Most sexually active adults should screen for STIs at least once a year, and every 3 to 6 months if you have new or multiple partners, condomless sex, or share injection equipment. Test based on your risk and the window period, because many infections are silent and only a test reveals your status.
| Item | Days after exposure |
|---|---|
| Chlamydia / gonorrhea (NAAT) | ~14 |
| HIV — NAT | 10–33 |
| HIV — antigen/antibody | 18–45 |
| HIV — rapid antibody | 23–90 |
How often should you actually test? Match it to your risk
No single answer fits everyone. The frequency that protects you depends on who you sleep with, how, and how often. Annual screening is the baseline because many STIs cause no symptoms at all, so how you feel tells you almost nothing about whether you're infected. A test is the only way to catch a silent infection before it does quiet damage or passes to someone else.
Use these tiers to find your interval, then book it. You can
- Once a year (baseline): Every sexually active person benefits from at least an annual screen for the common STIs. The USPSTF recommends routine chlamydia and gonorrhea screening for sexually active women, including a yearly check for those who are younger or otherwise at higher risk USPSTF.
- Every 3 to 6 months: Step up to quarterly or twice-yearly testing if you have new partners, more than one partner, condomless sex, sex while using drugs or alcohol, or you're a man who has sex with men. People taking PrEP also test on this rhythm.
- At the start of every pregnancy: Standard prenatal care includes HIV, syphilis, and hepatitis screening, with repeat testing later in pregnancy for those at higher risk.
- After any new exposure: If you had condomless sex with a new or untested partner, or a partner tells you they tested positive, test once the window period has passed, regardless of when you last tested.
- One-time, at least once: CDC recommends everyone be tested for HIV at least once in their life as part of routine care CDC, HIV Testing.
How the test works: sample and method
The mechanics are quick and far less involved than most people imagine. What's collected depends on the infection, since each test looks for something different: bacterial DNA, viral genetic material, or antibodies your immune system made in response.
- Urine or a swab covers chlamydia, gonorrhea, and trichomoniasis. You pee in a cup or collect a vaginal, rectal, or throat swab yourself, and many clinics let you do the swab in a private bathroom. The lab runs a NAAT, which amplifies and detects the organism's genetic material.
- A blood draw covers HIV, syphilis, and hepatitis, since those are found through the blood by detecting antigens or antibodies.
In practice it's minutes in the chair: a urine cup or self-collected swab for most infections, a quick blood draw for the rest, then results back in a day or a few CDC. NAATs are the most sensitive tests available for chlamydia and gonorrhea, with specificity around 99%, which is why they're the recommended method. For a deeper walk-through of what each test involves, see our guide to how to.
When to test after exposure: the window period
The most common testing mistake is going in too soon. Every infection has a window period, the gap between exposure and when a test can actually detect it. Test inside that window and you can get a negative result that's falsely reassuring, because the infection is present but hasn't multiplied or triggered enough antibodies to register yet. The test isn't broken; the infection simply isn't detectable yet, so a too-early negative should be repeated.
| Infection / test | When it becomes detectable after exposure | Practical move |
|---|---|---|
| HIV — nucleic acid test (NAT) | About 10–33 days | Earliest detection; used after a high-risk exposure |
| HIV — antigen/antibody lab test | About 18–45 days | Standard lab screen |
| HIV — rapid antibody test | About 23–90 days | Fast, but retest later if very recent exposure |
| Chlamydia & gonorrhea (NAAT) | Generally reliable about 2 weeks | If you test sooner, retest later when exposure is recent |
If you tested before the window closed, treat that negative as provisional and repeat it. At-home and clinic kits both work fine, so long as you mind the timing and test at the right point. For exposure-by-exposure detail, our page on breaks down each timeline.
Where to get tested and what it costs
You're rarely far from affordable testing. Care is available at doctors' offices, health departments, Planned Parenthood, and Title X family-planning clinics, often free or on an income-based sliding scale, plus at-home and self-collection kits you order online.
The safety net is large. The US has roughly 16,000 federally funded community health centers and about 4,200 Title X family-planning clinics, on top of tens of thousands of other public STI clinics, most offering free or sliding-scale care HRSA. If cost is your worry, start with a community health center or health department rather than assuming you'll get a surprise bill. You can also if you'd rather collect a sample at home.
Reading your results and how accurate they are
A negative after the window has fully passed is reliable. A negative taken too early is the main cause of a false negative and should be repeated. False positives are rarer, and the testing system is built specifically to catch them.
For HIV and syphilis, results come from a two-step process: an initial screening test, then a different confirmatory test, and a result isn't final until the confirmatory step agrees. A reactive rapid HIV test is a preliminary result and must be confirmed with a follow-up lab test before it counts as a diagnosis, so don't panic on the first reactive line. Syphilis blood testing works the same layered way; our guide to the syphilis test explains how the treponemal and non-treponemal steps fit together CDC, 2024.
If a result is positive
A positive STI result is treatable, and most are cured with a short course of medication or well managed long-term. Don't wait; start treatment and notify recent partners. See our full guide to STD treatment for what each regimen involves and how to get it.
When to see a clinician
Book a visit rather than relying on a home kit when any of these are true:
- You have symptoms such as discharge, burning with urination, sores, pelvic or testicular pain, or unusual bleeding.
- A partner told you they tested positive, so you may need treatment and timed retesting.
- You're pregnant or planning to be, since screening and treatment protect the baby.
- You had a confirmed positive and need treatment plus a follow-up test to confirm the infection cleared.
- You're unsure which tests you need or when your window period closes.
After treatment for chlamydia or gonorrhea, a repeat test a few months later matters more than people expect, because reinfection from an untreated partner is common. See our page on chlamydia reinfection for the retest timing.