Chlamydia: Symptoms, Causes, Treatment, and How to Protect Yourself

4 days ago

11 min read

Updated: 2 days ago

Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026

Editorial note: This article is for educational purposes only and is not a substitute for professional medical advice. Always consult a qualified healthcare provider for diagnosis and treatment decisions. Last updated: August 2026.

TL;DR

Chlamydia is a common, curable bacterial STI that usually causes no symptoms, which is why routine screening matters. In the U.S., more than 2.2 million cases were reported in 2024, with the highest rates in people 25 and younger. It is treated with a short antibiotic course, partners from the last 60 days must also be treated, and you should be retested about three months after treatment.

Quick Answer

What is chlamydia, and can it be cured? Chlamydia is a sexually transmitted infection caused by the bacterium Chlamydia trachomatis. It is the most commonly reported STI in the United States and the most common curable STI worldwide, with an estimated 128.5 million new infections in adults in 2020. Most infections cause no symptoms, but untreated chlamydia can lead to pelvic inflammatory disease and infertility in women. It is fully curable with antibiotics, and retesting about three months after treatment is recommended.

What exactly is chlamydia?

Chlamydia is a common sexually transmitted infection caused by the bacterium Chlamydia trachomatis. It spreads through oral, vaginal, and anal sex, and can also pass from a pregnant person to a baby during delivery, where it can cause pneumonia or a serious eye infection in the newborn [1].

The infection most often affects young people. Sex before age 25 carries the highest risk, but chlamydia can occur in both men and women and in all age groups [1].

The reassuring part: chlamydia is not difficult to treat, and early treatment makes long-term problems unlikely. The danger lies in how quietly it spreads — many people never know they have it [1].

| Key fact | Detail | |---|---| | Cause | Chlamydia trachomatis bacterium | | Transmission | Vaginal, oral, anal sex; mother to baby during delivery | | U.S. cases (2024) | More than 2.2 million reported | | Global burden (2020) | ~128.5 million new infections in adults 15–49 | | Symptom rate | Majority of cases never develop symptoms | | Cure | Antibiotics — usually curable within 1–2 weeks |

Figure 1: The scale of chlamydia — the most reported STI in the U.S. (2.2 million+ cases in 2024) and the most common curable STI worldwide, with most cases staying symptom-free.

How big is the problem?

Chlamydia is the most commonly reported sexually transmitted infection in the United States. According to the latest national surveillance data, more than 2.2 million cases of chlamydia were reported in 2024. That figure declined about 8% from 2023, but the overall STI burden in the U.S. is still 13% higher than it was a decade ago [2] [3].

Worldwide, the numbers are far larger. In 2020 alone, an estimated 128.5 million new chlamydia infections occurred among adults aged 15–49. The global prevalence that year was estimated at 4.0% in women and 2.5% in men in that age group [4].

Rates are not distributed evenly. Chlamydia hits young people hardest — the infection rate is highest in sexually active people 25 and younger. Women are diagnosed at roughly twice the rate of men (recent surveillance shows about 621 per 100,000 women versus 364 per 100,000 men) [3] [5].

| Statistic | Value | Source year | |---|---|---| | U.S. reported cases | 2,200,000+ | 2024 | | Year-over-year change | Down ~8% | 2023 → 2024 | | Global new infections (adults 15–49) | ~128.5 million | 2020 | | Global prevalence, women 15–49 | 4.0% | 2020 | | Global prevalence, men 15–49 | 2.5% | 2020 | | U.S. rate, women vs. men (per 100,000) | ~621 vs. ~364 | Recent surveillance |

Why reported cases may understate reality: Because most infections cause no symptoms and go unscreened, the true number of infections is higher than reported surveillance figures. Research has estimated that about 77% of chlamydial infections never develop symptoms [6].

What are the symptoms of chlamydia?

Early-stage chlamydia infections often cause few or no symptoms. Even when symptoms do occur, they are usually mild — which is why regular screening is so important [1].

When symptoms do appear, they can differ by sex and by the site of infection.

| Site | Possible symptoms | |---|---| | Urethra/genitals (women) | Vaginal discharge, painful urination, bleeding between periods or after sex, painful vaginal sex, lower abdominal pain | | Urethra/genitals (men) | Discharge from the penis, burning with urination, testicular pain | | Eyes | Conjunctivitis — red, irritated inner eyelid | | Throat | Often no symptoms; sometimes sore throat | | Rectum | Often no symptoms; can cause rectal pain, discharge, or bleeding |

Symptoms may not appear until up to three weeks after exposure [4]. The infection can also spread in the opposite direction in time — damaging the reproductive system silently, long before anyone notices anything wrong [3].

When to see a healthcare provider: seek care if you have discharge from your vagina, penis, or rectum, or pain during urination. Also see a provider if you learn that a sexual partner has chlamydia — treatment may be prescribed even if you have no symptoms [1].

How does chlamydia spread?

The bacterium spreads most commonly through vaginal, oral, and anal sex. It can also pass from a pregnant person to their baby during vaginal delivery, where it can cause pneumonia or a serious eye infection in the newborn [1].

Unprotected sex is the main driver. Using a condom correctly during every sexual encounter lowers — but does not eliminate — the risk of infection [1].

Several factors raise the odds of infection:

| Risk factor | Why it matters | |---|---| | Sex before age 25 | Highest infection rate of any group | | Not using a condom (or incorrect use) | Removes the main barrier | | New or multiple sex partners | More exposure opportunities | | Changing partners before knowing a partner's status | Infection can already be present | | Less use of STI prevention services | Infections go unscreened and untreated | | Current infection with another STI | A marker of higher-risk exposure |

What happens if chlamydia goes untreated?

Left untreated, chlamydia can cause serious — sometimes permanent — damage, especially in women [1] [3].

| Complication | What it involves | |---|---| | Pelvic inflammatory disease (PID) | Infection of the uterus and fallopian tubes; severe cases may require hospital care; can damage the fallopian tubes, ovaries, uterus, and cervix | | Infertility | Scarring and obstruction of the fallopian tubes can make pregnancy difficult or impossible | | Ectopic pregnancy | A fertilized egg implants outside the uterus, usually in a fallopian tube; can cause life-threatening complications such as a burst tube | | Epididymitis (men) | Inflammation of the tube beside each testicle, causing fever, scrotal pain, and swelling | | Prostatitis (men, rare) | Infection of the prostate gland, causing pain, fever, chills, and urinary pain | | Newborn infections | Pneumonia or serious eye infection passed during vaginal delivery | | Reactive arthritis (Reiter syndrome) | Affects the joints, eyes, and urethra | | Increased HIV risk | Untreated chlamydia may raise the chance of getting or transmitting HIV |

Men rarely have long-term problems from chlamydia, but in rare cases the infection near the testicles can affect fertility [3]. Untreated infection may also increase the risk of HIV acquisition and transmission [4].

How is chlamydia diagnosed?

Testing is simple and painless. Healthcare providers analyze a sample of cells, which can be collected two ways [2]:

| Test type | How it works | |---|---| | Urine test | A urine sample analyzed in the lab; available for males and females | | Swab | A sample from the cervix, vagina, throat, or anus collected on a swab; vaginal swabs can be self-collected and can be done during a routine Pap test |

At-home tests are now available without a prescription. If an at-home test comes back positive, see a healthcare provider to confirm the diagnosis and start treatment [2].

The gold-standard laboratory method is nucleic acid amplification testing (NAAT), which can be performed in the lab or at the point of care [4].

Who should get screened, and how often?

| Group | Screening guidance | |---|---| | Sexually active women 25 or younger | Yearly — this group has the highest infection rate | | Women 25+ | Yearly only if at increased risk | | Pregnant people | Screening at the first prenatal exam; retest later in pregnancy if high risk | | Sexually active men who have sex with men | Yearly | | Anyone with a new or multiple partners | Consider more frequent screening | | Anyone with symptoms or an infected partner | Test right away, regardless of screening schedule |

Even if you were tested within the past year, get tested again when you have a new sex partner [2].

How is chlamydia treated?

Chlamydia is cured with antibiotics. Treatment is typically either a seven-day course or a one-time dose of medicine. In most cases, the infection clears within one to two weeks after starting antibiotics [2].

Important points during treatment:

Avoid sex from the start of treatment until all symptoms are gone. You can still spread the infection at first [2]. If you receive a single dose, wait seven days before having sex; if you receive a seven-day course, wait until all doses are finished [3].
All sexual partners from the last 60 days need screening and treatment, even if they have no symptoms. Otherwise, the infection gets passed back and forth between partners [2].
Retest three months after treatment. The CDC recommends repeat testing to make sure you have not been reinfected — reinfection can happen if partners were not treated or new partners carry the bacteria [2] [3].
Past infection does not protect you. Having chlamydia once — or being treated for it — does not prevent you from getting it again [2].

Medicine stops the infection but does not undo damage already done, so earlier treatment means better protection of long-term health [3].

A note on preventing infection before it happens

For people at higher risk of chlamydia — including men who have sex with men and transgender women — a medication called doxycycline may be an option. Taken within 72 hours (3 days) of sexual activity, it lowers the risk of bacterial STI infection. A healthcare provider can prescribe it along with appropriate testing [1].

Can chlamydia be prevented?

The only sure way to avoid chlamydia is to abstain from vaginal, anal, and oral sex. Short of that, a combination of practical steps cuts risk substantially [1] [3]:

| Prevention step | What it does | |---|---| | Use condoms every time | Correctly used condoms lower (but do not eliminate) infection risk | | Limit the number of sex partners | Multiple partners raise risk significantly | | Get regular screenings | Catches silent infections before complications develop | | Choose a mutually monogamous tested partner | Long-term monogamy with a tested partner lowers exposure | | Consider doxycycline PEP if high-risk | Taken within 72 hours of exposure for certain higher-risk groups | | Treat all partners | Prevents ping-pong reinfection |

There is currently no vaccine for chlamydia [4].

Figure 2: From swab or urine sample to cure — the testing, treatment, and partner-notification steps that stop chlamydia from cycling through relationships.

What should you do if a partner has chlamydia?

If a sexual partner tells you they have chlamydia — or tests positive for it — act promptly [1] [2]:

See a healthcare provider for screening and, very likely, treatment, even if you feel fine.
Avoid sexual contact until you and all exposed partners have completed treatment.
Ask about screening for other STIs — infections often travel in groups.
Keep the 60-day rule in mind: partners from the last 60 days need evaluation.

What happens after treatment — and what doesn't change?

Treatment cures the current infection, but it does not create immunity. You can get chlamydia again, so the habits that protect you — condoms, honest conversations with partners, regular screening — remain just as important after a cure as they were before [2] [3].

Figure 3: Warning signs that warrant prompt care — from discharge and painful urination to newborn pneumonia and eye infection risks after delivery.

The bottom line

Chlamydia is the most reported STI in the United States and the most common curable STI in the world — yet most people who carry it never feel a thing. That silence is precisely why screening matters: more than 2.2 million cases were reported in 2024 alone, with the highest rates in people 25 and younger. The good news is that a short antibiotic course cures the infection, and retesting at three months confirms the cure has held.

If you have symptoms, a positive test, or an exposed partner, see a healthcare provider promptly — treatment is quick, and early care protects your long-term health.

Frequently asked questions

How do you know if you have chlamydia?

You often cannot tell. Most chlamydia infections cause no symptoms at all, and an estimated 77% of infections never develop symptoms. When symptoms do appear — typically within three weeks of exposure — they include unusual discharge, burning with urination, bleeding between periods, and pelvic or testicular pain. A urine test or swab is the only reliable way to know.

How long does it take to cure chlamydia?

Antibiotics cure most infections within one to two weeks of starting treatment. Courses are either seven days or a single dose. You should avoid sex from the start of treatment until all symptoms are gone — seven days after a single dose or until a seven-day course is finished — and get retested about three months later to confirm the cure has held.

Can chlamydia go away on its own?

No. Chlamydia requires antibiotics to clear. Left untreated, it can persist and cause serious complications, including pelvic inflammatory disease, infertility, and ectopic pregnancy in women, and epididymitis in men.

Does chlamydia cause infertility?

It can, if untreated. Chlamydia can scar and obstruct the fallopian tubes, making pregnancy difficult or impossible and raising the risk of ectopic pregnancy. This is one reason early detection and treatment matter so much — cured infection stops the damage before it becomes permanent.

Can you get chlamydia from kissing or a toilet seat?

No. Chlamydia spreads through vaginal, oral, and anal sex, and from mother to baby during delivery. It is not spread by casual contact such as kissing, hugging, sharing food, or touching surfaces like toilet seats.

Should my partner get tested too?

Yes. All sexual partners from the last 60 days should be screened and treated even if they have no symptoms. Without partner treatment, chlamydia is commonly passed back and forth, causing reinfection after your own cure.

Can you get chlamydia more than once?

Yes. Having chlamydia or being treated for it does not create immunity. You can be reinfected by an untreated or new partner, which is why retesting about three months after treatment is recommended and why condoms remain important.

Is chlamydia dangerous during pregnancy?

It can be. An infected pregnant person can pass chlamydia to the baby during vaginal delivery, causing pneumonia or a serious eye infection in the newborn, and infection during pregnancy is also linked to prematurity and low birth weight. Screening at the first prenatal visit — with retesting if risk factors are present — and prompt treatment protect the baby.