Direct answer: Bacterial infections like chlamydia, gonorrhea, and trichomoniasis are typically reliably testable within 7–14 days of exposure using a NAAT test. Syphilis needs about 21–42 days. HIV needs 18–45 days with a 4th-generation test or up to 90 days with an older antibody-only test. Hepatitis B needs 30–60 days and Hepatitis C can take up to 84 days. Use the window period calculator to check your specific exposure date against all nine at once.
Window periods, infection by infection
| Infection | Minimum days | Reliable days | Test type |
|---|---|---|---|
| Chlamydia | 7 | 14 | NAAT urine/swab |
| Gonorrhea | 7 | 14 | NAAT urine/swab |
| Trichomoniasis | 5 | 14 | NAAT / wet mount |
| Syphilis | 21 | 42 | RPR / blood antibody |
| HIV (4th-gen) | 18 | 45 | Antigen/antibody blood test |
| HIV (antibody-only) | 23 | 90 | Antibody test |
| Hepatitis B | 30 | 60 | HBsAg blood test |
| Hepatitis C | 56 | 84 | HCV antibody blood test |
Figures reflect published CDC STI and HIV testing guidance. Individual results can vary by lab and test generation — use these as planning estimates, not guarantees.
Why the ranges exist instead of a single number
Each infection has a "minimum" day, where a test can sometimes detect it, and a "reliable" day, where detection is consistently accurate across the population. The gap between the two exists because individual immune responses vary — some people develop detectable antibodies faster than others. Testing at the minimum can catch an early infection, but a negative result that early is not conclusive the way it is once you've passed the reliable-day threshold.
The one exception: symptoms change the calculation
If you have symptoms — discharge, sores, pelvic pain, unusual rash — CDC guidance generally supports testing immediately regardless of the calendar, since a swab or culture from an active symptomatic site behaves differently than a routine screening test taken from an asymptomatic person. Waiting out a window period is a strategy for asymptomatic screening after a possible exposure, not for someone who already has symptoms.
What to do while you wait
Avoid unprotected sexual contact until you've tested and received results past the reliable window. If your exposure was within the last 72 hours and involved a risk of HIV, contact a healthcare provider immediately to ask about post-exposure prophylaxis (PEP), which is time-sensitive in a way testing is not.
Frequently Asked Questions
Which STD has the shortest testing window?
Trichomoniasis and bacterial infections like chlamydia and gonorrhea have the shortest reliable windows, typically becoming testable within 5–14 days using a NAAT test.
Which STD has the longest testing window?
Hepatitis C and antibody-only HIV tests have the longest windows, sometimes requiring up to 90 days for a fully reliable result.
Can I test at the minimum window instead of waiting for the reliable window?
You can, but a result at the minimum-detection point carries a higher chance of a false negative than one taken at the fully reliable point. If you test early and the result is negative, CDC guidance generally recommends a confirmatory retest once the reliable window has passed.
Note: This article is for general information only and is not medical advice. See our full disclaimer.