When should Human Immunodeficiency Virus (HIV) post-exposure prophylaxis (PEP) be initiated?

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Last updated: February 12, 2025View editorial policy

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From the Guidelines

HIV post-exposure prophylaxis (PEP) should be initiated as soon as possible, ideally within 72 hours of exposure.

Key Considerations

  • The decision to initiate PEP should be based on the potential risk of HIV transmission, considering factors such as the type of exposure, the HIV status of the source, and local epidemiological patterns 1.
  • PEP is recommended for individuals with exposures that pose a substantial risk for HIV transmission, including bodily fluid exposures, mucous membrane exposures, and parenteral exposures 1.
  • The choice of antiretroviral regimen for PEP should be based on the risk assessment of the exposure and the potential background drug resistance at the population level, with a basic two-drug regimen recommended for most exposures and an expanded three-drug regimen considered for exposures that pose an increased risk for transmission 1.

Eligibility Assessment

  • Eligibility assessment should consider the HIV status of the source, whenever possible, as well as background prevalence and local epidemiological patterns 1.
  • Exposures that do not require PEP include those where the exposed individual is already HIV positive, the source is established to be HIV negative, or the exposure does not pose a significant risk for transmission 1.

Timing of Initiation

  • While the ideal time for initiating PEP is within 72 hours of exposure, providers should consider the range of other essential interventions and referrals that should be offered to clients presenting after this timeframe 1.
  • In some cases, PEP may still be beneficial when initiated more than 72 hours after exposure, particularly if the exposure poses a serious risk for transmission 1.

From the Research

Initiation of HIV Post-Exposure Prophylaxis (PEP)

  • HIV PEP should be initiated as soon as possible, preferably within 36-72 hours of exposure to HIV 2, 3.
  • The timing and duration of PEP are crucial, with data showing that PEP is most effective when initiated within 72 hours of exposure and continued for four weeks 3.
  • Current guidelines recommend a 28-day course of antiretroviral therapy (ART) after exposure to HIV 2.

Special Considerations

  • For nonoccupational exposures, such as sexual exposure, a three-drug PEP regimen is advised 3.
  • For sexual assault survivors, three-drug PEP should be given regardless of assailant characteristics 3.
  • In complicated situations, such as exposure of a pregnant woman or when a source is known to be infected with HIV, expert consultation is advised 3.

Assessment and Monitoring

  • Patients presenting for care after HIV exposure should have baseline testing for HIV antibodies, and follow-up HIV antibody testing at four to six weeks, three months, and six months after exposure 3.
  • Early monitoring of tolerance and adherence to the treatment, as well as subsequent monitoring of people exposed, is essential 4.
  • Psychological support is also necessary for individuals who have been exposed to HIV 4.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Current perspectives in HIV post-exposure prophylaxis.

HIV/AIDS (Auckland, N.Z.), 2014

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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