Untreated chlamydia can quietly damage the reproductive tract over months to years, even when you feel completely fine. In women it can climb to the uterus and tubes and cause pelvic inflammatory disease, scarring, infertility, and ectopic pregnancy; in men it can inflame the testicular ducts. Chlamydia is curable, so the fix is testing and antibiotics.
| Item | Reported cases |
|---|---|
| Chlamydia | 1,648,568 |
| Gonorrhea | 601,319 |
| Syphilis (P&S) | 53,007 |
The essentials: what chlamydia is and why ignoring it matters
Chlamydia is caused by the bacterium Chlamydia trachomatis, and most genital infections in the US come from the serovars labeled D through K CDC. It's the most commonly reported bacterial STI in the country — roughly 1.65 million cases reported in 2023, a rate of about 492 per 100,000, and the numbers have stayed roughly flat across 2020–2023 CDC AtlasPlus, 2023. Rates aren't uniform: Washington DC, Louisiana, and Mississippi run more than double the national rate.
The reason untreated chlamydia is dangerous is precisely that it's so easy to miss. About three quarters of infected women and half of infected men have no symptoms at all. A 'silent' infection isn't a harmless one — the bacterium can keep replicating in the cervix or urethra and travel upward. In women, the worry is pelvic inflammatory disease (PID), an infection of the uterus, fallopian tubes, and surrounding tissue. PID can scar the tubes, which raises the risk of infertility and of ectopic pregnancy (a pregnancy that implants outside the uterus, which is a medical emergency). It can also leave behind chronic pelvic pain. In men, untreated infection can cause epididymitis — inflammation of the coiled tube behind the testicle that stores sperm — which is painful and, less commonly, can affect fertility.
This is why screening guidance is deliberately asymmetric. The USPSTF gives a Grade B recommendation — meaning screen — for sexually active women age 24 and under, but an I-statement (insufficient evidence) for screening men, because the heaviest complication burden falls on women USPSTF.
Symptoms of chlamydia (and what 'silent' really means)
Most people who carry chlamydia notice nothing, which is the whole problem. When symptoms do appear, they tend to be mild and easy to write off as a minor irritation. Here's what each site of infection can look like.
In women
Women may have abnormal vaginal discharge or burning with urination. If the infection spreads upward toward PID, the picture changes: lower abdominal or low-back pain, fever, pain during intercourse, and bleeding between periods. Those upper-tract symptoms are a signal to be seen quickly, because that's the stage where lasting damage happens.
In men
Men may notice penile discharge that's often clear or cloudy — sometimes just a single drop in the morning — along with burning on urination or burning and itching at the tip of the penis. Testicular pain or swelling points toward epididymitis and should be evaluated.
Rectal and throat infections
Rectal infection can cause anal pain, discharge, or bleeding, but it's frequently silent. Throat (pharyngeal) infections are typically asymptomatic. Because these sites give no warning, they're caught only when you specifically test for them — a key reason to tell your clinician about all the kinds of sex you have.
Lymphogranuloma venereum (LGV)
A more invasive form of chlamydia, caused by the L1, L2, and L3 serovars, is called lymphogranuloma venereum. It's seen most 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, painful urge to pass stool even when the rectum is empty) CDC LGV. LGV needs a longer antibiotic course than ordinary genital chlamydia.
Testing: how to confirm or rule it out
The recommended and most accurate method is a NAAT — a nucleic acid amplification test — which works for both genital and extragenital (rectal, throat) infection CDC STI Tx Guidelines, 2021. NAATs can run on several specimen types: a first-catch urine sample, a self- or clinician-collected vaginal swab, an endocervical swab, a male urethral swab, or rectal and pharyngeal swabs.
In practice, testing is simpler than people fear. You'll usually pee into a cup (hold your urine for about an hour beforehand for a cleaner first-catch sample) or do a quick self-collected swab. There's no blood draw and no dreaded urethral swab for routine screening, and many clinics text results in a day or three. It's free or low-cost at Planned Parenthood, health departments, and Title X clinics, frequently $0 with insurance; at-home kits run roughly $50–150.
One common mistake undercuts all of this: testing the morning after a possible exposure. A NAAT is most reliable about two weeks out, so a too-early negative can be falsely reassuring. If you're timing a test around a specific encounter, see when to test after exposure and then get tested at the right point.
Treatment: chlamydia is curable
Yes — the right antibiotics cure chlamydia. The preferred regimen is doxycycline, taken as a 7-day course CDC. Take it with food and avoid strong sun, since doxycycline can make skin more sensitive. Alternatives include a single dose of azithromycin or a 7-day course of levofloxacin. In pregnancy, a single dose of azithromycin is preferred, with amoxicillin as an alternative.
Doxycycline became first-line in the 2021 guidelines for a concrete reason: it clears rectal chlamydia far better than the old single-dose azithromycin. A randomized trial found doxycycline cured 100% of rectal infections versus 74% with azithromycin Rectal CT RCT, and azithromycin also showed higher microbiologic treatment failure in men. If you're weighing the two options, see azithromycin vs doxycycline for chlamydia, and for the full regimen details read up on chlamydia treatment.
| Regimen | How it's taken | Best use |
|---|---|---|
| Doxycycline (preferred) | Oral, twice daily for 7 days | First-line for genital and rectal infection |
| Azithromycin (alternative) | Single oral dose | Pregnancy; when adherence to a 7-day course is a concern |
| Levofloxacin (alternative) | Oral, once daily for 7 days | When doxycycline and azithromycin aren't suitable |
Treating your partners is part of the cure, not an afterthought. Refer, test, or presumptively treat any partner from the prior 60 days, and abstain from sex for 7 days after single-dose therapy or until you finish the 7-day course. This isn't bureaucratic caution — in a landmark trial, giving patients medication to deliver to partners (expedited partner therapy, or EPT) measurably cut persistent and repeat infection NEJM EPT RCT. EPT is permissible in most but not all US states, so verify your local status.
After treatment, put a reminder in your calendar: everyone should be retested about three months later. That retest catches reinfection — usually from an untreated partner — not treatment failure, which is why it's called the 3-month retest and not a test-of-cure. A true test-of-cure isn't advised for non-pregnant people unless adherence is in doubt, symptoms persist, or reinfection is suspected; pregnant people get a test-of-cure about four weeks after finishing and then retest at three months. More on the why behind retesting is in chlamydia reinfection.
Prevention that actually moves the needle
Condoms used correctly every time lower your risk, and a long-term mutually monogamous relationship with a tested partner is protective. But because most infections are silent, the interventions that do the heavy lifting are routine screening and getting partners treated — you can't avoid a risk you can't feel.
One newer tool is DoxyPEP: a single 200 mg dose of doxycycline taken within 72 hours after sex, which reduced chlamydia by more than 70% in studies CDC DoxyPEP, 2024. It's offered to men who have sex with men and to transgender women who've had a bacterial STI in the past year. Read more at CDC DoxyPEP.
- Get screened on the schedule that fits your age and activity — for women 24 and under who are sexually active, that's routine, not optional.
- Treat partners from the last 60 days so you don't bounce the same infection back and forth ('ping-pong' reinfection).
- Finish the full 7-day doxycycline course even after symptoms fade.
- Schedule your 3-month retest before you leave the appointment.
- Ask whether DoxyPEP fits your situation if you're eligible.
When to see a clinician
See a clinician if you have any genital symptoms — discharge, burning, pelvic or testicular pain, bleeding between periods — or if a partner tells you they tested positive. Lower abdominal pain with fever in a woman, or testicular pain and swelling in a man, deserves prompt attention because those suggest the infection has spread. And if you've had a possible exposure but feel fine, that's still the moment to screen — the silent infections are exactly the ones that cause trouble down the line. Testing positive is routine and curable, not a character verdict; clinics handle it every day, and in many states you can notify partners anonymously.