What is post-exposure prophylaxis PEP and when used?

Post-Exposure Prophylaxis (PEP) is a short-term emergency medical treatment used to prevent infection after potential exposure to a pathogen, most commonly the Human Immunodeficiency Virus (HIV).

PEP stands for Post-Exposure Prophylaxis, where “prophylaxis” means disease prevention. It involves taking a 28-day course of antiretroviral (ARV) medication soon after possible exposure to HIV in order to stop the virus from establishing an infection.

When PEP Is Used

PEP is recommended in emergency situations, not for routine prevention. It must be started within 72 hours (preferably within 24 hours) after potential exposure. Typical scenarios include:

1. Sexual exposure
   • Condom breakage or condomless sex with an HIV-positive or status-unknown partner.
   • Sexual assault cases.
2. Blood exposure
   • Needlestick injuries or contact with infected blood or body fluids (e.g., in healthcare settings).
3. Injection drug use
   • Sharing syringes, needles, or injection equipment with an HIV-positive individual.
4. Other mucosal exposure
   • Contact of blood or bodily fluids with the eyes, mouth, or open wounds.

Duration and Treatment

• The standard PEP regimen consists of three ARV drugs taken daily for 28 days.
• It should be initiated as soon as possible, because HIV can begin to establish infection within 24–36 hours after exposure.
• The regimen’s success depends on strict adherence—missing doses can reduce protection significantly.

Effectiveness and Follow-Up

• PEP is highly effective if started promptly and taken consistently, but it is not 100% protective.
• HIV testing is done before starting and again after completion (typically at 6 weeks, 3 months, and 6 months) to confirm that infection was prevented.
• PEP is not a substitute for pre-exposure prophylaxis (PrEP), which is taken daily or by injection before exposure for ongoing prevention.