When should HIV post-exposure prophylaxis be initiated for effectiveness?

HIV post-exposure prophylaxis (PEP) should be initiated within hours after exposure to be most effective. The recommendation is to begin treatment as soon as possible, ideally within 72 hours following potential HIV exposure. The sooner PEP is started, the higher the chances of preventing the virus from establishing an infection.

Initiating treatment later than this timeframe significantly reduces its effectiveness. While it is important to act quickly, starting PEP immediately ensures that the medications can act on the virus before it has the opportunity to replicate and establish an infection. This is why timing is critical, and post-exposure prophylaxis is designed to be a time-sensitive intervention.