What Is PEP for HIV?

Post-exposure prophylaxis (PEP) is a short course of antiretroviral drugs that is commonly taken very soon after engaging in a high-risk event or after involuntary exposure to human immunodeficiency virus (HIV). PEP stops HIV seroconversion—the period during which the body starts producing detectable levels of HIV antibodies—by killing the infected cells. Simply put, if taken right away, these drugs can prevent HIV from taking hold of your immune system, which, if left untreated, could lead to the disease AIDS. In order for PEP to be effective, it must be started within 72 hours of possible exposure.

man sitting on bed with PEP

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What Is PEP?

PEP is a way to help prevent the transmission of HIV in an HIV-negative person who may have been recently exposed to the virus. PEP consists of taking three HIV antiviral drugs for 28 days after exposure to the virus. These drugs include:

  • Tenofovir
  • Emtricitabine
  • Raltegravir or dolutegravir

Ideally, the medication should be started immediately, within one–two hours of exposure.

A PEP supply of three–five days is usually first given for emergency use, followed by the rest of the 28-day dose. PEP should not be confused with PrEP, which involves taking two HIV medications on an ongoing basis, before, during, and after possible exposure to HIV.

Who Should Use It?

PEP should be used by anyone who has had a very recent single exposure to the HIV virus. The most common high-risk situations are within the occupational context, such as an inadvertent needlestick at the hospital, or the nonoccupational context, such as sexual exposure or injection drug use.

PEP is only intended for emergencies and should not be used if you are regularly exposed to HIV.

Other groups that may need PEP are:

  • Those who have been sexually assaulted
  • Those who are unclear if a sexual partner has or had been exposed to HIV
  • Anyone who engages in needle sharing 

Of note, if you are pregnant and have been exposed to HIV, your doctor will prescribe PEP with raltegravir instead of dolutegravir to limit the risk of birth defects.

When to Call Your Doctor

PEP is highly effective. If side effects last for more than two weeks, contact a healthcare professional.

Possible side effects from PEP include:

  • Fatigue
  • Diarrhea
  • Nausea
  • Abdominal cramps
  • Bloating
  • Headache
  • Vivid dreams
  • Insomnia
  • Depression
  • Increased thirst
  • Vomiting

Talk to a healthcare provider if you develop a fever or rash during or after PEP use, as this may be a sign that the medication has not worked and you are experiencing the first symptoms of acute HIV infection.

PEP is not 100% effective, so there are times when the drug will not prevent you from acquiring the virus.

The following symptoms may signal the acute phase of HIV infection:

  • Fever
  • Chills
  • Rash
  • Night sweats
  • Muscle aches
  • Sore throat
  • Fatigue
  • Swollen lymph nodes
  • Mouth ulcers

If you experience any of these symptoms while on PEP, contact a healthcare professional immediately. 

How Do You Take PEP?

PEP consists of three drugs that you take one–two times per day for 28 days. Ideally, the first dose of PEP should be administered immediately, within two hours but no later than 72 hours after an exposure, because the effectiveness of PEP decreases over time.

It is important to take all the doses—at the right time and in the right way—to give PEP the best chance of working.

Although PEP does not prevent 100% of HIV infections, it has been shown to decrease the transmission of HIV by more than 80%.

Paying for PEP

PEP is covered by most, if not all, insurance plans. If you were exposed to HIV while on the job, workers' compensation may cover your drug medication treatment. No matter your method of exposure, PEP should be covered and will be administered to you by your doctor or another healthcare professional. 

If you do not have insurance, you may be able to take advantage of a drug company's patient assistance program to help with payment.

Follow-up Tests

If you are on PEP, a healthcare professional will ask you to schedule a follow-up appointment within 72 hours. Your appointment will include:

  • HIV testing
  • Lab monitoring for drug toxicity
  • Counseling

Repeat HIV testing will be obtained 30 days and 90 days after exposure. Testing should be performed using a fourth-generation HIV test. If a fourth-generation test is unavailable, an older test may be used along with more frequent follow-up appointments to limit the possibility of a false-negative result.

Repeat HIV testing should be obtained at six weeks, 12 weeks, and six months minimum. Sometimes these repeat tests are in addition to testing at 30 days and 90 days.

If you test positive or develop symptoms of acute retroviral syndrome, an HIV viral load may be obtained.

A Word From Verywell

Although HIV rates have dropped substantially in the past decade, HIV transmission still remains a concern. In order to help prevent contracting the virus, it's important to use condoms, avoid unsafe sexual practices, take precautions when working around body fluid samples, and avoid the use of unsterile equipment—including needles.

PEP should not be used as a regular means of preventing the transmission of HIV, and it does not prevent the spread of other sexually transmitted infections (STIs). Condoms, when used properly, are the most effective way of preventing HIV and most other STIs.

Having a candid conversation about condom use and STI testing is not only helpful in preventing STIs but is often integral to a happy and healthy sex life. If you or a loved one suspects that you have come into contact with someone who is HIV positive, seek immediate medical attention.

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  1. Centers for Disease Control and Prevention. Post-exposure prophylaxis (PEP). Updated October 15, 2020.

  2. HIV Prophylaxis Following Occupational Exposure. New York Department of Health AIDS Institute. 2019. Available at: http://www.hivguidelines.org 

  3. Hoenigl M, Green N, Camacho M, et al. Signs or symptoms of acute hiv infection in a cohort undergoing community-based screening - volume 22, number 3—march 2016 - emerging infectious diseases journal - cdc. doi:10.3201/eid2203.151607

  4. DeHaan E. Post-exposure prophylaxis (PEP) to prevent HIV infection. Baltimore (MD): Johns Hopkins University; 2020 Jun.