to HIV to try to reduce the chance of becoming HIV positive. These medications keep HIV from making copies of itself and spreading through your body.
There are two types of PEP:
(1) occupational PEP (sometimes called "oPEP"), taken when someone working in a healthcare setting is potentially exposed to material infected with HIV, and
(2) non-occupational PEP (sometimes called “nPEP”), taken when someone is potentially exposed to HIV outside the workplace (e.g., from sexual assault, or during episodes of unprotected sex or needle-sharing injection drug use).
To be effective, PEP must begin within 72 hours of exposure, before the virus has time to make too many copies of itself in your body. PEP consists of 2-3 antiretroviral medications and should be taken for 28 days. Your doctor will determine what treatment is right for you based on how you were exposed to HIV. PEP is safe but may cause side effects like nausea in some people. These side effects can be treated and are not life threatening. PEP is not 100% effective; it does not guarantee that someone exposed to HIV will not become infected with HIV.
Who Needs Pep?
PEP is used for anyone who may have been exposed to HIV during a single event.
Healthcare workers are evaluated for PEP if they are exposed after:
- Getting cut or stuck with a needle that was used to draw blood from a person who may have HIV infection
- Getting blood or other body fluids that may have lots of HIV in their eyes or mouth
- Getting blood or other body fluids that may have lots of HIV on their skin when it is chapped, scraped, or affected by certain rashes
The risk of getting HIV infection in these ways is extremely low—fewer than 1 in 100 for all exposures.
PEP can also be used to treat people who may have been exposed to HIV during a single event unrelated to work (e.g., during episodes of unprotected sex, needle-sharing injection drug use, or sexual assault).
Keep in mind that PEP should only be used in uncommon situations right after a potential HIV exposure. It is not a substitute for other proven HIV prevention methods, such as correct and consistent condom use or use of sterile injection equipment.
Because PEP is not 100% effective, you should continue to use condoms with sex partners while taking PEP and should not use injection equipment that has been used by others. This will help avoid spreading the virus to others if you become infected.
When Should I Take Pep If I've Been Exposed?
To be effective, PEP must begin as soon as possible, but always within 72 hours of exposure. Your healthcare provider will consider whether PEP is right for you based on how you might have been exposed and whether you know if the person whose fluids you were exposed to might be HIV-positive. You will be asked to return for more HIV testing at 4 to 6 weeks, 3 months, and 6 months after the potential exposure to HIV. (Talk to your healthcare provider about the recommended follow-up schedule for you.)
For more information, see the Updated (2013) U.S. Public Health Service Guidelines for the Management of Occupational Exposures to Human Immunodeficiency Virus and Recommendations for Postexposure Prophylaxis (oPEP) or Nonoccupational Postexposure Prophylaxis (nPEP) Guidelines.
Where Can I Get Pep?
Some of the places you can go to seek treatment include your doctor’s office, emergency rooms, urgent care clinics, or a local HIV clinic.
Who pays for PEP?
Antiretroviral medications are expensive, and many people cannot pay for them out of pocket. If you are a healthcare worker who was exposed to HIV on the job, your workplace health insurance or workers’ compensation will usually pay for oPEP. If you are prescribed nPEP after sexual assault, you may qualify for partial or total reimbursement for medications and clinical care costs through the Office for Victims of Crime funded by the U.S. Department of Justice (see the contact information for each state). If you are prescribed nPEP for another reason, and you cannot get insurance coverage (private, employer-based, Medicaid, or Medicare), your healthcare provider can help you apply for free antiretroviral medications through the patient assistance programs of the drug manufacturers. Online applications can be faxed to the company, or some companies have special phone lines. These can be handled urgently in many cases to avoid delay in getting medicine. Learn more about patient assistance programs and co-pay programs for PEP.
Frequently Asked Questions
If I keep having unprotected sex with an HIV-positive partner, can I keep taking PEP to stay safe?
PEP should only be used immediately after an uncommon situation with potential HIV exposure. If you are frequently exposed to HIV, for example, because you often have sex without a condom with a partner who is HIV-positive, repeated uses of PEP is not appropriate. You may want to speak to your doctor about pre-exposure prophylaxis, or PrEP. PrEP is a pill taken daily for months to years that contains medications that keep HIV from making copies of itself and spreading infection through your body.
Why can’t PEP therapy be taken after 72 hours from the point of exposure?
Research has shown that PEP has little or no effect in preventing HIV infection if it is started more than 72 hours after HIV exposure. HIV makes copies of itself once it enters your body and it takes about three days for it to spread through your body. When HIV is only in a few cells where it entered the body, it can sometimes be stopped by PEP but when it is in many cells in many places in the body, PEP will no longer work.
- CDC – PEP Basics
- CDC – HIV in Healthcare Settings
- CDC – Proven HIV Prevention Methods
- Occupational Safety & Health Administration (OSHA) – Bloodborne Pathogens and Needlestick Prevention
- Veterans Administration (VA) – FAQs about PEP
- New York State Department of Health AIDS Institute – HIV Prophylaxis Following Occupational Exposure (October 2014 update)
- New York State Department of Health AIDS Institute – HIV Prophylaxis Following Non-Occupational Exposure (October 2014 update)
- WHO – Post-exposure Prophylaxis to Prevent HIV Infection
Last revised: 03/30/2015