PEP FAQs

Today, prescription medications provide an effective tool to prevent HIV. Patients at high risk for HIV may be able to take advantage of newer medicines prescribed by their healthcare providers for pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP).

PEP is the use of antiretroviral medication to prevent HIV infection in an HIV-negative person who has had a specific high-risk exposure to HIV. Such an exposure typically occurs through sex or sharing syringes (or other injection equipment) with someone who has or might have HIV. Exposure to HIV is a medical emergency, because HIV establishes infection very quickly, often within 24 to 36 hours after exposure. Health care providers should evaluate persons rapidly for PEP when care is sought within 72 hours after a potential exposure.

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What are the guidelines for prescribing PEP?

National Guidelines from the Centers for Disease Control (CDC) pdf icon[PDF – 1 MB] published in 2005 were updated in April of 2016. The update incorporates additional evidence about the use of PEP from animal studies and human observational studies, as well as consideration of new antiretroviral agents introduced after the publications of the last Guidelines. One key change from the 2005 recommendations is a new, more effective preferred drug regimen that has fewer side effects.

Which types of exposure warrant PEP?

PEP initiation should be considered in people whose vagina, rectum, eye, mouth or other mucuous membrane, non-intact skin, or perforated skin (eg, needle stick) come into contact with potentially contaminated body fluids from an HIV-infected source, as long as exposure has occurred within a 72-hour window. (If the source is of unknown HIV status, a case-by-case determination may be made.)

Who can prescribe PEP?

Any licensed prescriber can prescribe PEP. Emergency medicine physicians are among the most frequent prescribers of PEP, given the need for immediate treatment after exposure. Clinicians working in ambulatory care practices can also ensure that their non-HIV-infected patients who report risk behavior are aware of PEP, and know how to access it.

What is the recommended PEP regimen?

All persons offered PEP should be prescribed a 28-day course of a 3-drug antiretroviral regimen. Since adherence is critical for PEP efficacy, it is preferable to select regimens that minimize side effects, number of doses per day and the number of pills per dose.

The preferred PEP regimen for otherwise healthy adults and adolescents is tenofovir disoproxil fumarate (TDF) (300 mg) + emtricitibine (FTC) 200 mg) once daily PLUS raltegravir (RAL) (400 mg) twice daily or dolutegravir (DTG) (50 mg) once daily).

Is PEP safe?

The current preferred regimen is generally safe and well tolerated. Patients usually experience only mild side effects on the preferred PEP regimen. Most importantly, PEP is only taken for 28 days. In almost all cases, the benefits of HIV prevention outweigh any other risks posed by the medication. In a meta-analysis of 24 PEP-related studies, including 23 cohort studies and 1 randomized clinical trial, nausea, vomiting, diarrhea and fatigue were the most commonly reported side effects.

Who is not eligible for PEP?

  • PEP is only indicated for potentially exposed people without HIV infection.
  • PEP is unlikely to be effective in people who have been exposed more than 72 hours before seeking medical assistance.
  • PEP should be provided only for infrequent exposures. People who engage in behaviors that result in frequent, recurrent exposures to HIV should be considered for intensive sexual or injection risk-reduction interventions and pre-exposure prophylaxis (PrEP) with daily oral doses of combination TDF+FTC (Truvada®). However if the most recent recurring exposure is within the 72-hour window prior to an evaluation, PEP may be indicated with transition of the patient to PrEP after completion of 28 days of PEP medication.

What baseline assessment is required for individuals beginning PEP?

Guidelines recommend the following baseline screening before initiating PEP:

  • HIV rapid test at baseline. If baseline rapid test indicates existing HIV infection, PEP should not be started. However, if rapid HIV baseline test is not available, there should be no delay in starting PEP. Oral HIV tests are not recommended for use among persons being evaluated for PEP.
  • Pregnancy test (if a woman is of reproductive age, not using highly effective contraception, eg IUDs or other long-active reversible contraceptives (LARCs), oral contraceptives, or properly used condoms, and with vaginal exposure to semen).
  • Serum liver enzymes
  • BUN/creatinine
  • STI screening
    • Persons being evaluated for PEP because of a sexual encounter should have STI-specific nucleic acid amplification (NAAT testing) for chlamydia and gonorrhea, and a blood test for syphilis
  • Hepatitis B testing, including hepatitis B surface antigen, surface antibody, and core antibody
  • Hepatitis C (HCV) antibody

Note: The first dose of PEP should always be expedited; testing can wait until after PEP has been initiated.

What additional support is required for patients on PEP?

Providers should maintain contact with their patients on PEP, either by telephone or in a clinic visit for the entire duration of PEP. This is both to ensure adherence and to facilitate follow-up HIV testing at 30 and 90 days to determine if HIV infection has occurred. Additionally, people whose sexual or injection-related exposures result in concurrent acquisition of HCV and HIV infection might have delayed HIV seroconversion.

Will PEP be covered by my patients’ health insurance?

In many states, PEP is covered by insurance, including Medicaid. If the patient is not covered under insurance, there are assistance programs run by various manufacturers.