Talking about chlamydia matters because it's the most commonly reported bacterial STI in the US, yet most people who have it feel nothing. Roughly three quarters of infected women and half of infected men have no symptoms CDC, so silence lets it spread and scar. Open conversation drives routine screening, which is what actually catches it.
Comparison
| Item | Value |
|---|---|
| US national | 492 |
| Washington DC | 1,228 |
| Louisiana | 792 |
| Mississippi | 701 |
What chlamydia actually is
Chlamydia is an infection caused by the bacterium Chlamydia trachomatis, and most US genital infections come from a group of bacterial strains known as serovars D through K. Because it's a bacterium, it responds to antibiotics, and the right course clears it. You can learn more about the basics on our chlamydia overview.
It earns the label "the silent epidemic." About 1.65 million cases were reported in 2023 (492 per 100,000), and the numbers stayed roughly flat from 2020 through 2023 CDC, 2023, then began to ease. CDC's most recent surveillance even showed two consecutive years of decline, with provisional data showing about an 8% decline after 2023 CDC. The burden isn't even. Washington DC (1,228 per 100,000), Louisiana (792), and Mississippi (701) all run more than double the national rate. Globally, the WHO estimated 128.5 million new infections among adults aged 15–49 in 2020 WHO.
Symptoms, and the silent reality
Chlamydia usually has nothing to say for itself, which is what keeps the silence going. When symptoms do appear, they typically show up within one to three weeks after exposure, but most infections never reach that point.
- Women may notice abnormal vaginal discharge and burning on urination. If the infection climbs into the upper reproductive tract, it can cause lower abdominal or low-back pain, fever, pain during intercourse, and bleeding between periods, all signs the infection is doing damage.
- Men may see penile discharge that's clear or cloudy, sometimes only a single drop in the morning, plus burning on urination and burning or itching at the tip. Testicular pain or swelling can occur when it spreads.
- Rectal infection can cause pain, discharge, or bleeding, but it's frequently silent.
- Throat (pharyngeal) infections are typically asymptomatic, so you won't feel them at all.
If you wait to feel sick before testing, you'll often wait forever, and meanwhile pass it along or let complications build.
How chlamydia spreads
Chlamydia spreads through vaginal, anal, or oral sex. A pregnant woman can also pass it to her baby during childbirth. The bacterium lives on mucous membranes (genital, rectal, and throat), so any of those sites can be infected and any can transmit. Transmission needs no symptoms, no ejaculation, no visible signs, so partners reinfect each other in a "ping-pong" loop unless both get treated.
How chlamydia is tested
The recommended test is a nucleic acid amplification test, or NAAT, the most sensitive assay available, with specificity close to lab culture, and the method of choice Diagnostic Procedures to Detect. It works on several specimen types: first-catch (first-void) urine, endocervical, vaginal, male urethral, rectal, and pharyngeal swabs. For most people that means a urine cup or a self-collected swab, with no blood draw and no dreaded urethral swab.
In practice, you hold your urine for about an hour, fill a first-catch cup, and results are often texted back within one to three days. People often test the morning after a hookup, which is too soon. A NAAT is most reliable around two weeks out, so an early negative can mislead you. If you're timing a test, see when to test after exposure before you book.
Access is wide and often free. Planned Parenthood, health departments, and Title X clinics offer free or low-cost testing; at-home kits run roughly $50–150; and it's frequently $0 with insurance. You can get tested or compare testing providers to find the option that fits your situation.
Screening guidance is deliberately asymmetric. The USPSTF (Grade B, 2021) recommends screening all sexually active women aged 24 or younger and older women at increased risk, including during pregnancy; for men, it issues an I-statement, since the evidence is insufficient, because the heaviest complication burden (PID, infertility) falls on women USPSTF, 2021. CDC additionally recommends at least annual screening for sexually active men who have sex with men at all sites of exposure (urine, rectal, pharyngeal), and every three to six months for those at higher risk, plus HIV testing for everyone diagnosed with chlamydia.
Treatment: what it looks like
Chlamydia is curable with a short, standard course of antibiotics. The preferred regimen is doxycycline 100 mg orally twice daily for 7 days; alternatives include azithromycin 1 g as a single dose, or levofloxacin 500 mg once daily for 7 days CDC, 2021. In pregnancy, azithromycin 1 g as a single dose is preferred because doxycycline is contraindicated (an alternative is amoxicillin 500 mg three times daily for 7 days).
Azithromycin used to be co-equal but was downgraded: microbiologic treatment failure in men was higher with it, and doxycycline clears rectal infection far better. One randomized trial found 100% cure with doxycycline versus 74% with single-dose azithromycin for rectal chlamydia RCT, the main reason the 2021 guidelines made doxycycline first-line.
A few practical notes. Take doxycycline with food and avoid strong sun, since it raises sunburn risk. Abstain from sex for 7 days after single-dose therapy, or until you finish the 7-day course. Get partners from the prior 60 days tested or presumptively treated. Expedited partner therapy (EPT), where you carry medication to your partner, is permissible in most but not all states, so verify local rules. A landmark trial showed EPT measurably cut repeat infection. And put your retest on the calendar.
Why you retest at three months
CDC recommends retesting everyone treated for chlamydia about three months after treatment, regardless of whether you think your partners were treated CDC. This catches reinfection, not treatment failure, and it isn't a test-of-cure. A test-of-cure is not advised for non-pregnant people unless adherence is in question, symptoms persist, or reinfection is suspected. Pregnant patients are the exception: they get a test-of-cure about four weeks after finishing treatment and a retest at three months.
What happens if chlamydia goes untreated
Silence has consequences, and they fall unequally. Screening women under 25 is a Grade B recommendation because untreated infection in women can scar the reproductive tract. See our deeper guide to untreated chlamydia for the full picture.
- Pelvic inflammatory disease (PID), infection spreading into the uterus and fallopian tubes, causing inflammation and pain.
- Fallopian-tube scarring, which can block the tubes and lead to infertility.
- Ectopic pregnancy, a pregnancy that implants outside the uterus, which is a medical emergency.
- Chronic pelvic pain, a lasting consequence of tube and pelvic inflammation.
- In men, epididymitis, inflammation of the coiled tube behind the testicle that causes pain and fever and, rarely, sterility.
- Reactive arthritis (once called Reiter syndrome), a joint inflammation that can follow infection.
- In newborns exposed during birth, chlamydia is a leading cause of early infant pneumonia and conjunctivitis (eye infection).
- Chlamydia may increase the risk of acquiring or transmitting HIV.
How to prevent chlamydia
Condoms used correctly every time reduce risk, and a long-term mutually monogamous relationship with a tested partner lowers it further. But because most infections are silent, routine screening and treating partners interrupt transmission far more than condoms alone. See preventing chlamydia for the full strategy.
There's also a newer option. In 2024, CDC issued its first guidelines on doxycycline postexposure prophylaxis (DoxyPEP): a single 200 mg dose of doxycycline taken within 72 hours after sex CDC. Across three large randomized trials, it reduced chlamydia and syphilis by more than 70% and gonorrhea by roughly 50% CDC, 2024. It's offered to men who have sex with men and transgender women who've had a bacterial STI in the prior 12 months.
A note on LGV
Lymphogranuloma venereum (LGV) is caused by more invasive strains of C. trachomatis (serovars L1, L2, L3). Its burden is highest among men who have sex with men, and it usually shows up as proctocolitis: mucoid or bloody rectal discharge, anal pain, and tenesmus (a constant urge to pass stool). LGV needs a longer course of doxycycline 100 mg twice daily for 21 days CDC.
When to see a clinician
See a clinician if you have any symptoms (discharge, burning, pelvic or testicular pain, rectal bleeding), or if a partner tests positive, even if you feel fine. If you're a sexually active woman 24 or under, you're due for routine annual screening regardless of symptoms. Testing positive is routine and curable. Clinics handle chlamydia every single day, and in many states you can notify partners anonymously.
Keep exploring on EasySTD: what STD testing costs, your risk of an STD and Chlamydia testing.