Retest for STDs in three situations: after a positive result, to make sure treatment worked (a test-of-cure); about three months after treatment to catch reinfection, which is common; and after a too-early negative, because most tests can't detect an infection until the window period has passed. Timing — not symptoms — drives accurate results.
| Item | Days after exposure |
|---|---|
| Chlamydia / gonorrhea (NAAT) | ~14 |
| HIV — NAT | 10–33 |
| HIV — antigen/antibody | 18–45 |
| HIV — rapid antibody | 23–90 |
Why retesting is a separate question from testing
A single negative result answers one question on one day. It doesn't tell you whether you tested early in the window, whether your treatment cleared the infection, or whether you picked it up again from an untreated partner. Those are three different problems, each with its own clock. Because many STIs cause no symptoms, you can't feel your way to an answer — screening, not how you feel, is what tells you your status. That's also why you can and should can you get an std test without symptoms? even when nothing feels wrong.
How the test works (sample and method)
Most STIs are tested from a simple sample. Chlamydia, gonorrhea, and trichomoniasis are detected with a NAAT (nucleic acid amplification test) run on a urine cup or a self-collected swab. HIV, syphilis, and hepatitis are tested from a blood draw. In practice it's minutes in the chair — pee in a cup or swab yourself in a private room, or hold out an arm for a quick draw — with results in a day or a few.
NAATs are the most sensitive method for chlamydia and gonorrhea, which is why they're recommended over older tests; modern NAATs are highly accurate, with specificity around 99% USPSTF. High specificity matters for retesting because it keeps false alarms rare when you're checking the same person more than once.
When to retest after exposure: the window period
There's a gap between exposure and when a test can detect an infection — the window period. Test inside that gap and you can get a falsely reassuring negative: the test isn't wrong, the infection just isn't detectable yet. That's the single most common reason for a false negative, and it's why a too-early negative should be repeated rather than trusted.
For chlamydia and gonorrhea, a NAAT is generally reliable about two weeks after exposure CDC. If you tested sooner because you were worried, retesting later is reasonable whenever a recent exposure is possible. For HIV, the window depends on which test you take:
- A nucleic acid test (NAT) can detect HIV about 10–33 days after exposure CDC, HIV Testing.
- An antigen/antibody lab test detects it about 18–45 days after exposure.
- A rapid antibody test detects it about 23–90 days after exposure.
The practical takeaway: a negative test early after a known exposure isn't a clean bill of health. For the full breakdown by infection, see when to test after exposure.
The three reasons to retest, explained
Window-period retest
This is for the early tester. If you got a negative before the window closed, you repeat the test once enough time has passed for the infection to become detectable. You're not doubting the lab — you're giving the infection time to show up. This applies to anyone who tested within days of a specific exposure.
Test-of-cure
A test-of-cure confirms that treatment cleared an infection. It isn't routine for every STI — for some, a properly treated infection is presumed cured and a too-soon retest can stay positive on leftover genetic material that's no longer a live infection. It's recommended in specific situations, such as pregnancy or persistent symptoms. Follow the guidance your clinician gives for your specific diagnosis rather than retesting on your own timeline.
Reinfection retest (the three-month check)
This is the one people skip, and it matters most. A successfully treated chlamydia or gonorrhea infection can come right back if a partner wasn't treated — so guidelines recommend a repeat test a few months after treatment to catch reinfection, not treatment failure. We cover the reasoning and timing in depth under chlamydia reinfection.
Where to get tested and what it costs
Testing is available at doctors' offices, health departments, Planned Parenthood, and Title X family-planning clinics — often free or low-cost — and at-home and self-collection kits exist for people who'd rather not go in person. You're rarely far from affordable care: the US has roughly 16,000 federally-funded community health centers and about 4,200 Title X family-planning clinics, plus tens of thousands of other public STI clinics, most offering free or income-based sliding-scale care HRSA.
At-home kits are convenient for a retest, but the same window rule applies — mind the timing so you collect your sample at the right moment, not too early. If you're weighing options, you can compare testing providers or just get tested through a local clinic.
Reading your results and how accurate they are
Most chlamydia and gonorrhea NAAT results come back as a clean positive or negative, and with specificity near 99% a positive is rarely a fluke. HIV and syphilis work differently. To guard against false positives, both use a two-step process — an initial screening test, then a different confirmatory test — and the result isn't final until the confirmatory step agrees.
A reactive rapid HIV test is a preliminary result, not a diagnosis; it has to be confirmed with a follow-up lab test before it counts CDC, 2024. The table below summarizes how to read each kind of result.
| Infection | Method | How a result is confirmed |
|---|---|---|
| Chlamydia / gonorrhea | NAAT (urine or swab) | Single highly specific test; positive is treated as a diagnosis |
| HIV | Blood (NAT, antigen/antibody, or rapid antibody) | Reactive screen must be confirmed by a different lab test |
| Syphilis | Blood | Two-step algorithm; not final until the confirmatory test agrees |
If a result is positive
Most curable STIs are cleared with a short course of antibiotics, and your partners need treatment too or you'll just pass it back and forth. For the specifics on regimens and what treatment is like, head to get tested and your clinician's prescribed plan — then mark your calendar for the reinfection retest.
When to see a clinician
See a clinician if you have a known exposure to a diagnosed partner, ongoing symptoms after treatment, a reactive HIV or syphilis screen awaiting confirmation, or a positive result during pregnancy. A clinician also helps you set the right retest date — early enough to catch reinfection, late enough to clear the window — so you're not testing into a falsely reassuring negative.