The standard test for chlamydia is a nucleic acid amplification test, commonly called a NAAT. It works by detecting the genetic material of the bacteria in a urine sample or swab, and it’s highly accurate: about 94% sensitive and 99% specific, meaning it catches nearly all infections and almost never flags one that isn’t there. The test is quick to take, painless, and results typically come back within one to five days.
How the Test Works
A NAAT amplifies tiny traces of chlamydia DNA or RNA in your sample so the lab can detect even a small number of bacteria. This makes it far more reliable than older culture-based methods, which required live bacteria to grow in a dish and missed infections more often. Today, NAATs are the gold standard at clinics, hospitals, and through mail-in home test kits.
What the Sample Collection Looks Like
For women, the preferred sample is a vaginal swab, which has higher sensitivity than a urine test for detecting chlamydia. You can collect this swab yourself in a bathroom at the clinic; a provider doesn’t need to do it for you. A pelvic exam is not required.
For men, the standard sample is a first-catch urine specimen, meaning the first part of your urine stream. You’ll typically be asked not to urinate for at least one hour before giving the sample so enough bacteria accumulates to be detected.
If you’ve had oral or anal sex, a urine test or vaginal swab won’t catch an infection in your throat or rectum. Those sites need their own swabs. Rectal and throat swabs are routinely recommended for men who have sex with men at every site of sexual contact, and can be considered for anyone based on their sexual history.
How Long to Wait After Exposure
Chlamydia doesn’t show up on a test immediately after exposure. The bacteria need time to multiply enough for the test to pick them up. Testing at one week after exposure will catch most infections. Waiting two weeks catches nearly all of them. If you test too early, you risk a false negative, meaning the infection is there but the test misses it.
Understanding Your Results
A positive result means chlamydia was detected. You’ll be prescribed antibiotics, and the infection typically clears within a week of treatment. Your sexual partners from the past 60 days should also be tested and treated.
A negative result means no chlamydia was found in your sample. If you tested within the window period (less than two weeks after a possible exposure), consider retesting.
Rarely, results come back equivocal or indeterminate. This happens when the initial test detects something but a confirmatory step doesn’t confirm it. Studies show the vast majority of equivocal results turn out to be negative on repeat testing, possibly due to sample contamination or a bacterial load too low to persist. You’ll typically be asked to come back for a repeat test rather than being treated automatically.
Retesting After Treatment
If you test positive and complete antibiotics, don’t rush to retest. The NAAT is so sensitive that it can pick up dead bacteria lingering after treatment, giving you a false positive. Retesting should wait at least four weeks after finishing antibiotics. For pregnant women, a retest at four weeks is specifically recommended to confirm the infection has cleared.
Whether or not you retest at four weeks, the CDC recommends everyone treated for chlamydia get tested again about three months later. This isn’t checking whether the antibiotics worked. It’s checking whether you’ve been reinfected, which is common, especially if a partner wasn’t treated at the same time.
At-Home Test Kits
Home testing kits use the same NAAT technology as clinic-based tests. You collect your own sample (a vaginal swab or urine, depending on the kit), mail it to a lab, and get results online or by phone. Experts consider self-collected samples to be as accurate as provider-collected ones. Home kits can be a practical option if you want privacy or don’t have easy access to a clinic, though they typically cost between $50 and $150 without insurance.
Who Should Get Tested Routinely
Chlamydia often causes no symptoms at all, which is why routine screening matters. The CDC recommends annual testing for:
- All sexually active women under 25
- Women 25 and older with risk factors like a new partner, multiple partners, a partner with other partners, inconsistent condom use, or a previous STI
- All pregnant women under 25, with repeat testing in the third trimester
- Men who have sex with men, at least annually at all sites of contact, and every three to six months if on PrEP, living with HIV, or if either partner has multiple partners
- People living with HIV, at their first evaluation and at least yearly after that
For heterosexual men at low risk, there isn’t enough evidence to recommend routine screening, though testing is reasonable in higher-prevalence settings like STI clinics or correctional facilities. Transgender and gender diverse individuals should be screened based on their anatomy and sexual practices: anyone with a cervix who is under 25 and sexually active qualifies for annual screening under the same guidelines as cisgender women.