Tools
STI Window-Period Calculator
Pick an exposure date; see when each STI test becomes meaningful and when a definitive-negative is reliable. Different infections have different windows.
Today is the default. Pick the date of the unprotected or higher-risk encounter.
PEP first if needed
If you're within 72 hours of a high-risk HIV exposure, go to an ER or sexual-health clinic now for post-exposure prophylaxis (PEP). Sooner is better; under 24 hours is best. PEP is a 28-day medication that prevents HIV infection if started in time. The window-period calculator below is for after PEP / for non-HIV testing.
Sources: BASHH UK National Guidelines on STI testing (2024); CDC STI testing recommendations 2024; UK Health Security Agency. Verify with a sexual-health clinic for individualised testing schedule.