Post-exposure HIV prophylaxis

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Evidence last reviewed: 14 Apr 2026

Topic last updated: 06 May 2026

Post-exposure HIV prophylaxis must be initiated as soon as possible, ideally within 24 hours, and preferably within 72 hours of exposure.

Timely access to post-exposure prophylaxis (PEP) is the most crucial factor in PEP effectiveness. The duration of PEP is 28 days.

Most exposures have only a low risk of HIV transmission even in the absence of PEP.

PEP reduces the likelihood of HIV seroconversion by approximately 80%.

PEP regimens are associated with a low risk of toxicity.

Exposure to HIV is considered a medical emergency.

Definition

PEP is the administration of antiretroviral drugs to people without HIV who may have been exposed to HIV through occupational or nonoccupational (e.g., sexual, needle, or other) exposure in order to prevent HIV acquisition.[1] Once exposed to HIV, there may be a brief period before the infection is established, during which antiretroviral drugs may successfully prevent viral replication.[2][3] PEP should be given as soon as possible following exposure, ideally within 24 hours, but no later than 72 hours after exposure. A 28-day course is recommended.[1][4][5]

This topic focuses on PEP. For pre-exposure prophylaxis (PrEP), see HIV in adults. See Overview of HIV for other available HIV topics.

Anamnesis y examen

Principales factores de diagnóstico

exposure to HIV within past 72 hours
breakage, slippage, or nonusage of a condom
history of ejaculation from source
trauma or skin break
genital ulcers
source from high-risk group for HIV viremia
source from geographic area with high HIV prevalence
high-risk sexual history in exposed person
detectable HIV viral load in source

Todos los datos

Otros factores de diagnóstico

history of negative HIV test in source
source with hepatitis coinfection
antiviral HIV resistance in source
current prescription or nonprescription drugs
history of drug allergies
flu-like illness

Todos los datos

Factores de riesgo

blood transfusion from donor living with HIV
receptive anal intercourse
injection drug use and needle sharing
percutaneous (needlestick) injury
insertive anal intercourse
receptive penile-vaginal intercourse
insertive penile-vaginal intercourse
insertive or receptive oral intercourse

Todos los datos

Pruebas diagnósticas

Primeras pruebas diagnósticas para solicitar

fourth-generation HIV antigen/antibody enzyme-linked immunosorbent assay (ELISA)
HIV nucleic acid test
renal function tests
liver function tests
hepatitis B serology
hepatitis C serology
pregnancy test
screening for other sexually transmitted infections (STIs)

Todos los datos

Pruebas diagnósticas que deben considerarse

HIV viral load (if symptoms of HIV seroconversion)

Todos los datos

Algoritmo de tratamiento

Agudo

adults or adolescents ≥12 years: nonpregnant

pregnant or breastfeeding

children

Colaboradores

Autores

Julie Fox, BSc(Hons), MBChB, MRCP, MD

HIV consultant and Honorary Senior Lecturer KCL

Department of HIV

Harrison Wing

Guy’s and St Thomas Hospital NHS Foundation Trust

London

Disclosures

JF declares that she has no competing interests.

Acknowledgements

Dr Julie Fox would like to gratefully acknowledge Dr Ming Jie Lee, Dr Jennifer A. Johnson, Dr Paul Sax, Dr Rebecca Plank, Dr Michael Brady, Dr Emily Cheserem, and Dr Claire M. Naftalin, the previous contributors to this topic.

Disclosures

MJL has received consulting fees from Thriva Ltd. and conference reimbursement from Gilead Sciences, Inc., and travel grants from ViiV Healthcare, not related to this work. JAJ declares that she has no competing interests. PS serves as a consultant for Abbott, BMS, Gilead, GSK, Merck, and Janssen. He receives grant support from BMS, Gilead, and GSK. EC has been sponsored by GlaxoSmithKline for several conferences and sponsored by Gilead Sciences, Bristol-Myers Squibb Pharmaceuticals, and Abbott Laboratories to attend various educational programs. CMN has been sponsored by Bristol-Myers Squibb Pharmaceuticals to attend an educational program. CMN is an author of a reference cited in this topic. MB not disclosed. RP declares that she has no competing interests.

Peer reviewers

Professor Margaret Johnson, MB BS, MD, FRCP

Clinical Director

HIV/AIDS Services

Royal Free Hampstead NHS Trust

London

Disclosures

MJ declares that she has no competing interests.

William Rodriguez, MD

Chief Medical Officer

Foundation for Innovative New Diagnostics (FIND)

Campus Biotech

Geneva

Switzerland

Disclosures

Not disclosed.

Peer reviewer acknowledgements

BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.

Disclosures

Peer reviewer affiliations and disclosures pertain to the time of the review.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

World Health Organization. Guidelines for HIV post-exposure prophylaxis. Jul 2024 [internet publication].Full text

British Association for Sexual Health and HIV. Post-exposure prophylaxis. Sep 2021 [internet publication].Full text

Tanner MR, O'Shea JG, Byrd KM, et al. Antiretroviral postexposure prophylaxis after sexual, injection drug use, or other nonoccupational exposure to HIV - CDC recommendations, United States, 2025. May 2025 [internet publication].Full text Abstract

Kofman AD, Struble KA, Heneine W, et al. 2025 US Public Health Service guidelines for the management of occupational exposures to human immunodeficiency virus and recommendations for post-exposure prophylaxis in healthcare settings. Infect Control Hosp Epidemiol. 2025 Sep;46(9):863-73.Full text Abstract

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Guidelines
- Antiretroviral postexposure prophylaxis after sexual, injection drug use, or other nonoccupational exposure to HIV - CDC recommendations, United States, 2025
- Guidelines for HIV post-exposure prophylaxis
More Guidelines
Patient information
Hepatitis C: what is it?
HIV: prevention treatment (PrEP)
More Patient information
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Post-exposure HIV prophylaxis

Summary

Definition

Anamnesis y examen

Principales factores de diagnóstico

Otros factores de diagnóstico

Factores de riesgo

Pruebas diagnósticas

Primeras pruebas diagnósticas para solicitar

Pruebas diagnósticas que deben considerarse

Algoritmo de tratamiento

adults or adolescents ≥12 years: nonpregnant

pregnant or breastfeeding

children

Colaboradores

Autores

Julie Fox, BSc(Hons), MBChB, MRCP, MD

Disclosures

Acknowledgements

Disclosures

Peer reviewers

Professor Margaret Johnson, MB BS, MD, FRCP

Disclosures

William Rodriguez, MD

Disclosures

Peer reviewer acknowledgements

Disclosures

References

Key articles

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Guidelines

Patient information

Inicie sesión o suscríbase para acceder a todo el BMJ Best Practice

Inicie sesión o suscríbase para acceder a todo el BMJ Best Practice

Inicie sesión para acceder a todo el BMJ Best Practice