Post-Exposure Prophylaxis

Content From: HIV.govUpdated: November 15, 20235 min read


PEP (or post-exposure prophylaxis) involves taking anti-HIV drugs very soon after a possible exposure to HIV to prevent HIV.

What Is PEP?

HIV PEP, or post-exposure prophylaxis, is a short course of HIV medicines taken very soon after a possible exposure to HIV to prevent the virus from taking hold in your body.

You must start it within 72 hours (3 days) after a possible exposure to HIV, or it won’t work. Every hour counts!

PEP should be used only in emergency situations. It is not meant for regular use by people who may be exposed to HIV frequently.

How Do You Know If You Need PEP?

PEP may be right for you if you are HIV-negative or don’t know your HIV status, and you think you may have been exposed to HIV in the last 72 hours:

  • During sex (for example, you had a condom break with a partner of unknown HIV status or a partner with HIV who is not virally suppressed)
  • Through shared needles, syringes, or other equipment used to inject drugs (for example, cookers)
  • Through sexual assault
  • Through a possible workplace exposure, such as from needlestick injury. Workplace HIV transmission is extremely rare.

Where Can You Get PEP?

If you think you were recently exposed to HIV, contact a health care provider immediately or go to an emergency room or urgent care clinic right away.

Your health care provider, an urgent care provider, or emergency room doctor will evaluate you, help you decide whether PEP is right for you, and work with you to determine which medicines to take for PEP. Use the Locator to find PEP services near you. In some states, pharmacists can also prescribe PEP (Arkansas, California, Colorado, Illinois, Maine, Nevada, New Mexico, New York, North Carolina, Oregon, Utah, and Virginia.) Read moreExit Disclaimer.

How Long Do You Need to Take PEP?

If you are prescribed PEP, you will need to take the HIV medicines every day for 28 days. It is important to take all the doses as prescribed to give PEP the best chance of working.

You will also need to return to your health care provider at certain times while taking PEP and after you finish taking it for follow-up HIV testing at 4 to 6 weeks and at 3 months and for other lab tests.

How Well Does PEP Work?

PEP is effective in preventing HIV infection when it’s taken correctly, but it’s not 100% effective. The sooner you start PEP after a possible HIV exposure, the better.

While taking PEP, it’s important to use other HIV prevention methods, such as using condoms the right way, every time you have sex and using only new, sterile needles and works when injecting drugs.

Doxy-PEP: Medicine to Prevent Sexually Transmitted Infections (STIs)

There is another form of PEP that is effective at preventing STIs. A research study found that the oral antibiotic doxycycline reduced STIs by two-thirds when tested among men who have sex with men (MSM) and transgender women, including people with HIV, who took the medication within 72 hours of having condomless sex. This prevention approach is called doxy-PEP or STI PEP. However, the research also showed a slight increase in antibacterial resistance. Doxy-PEP does not prevent HIV. Talk to your provider about whether doxy-PEP is right for you to prevent STIs.

Does PEP Cause Side Effects?

PEP is safe, but the HIV medicines used for PEP may cause side effects like nausea in some people. In almost all cases, these side effects can be treated and aren’t life-threatening.

If you are taking PEP, talk to your health care provider if you have any side effect that bothers you or that does not go away.

PEP medicines may also interact with other medicines that a person is taking (called a drug interaction). For this reason, it’s important to tell your health care provider about any other medicines that you take, including over the counter medications, street drugs, and alcohol.

Can You Take PEP When You Are Pregnant or Breastfeeding?

Yes. PEP is safe during pregnancy and breastfeeding. If you are pregnant or breastfeeding, consult with a health care provider about PEP and which PEP regimen is right for you.

Can You Take PEP Every Time You Have a Potential Exposure to HIV?

No. PEP should be used only in emergency situations. It is not intended to replace regular use of other HIV prevention methods. If you feel that you might be exposed to HIV frequently, talk to your health care professional about PrEP (pre-exposure prophylaxis).

How Can You Pay for PEP?

In many states, PEP is covered by health insurance, including Medicaid.

If you do not have health insurance, or you need help paying for PEP co-payments, there are some programs that might help you with free or low-cost PEP medicines:

  • If you’re prescribed PEP and you don’t have insurance—Some pharmaceutical companies have patient assistance programs (PAPs) to help people who do not have insurance or whose insurance does not cover a specific medication to have access to the medications they need at no or low cost. Requests can be handled urgently in many cases to avoid a delay in getting PEP. The health care provider who prescribes PEP for you may be able to help you complete the forms. Find a list of these PAPs and read about how to access these programs (PDF, 178 KB).
  • If you’re prescribed PEP and you have insurance but need help covering the costs of co-payments—Some pharmaceutical companies have co-payment assistance programs (CAPs) to help people who have insurance to lower or eliminate the amount they owe as a deductible, co-insurance, and/or co-payment for a specific medication. The health care provider who prescribes PEP for you may be able to help you complete the forms. Find a list of these CAPs and read about how to access these programs (PDF, 178 KB).
  • If you’re prescribed PEP after a sexual assault—You may qualify for partial or total reimbursement for medicines 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’re a health care worker who was exposed to HIV on the job—Your workplace health insurance or workers’ compensation will usually pay for PEP.