Chlamydia is a common sexually transmitted infection (STI) caused by the bacterium Chlamydia trachomatis. It spreads through vaginal, anal or oral sex without a condom, and from a mother to her baby during childbirth. Most people never notice symptoms. When symptoms do appear, the usual chlamydia symptoms are an unusual discharge from the vagina or penis and a burning feeling when you pee.
The good news: chlamydia is easy to test for with a urine sample or a swab, and it is curable with antibiotics. The first-choice treatment in the United States is doxycycline for 7 days. Without treatment, chlamydia in women can spread to the uterus and fallopian tubes and cause pelvic inflammatory disease, infertility or an ectopic pregnancy.
Below: the signs in men and women, which test to ask for, treatment and retesting, partners, pregnancy, and what changed between 2023 and 2026.
Key takeaways
- Chlamydia often has no symptoms, so testing is the only way to know. Sexually active women 24 or younger should be screened yearly.
- The test is a NAAT (nucleic acid amplification test) on a urine sample or a vaginal, rectal or throat swab, which you can often collect yourself.
- Doxycycline 100 mg twice a day for 7 days is the recommended treatment. A single 1 g dose of azithromycin is an alternative and the usual choice in pregnancy.
- Avoid sex for 7 days after treatment and until your partners are treated, then get retested about 3 months later, because reinfection is common.
- Untreated chlamydia can silently damage fertility; antibiotics cannot undo scarring.
What is chlamydia?
Chlamydia is a bacterial infection of the lining (mucous membranes) of the cervix, urethra, rectum, throat or eyes. It is more common in young people, especially young women.
The World Health Organization estimates 128.5 million new chlamydia infections among adults aged 15 to 49 worldwide in 2020, with a prevalence of 4.0% in women and 2.5% in men. In the United States, the CDC counted 1,515,985 reported cases in 2024 (943,890 in women and 564,489 in men), a rate of 445.7 per 100,000 people. That is 8% fewer than in 2023, but many silent infections are never diagnosed.
Strains matter. Serovars A to K cause mild or silent infections (serovar D in the genitals, serovar B in trachoma, an eye disease of young children). Serovars L1 to L3 cause lymphogranuloma venereum (LGV), a more invasive form.
Worried about a rash? Our article on chlamydia rash and its real causes explains which skin signs can be linked to it.
How chlamydia spreads and who is at risk
How does chlamydia start? The bacteria pass from one person to another during vaginal, anal or oral sex without a condom with someone who has the infection. A pregnant woman can pass chlamydia to her baby during delivery.
Anyone who is sexually active can get chlamydia. The risk is higher if you:
- are 24 or younger, the age group with the highest prevalence;
- have a new sex partner, more than one partner, or a partner who has other partners;
- have a partner who has an STI, or have had chlamydia or another STI before;
- do not use condoms consistently;
- are a man who has sex with men.
Having chlamydia once does not protect you: you can catch it again.
Chlamydia symptoms and warning signs
Chlamydia is often called a silent infection. Cleveland Clinic estimates that 50% to 70% of people with chlamydia never notice symptoms, and more than 85% of men with rectal chlamydia had no symptoms in a large Australian trial. Symptoms, if any, may start up to three weeks after sex, sometimes later.
What are 5 signs of chlamydia? The most common ones, in men and women together, are:
- a new or unusual discharge from the vagina or penis;
- burning or pain when you urinate;
- bleeding between periods or after sex (in women);
- pain or swelling in one or both testicles (in men, less common);
- rectal pain, discharge or bleeding after anal sex or by spread from the vagina.
Burning when you pee is easily mistaken for a bladder infection. If a urinalysis showed white blood cells, our guide to leukocytes in urine explains the possible causes.
Chlamydia in women
Chlamydia symptoms in women are often mild or absent: abnormal vaginal discharge (sometimes with a strong smell), burning when urinating, itching, bleeding between periods or after sex, lower belly discomfort. Pelvic pain, pain during sex, nausea and fever suggest spread to the uterus and tubes. Other causes are covered in our article on vaginal burning: causes and tests.
Chlamydia in men
Chlamydia in men, when it shows, causes discharge from the penis and burning when peeing (urethritis). Less often it reaches the epididymis behind the testicle, causing pain, swelling and sometimes fever. Other germs cause urethritis too, including gonorrhea and Ureaplasma, so a lab test is needed.
Rectal, throat and eye infections
Rectal chlamydia comes from anal sex or spread from the vagina: it is found in 33% to 83% of women with genital chlamydia, whatever their practices (CDC). Throat infection rarely causes symptoms. Chlamydia can also inflame the eyes, and newborns can develop eye infections; our guide to conjunctivitis (pink eye) covers the other causes.
Testing for chlamydia: NAAT, urine and swabs
The recommended test is a NAAT, which detects the bacteria's genetic material. It can be run on:
- a vaginal swab, the best sample for women, which you can collect yourself;
- first-catch urine (the first part of the stream), the best sample for men;
- a cervical swab or the liquid from a Pap test, which some NAATs accept;
- a rectal or throat swab if you have anal or oral sex: a genital test misses those sites.
Self-collection works. In a meta-analysis of 21 studies, self-taken vaginal swabs had 92% sensitivity and 98% specificity against clinician cervical swabs, and the CDC considers them equivalent.
If you test positive, the CDC advises tests for HIV, gonorrhea and syphilis too. Our article on STI serology panels explains which infections need a blood test rather than a swab.
Who should be screened, and how often
Screening people without symptoms prevents complications. US recommendations (USPSTF 2021, CDC 2021):
| Who | Recommendation | Usual sample |
|---|---|---|
| Sexually active women 24 or younger | Every year (USPSTF grade B) | Vaginal swab, often self-collected |
| Women 25 or older at increased risk | Every year: new or several partners, partner with other partners or with an STI | Vaginal swab or first-catch urine |
| Pregnant women under 25 or at risk | First prenatal visit and again in the third trimester | Vaginal swab or urine |
| Men who have sex with men | At least yearly at every site of contact; every 3 to 6 months if at higher risk (on PrEP, living with HIV) | Urine plus rectal swab (and throat if tested for gonorrhea) |
| Heterosexual men | No routine screening (USPSTF: insufficient evidence); consider in high-prevalence clinics | First-catch urine |
| Anyone with symptoms or a partner with an STI | Test now, whatever the date of the last test | Depends on symptoms and exposure sites |
How to read your chlamydia test result
A chlamydia NAAT gives no level or range: it reads detected (positive) or not detected (negative).
| Result or situation | What it usually means | Next step |
|---|---|---|
| C. trachomatis detected | Active infection at the sampled site | Treatment, partner notification, tests for HIV, gonorrhea and syphilis |
| Not detected | No infection found at that site | Retest if symptoms persist, after a new exposure, or at the next screening date |
| Negative genital test, but anal or oral sex | Rectal or throat infection not tested | Ask for a swab of each site of contact |
| Positive less than 4 weeks after treatment | Often leftover dead bacterial DNA (false positive) | Do not retest before 4 weeks unless your clinician advises it |
| Positive again about 3 months later | Usually reinfection, not treatment failure | Treat again and make sure every partner is treated |
| Positive, with pelvic pain or fever | Possible pelvic inflammatory disease | Same-day medical review |
A normal urinalysis does not rule out chlamydia. If you were treated for a urinary tract infection and symptoms continue, ask whether a chlamydia NAAT was done.
Chlamydia treatment: doxycycline and azithromycin
Chlamydia is curable. CDC 2021 regimens:
| Situation | Recommended | Alternatives |
|---|---|---|
| Adults and adolescents (not pregnant) | Doxycycline 100 mg by mouth twice a day for 7 days | Azithromycin 1 g once, or levofloxacin 500 mg once a day for 7 days |
| Pregnancy | Azithromycin 1 g once | Amoxicillin 500 mg three times a day for 7 days |
| Lymphogranuloma venereum (LGV) | Doxycycline 100 mg twice a day for 21 days | Azithromycin 1 g once a week for 3 weeks |
Why doxycycline first? Doxycycline is a tetracycline antibiotic; azithromycin blocks the bacterial ribosome; levofloxacin inhibits DNA gyrase (ChEMBL). A week of doxycycline works better for rectal infection: cure in 100% versus 74% with azithromycin in a US trial, 96.9% versus 76.4% in an Australian one. Since rectal infection is common in women with genital chlamydia, the CDC prefers doxycycline for everyone outside pregnancy.
A once-daily 200 mg delayed-release doxycycline works as well, with fewer stomach effects, but costs more. Take every dose and never share it. Azithromycin suits people who cannot manage a week of pills.
Sex, partners and expedited partner therapy
No sex for 7 days after a single dose, or until the 7-day course is finished and symptoms are gone, and until all partners are treated.
Partners from the 60 days before symptoms or diagnosis (and the most recent one) should be tested and treated. Where state law allows, expedited partner therapy (EPT) lets your clinician give you the medicine or a prescription for your partner. In a randomized trial, EPT lowered persistent or recurrent gonorrhea or chlamydia from 13% to 10%.
Retesting after treatment
How long does chlamydia take to go away? Usually a week or two with treatment, but the test can stay positive for 4 weeks from leftover DNA, so a test of cure is not needed outside pregnancy. Everyone should retest about 3 months later: a review found a median 13.9% of women reinfected, peaking at 19% to 20% at 8 to 10 months.
Complications of untreated chlamydia
Complications come from infection that goes undetected or keeps coming back.
- Pelvic inflammatory disease (PID): in high-risk settings, 2% to 5% of untreated women developed PID within about two weeks of a positive test.
- Infertility and ectopic pregnancy: after symptomatic PID, up to 18% of women may develop infertility, and scarred tubes raise the risk of a pregnancy outside the womb. Our guide to the fertility blood test covers other checks.
- Chronic pelvic pain: long-lasting lower belly pain can follow PID.
- Epididymitis in men, rarely leading to infertility.
- Reactive arthritis, with swollen joints and sometimes eye inflammation. See our overview of arthritis types and causes.
- HIV: untreated chlamydia may increase the chance of getting or passing on HIV. Our article on HIV and AIDS explains testing and PrEP.
Lymphogranuloma venereum (LGV)
LGV, caused by strains L1 to L3, invades deeper tissue. It can cause a genital ulcer, enlarged lymph nodes or, most often, proctocolitis: rectal pain, discharge, bleeding, constipation or fever that can mimic inflammatory bowel disease. The WHO reports a resurgence among gay and bisexual men. It needs 21 days of doxycycline.
Prevention: condoms, testing and doxy-PEP
Only abstinence avoids STIs completely. Otherwise, these steps lower the risk:
- use condoms correctly every time you have sex;
- a mutually monogamous relationship with a tested, uninfected partner;
- screening at the intervals above, partner treatment, and a retest 3 months after any infection;
- doxy-PEP for men who have sex with men and transgender women with an STI in the past year (see below).
Gonorrhea is checked on the same sample; our article on drug-resistant gonorrhea testing explains its treatment. Syphilis needs a blood test: see our guide to syphilis symptoms, stages and blood tests.
Chlamydia in pregnancy and in newborns
Chlamydia in pregnancy is linked to preterm birth and low birth weight, and the baby can be infected at delivery. Women under 25 or at risk are tested at the first prenatal visit and in the third trimester. Our article on blood tests during pregnancy lists other checks.
Azithromycin 1 g once is recommended (amoxicillin is the alternative); doxycycline is avoided in the second and third trimesters because it can discolor teeth. A test of cure about 4 weeks after treatment and a retest at 3 months are advised.
Newborns can develop eye infection 5 to 12 days after birth or pneumonia without fever at 1 to 3 months. The eye ointment given at birth does not prevent it: prenatal testing is the real protection.
When to see a doctor
Get tested by a doctor or sexual health clinic if you:
- notice discharge, burning when you pee, bleeding after sex or between periods, or rectal pain;
- have a partner with an STI, a new partner, or are due for screening;
- are pregnant or planning a pregnancy;
- still have symptoms after finishing treatment.
Seek same-day care for pelvic pain with fever or a painful, swollen testicle. Call 911 for severe abdominal pain or fainting, especially if you could be pregnant: an ectopic pregnancy can be life-threatening.
Latest scientific advances in chlamydia
Doxycycline after sex (doxy-PEP) is now a CDC recommendation
In the DoxyPEP trial (NEJM 2023, 501 men who have sex with men and transgender women), 200 mg of doxycycline within 72 hours after condomless sex cut gonorrhea, chlamydia and syphilis by two thirds (chlamydia relative risk 0.12 on HIV PrEP). In June 2024 the CDC recommended offering it to this group after a bacterial STI in the past 12 months, never more than 200 mg per 24 hours. A 2026 meta-analysis of three trials (1,278 people) found a 78% drop in chlamydia.
Doxy-PEP did not protect women in the first trial
In the only trial in cisgender women (449 young women in Kenya), STIs did not fall significantly (relative risk 0.88); hair tests found doxycycline in only 29% of samples, pointing to low adherence. A 2026 review of antibiotic resistance found mixed, low-quality evidence, so long-term effects remain under watch.
Doxycycline beats azithromycin for rectal infection
Two 2021 randomized trials and a meta-analysis of 2,457 patients showed higher cure rates for rectal chlamydia with 7 days of doxycycline than with one dose of azithromycin. For you: a week of tablets, but a better chance of lasting cure.
Testing at home, with results in 30 minutes
In March 2025 the FDA authorized the first over-the-counter test for chlamydia, gonorrhea and trichomoniasis run entirely at home (Visby Medical Women's Sexual Health Test). From a self-collected vaginal swab, it gives results in about 30 minutes and correctly identified 97.2% of positive and 98.8% of negative chlamydia samples. A positive result still needs a clinician.
Chlamydia vaccines enter human trials
There is no vaccine yet. The lead candidate, CTH522, was safe and produced antibodies in all vaccinated volunteers in two phase 1 trials (NCT02787109, and CHLM-02, NCT03926728, published 2024). A Sanofi mRNA vaccine is in a phase 1 trial in 80 adults (NCT06891417), due to finish in late 2027.
Which tests can help?
Tests often ordered together:
- chlamydia and gonorrhea NAAT on urine or swabs from each site of contact;
- an HIV test: see our guide to HIV blood test results;
- a syphilis blood test, such as the RPR and a treponemal test;
- a retest about 3 months after treatment (plus a test of cure at 4 weeks in pregnancy).
Keep your reports and the dates of treatment and retest.
Glossary
- NAAT: nucleic acid amplification test, which detects bacterial genetic material.
- First-catch urine: the first part of the urine stream.
- Pelvic inflammatory disease (PID): infection of the uterus, fallopian tubes or ovaries, often caused by chlamydia or gonorrhea.
- Ectopic pregnancy: a pregnancy outside the womb.
- Epididymitis: infection of the epididymis, the tube that carries sperm.
- Expedited partner therapy (EPT): treating a partner without a prior exam.
- Test of cure: a repeat test about 4 weeks after treatment.
- Doxy-PEP: 200 mg doxycycline within 72 hours after sex.
- Lymphogranuloma venereum (LGV): an invasive form of chlamydia caused by serovars L1 to L3.
Frequently asked questions
How does chlamydia start?
Through vaginal, anal or oral sex without a condom with an infected partner. Most people feel nothing; symptoms, if any, usually appear within about three weeks.
What are 5 signs of chlamydia?
Unusual discharge from the vagina or penis, burning when you pee, bleeding between periods or after sex, pain or swelling in a testicle, and rectal pain, discharge or bleeding. Many people have none of these.
How long does chlamydia take to go away?
Usually a week or two with the right antibiotic. Avoid sex until 7 days after a single dose or the end of a 7-day course, and retest about 3 months later.
Does chlamydia go away on its own?
Never wait for it to. Meanwhile it can spread to partners and, in women, to the uterus and tubes, causing pelvic inflammatory disease and infertility.
Is chlamydia curable?
Yes. Doxycycline for 7 days or, in some cases, a single dose of azithromycin cures chlamydia. You can catch it again, so partners need treatment.
What are the symptoms of chlamydia in men?
Discharge from the penis, burning when urinating and, less often, pain and swelling of one or both testicles. Many men have no symptoms at all.
Can you get chlamydia from oral sex?
Yes. Chlamydia can infect the throat through oral sex, usually without symptoms, and can be passed from the throat to a partner's genitals. If you have oral or anal sex, ask for swabs from those sites, because a urine test only checks the genital tract.
Sources
- Centers for Disease Control and Prevention — Chlamydial Infections, STI Treatment Guidelines 2021 — CDC, 2021 — cdc.gov
- Centers for Disease Control and Prevention — About Chlamydia — CDC — cdc.gov
- Centers for Disease Control and Prevention — Sexually Transmitted Infections Surveillance, 2024 (Provisional) — CDC, 2025 — cdc.gov
- Centers for Disease Control and Prevention — STI Screening Recommendations — CDC, 2021 — cdc.gov
- Centers for Disease Control and Prevention — Lymphogranuloma Venereum (LGV), STI Treatment Guidelines 2021 — CDC, 2021 — cdc.gov
- Centers for Disease Control and Prevention — Expedited Partner Therapy — CDC, 2024 — cdc.gov
- Bachmann LH et al. — CDC Clinical Guidelines on the Use of Doxycycline Postexposure Prophylaxis for Bacterial STI Prevention, United States, 2024 — MMWR Recomm Rep, 2024 — cdc.gov
- US Preventive Services Task Force — Chlamydia and Gonorrhea: Screening — USPSTF, 2021 — uspreventiveservicestaskforce.org
- MedlinePlus — Chlamydia Infections — National Library of Medicine — medlineplus.gov
- World Health Organization — Chlamydia fact sheet — WHO, 2025 — who.int
- US Food and Drug Administration — FDA Grants Marketing Authorization of First Home Test for Chlamydia, Gonorrhea and Trichomoniasis — FDA, 2025 — fda.gov
- Cleveland Clinic — Chlamydia: Causes, Symptoms, Treatment and Prevention — Cleveland Clinic — clevelandclinic.org
- Lau A et al. — Azithromycin or Doxycycline for Asymptomatic Rectal Chlamydia trachomatis — N Engl J Med, 2021 — doi.org
- Dombrowski JC et al. — Doxycycline Versus Azithromycin for the Treatment of Rectal Chlamydia in Men Who Have Sex With Men: A Randomized Controlled Trial — Clin Infect Dis, 2021 — doi.org
- Chen L et al. — Efficacy of doxycycline versus azithromycin for the treatment of rectal chlamydia: a systematic review and meta-analysis — J Antimicrob Chemother, 2021 — doi.org
- Luetkemeyer AF et al. — Postexposure Doxycycline to Prevent Bacterial Sexually Transmitted Infections — N Engl J Med, 2023 — doi.org
- Stewart J et al. — Doxycycline Prophylaxis to Prevent Sexually Transmitted Infections in Women — N Engl J Med, 2023 — doi.org
- Yamamoto S et al. — Doxycycline postexposure prophylaxis for sexually transmitted infections: a systematic review and meta-analysis with trial sequential analysis — Int J Infect Dis, 2026 — doi.org
- Usuanlele MT et al. — Antimicrobial Resistance Consequences of the Use of Doxycycline for Prevention of Bacterial Sexually Transmitted Infections: A Systematic Review — Sex Transm Dis, 2026 — doi.org
- Haggerty CL et al. — Risk of sequelae after Chlamydia trachomatis genital infection in women — J Infect Dis, 2010 — doi.org
- Hosenfeld CB et al. — Repeat infection with Chlamydia and gonorrhea among females: a systematic review of the literature — Sex Transm Dis, 2009 — doi.org
- Golden MR et al. — Effect of expedited treatment of sex partners on recurrent or persistent gonorrhea or chlamydial infection — N Engl J Med, 2005 — doi.org
- Lunny C et al. — Self-Collected versus Clinician-Collected Sampling for Chlamydia and Gonorrhea Screening: A Systemic Review and Meta-Analysis — PLoS One, 2015 — doi.org
- Abraham S et al. — Safety and immunogenicity of the chlamydia vaccine candidate CTH522: a first-in-human, randomised, double-blind, placebo-controlled, phase 1 trial — Lancet Infect Dis, 2019 — doi.org
- Pollock KM et al. — An investigation of trachoma vaccine regimens by the chlamydia vaccine CTH522 administered with cationic liposomes in healthy adults (CHLM-02): a phase 1, double-blind trial — Lancet Infect Dis, 2024 — doi.org
- Sanofi — Phase 1 Study of Chlamydia Trachomatis mRNA Vaccine in Adults (NCT06891417) — ClinicalTrials.gov, 2025 — clinicaltrials.gov
- EMBL-EBI — ChEMBL compound reports: doxycycline (CHEMBL1433), azithromycin (CHEMBL529), levofloxacin (CHEMBL33) — ChEMBL — ebi.ac.uk
Further reading
- Chlamydia rash: real causes and when to test
- Drug-resistant gonorrhea: your test explained
- Syphilis: symptoms, stages and blood tests
- Herpes: symptoms, genital herpes and treatment
- Human papillomavirus: symptoms, vaccine and tests
- Serology test: what an STI panel detects
- Ureaplasma: symptoms, testing and treatment
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