STD window periods — the time after a possible exposure before a test reliably detects the infection — vary substantially by infection and by the type of test used. Testing inside the window period can produce a false negative, so picking the right time matters.
HIV-1/2 antigen-antibody tests (sometimes called 4th-generation HIV tests) detect both the p24 antigen and antibodies, making them reliable about 18 to 45 days after exposure. Older antibody-only tests take longer (3 to 12 weeks). Chlamydia and gonorrhea urine PCR tests work within 1 to 2 weeks after exposure — among the shortest windows of any STI screen.
Syphilis is screened with the RPR antibody test, which is typically reliable 3 to 6 weeks after exposure. Herpes I and II IgG antibody tests take longer because herpes antibodies build slowly — 6 to 12 weeks is the conservative window. Hepatitis B and hepatitis C are detectable 6 to 9 weeks after exposure, with the highest-sensitivity testing at 12 weeks.
If you are uncertain when to test, call us at 571-500-7030. Our staff can help you pick the right test for your exposure timeline. In some cases, two-stage testing — an early screen followed by a confirmation at the window-period mark — gives the most peace of mind.
Key takeaways
- HIV antigen-antibody: 18–45 days
- Chlamydia & gonorrhea: 1–2 weeks
- Syphilis RPR: 3–6 weeks
- Herpes I & II IgG: 6–12 weeks
- Hepatitis B & C: 6–9 weeks