Chlamydia

One of the most common sexually transmitted infections in the United States. Most people who have it notice nothing at all — which is why testing, not symptoms, is what tells you.

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Why test for chlamydia?

Most people have no symptomsMost infections cause nothing noticeable in either women or men, so symptoms are not a way to rule it out.

It is the most reported STI in the U.S.Over 1.6 million reported cases a year, more than any other.

Untreated, it causes lasting damageIt can affect fertility and cause pelvic inflammatory disease.

Treatment is straightforwardA short course of antibiotics clears it when caught early.

When can I test?

Chlamydia does not show up immediately after exposure.

1Wait for the window to passIncubation is 7 to 21 days, most often 7 to 14. Testing sooner can return a negative result even when an infection is present.

2Give the right sampleA vaginal swab is more sensitive than urine for women and can be self-collected; urine is used for men.

3Results in 1-2 daysIf positive, treatment is a short antibiotic course and a retest afterwards.

What Is Chlamydia?

Chlamydia is one of the most common sexually transmitted infections (STIs) in the United States and worldwide, caused by the bacterium Chlamydia trachomatis. It can affect people of all ages but is especially prevalent among adolescents and young adults. Most people with chlamydia have no symptoms, so the infection often goes undetected. If left untreated, chlamydia can lead to serious health problems, but it is easily cured with antibiotics.

How is chlamydia spread?

Chlamydia is transmitted through vaginal, anal, or oral sex with someone who has the infection. It can also be spread by sharing sex toys that have not been washed or covered with a new condom. Pregnant women can pass chlamydia to their babies during childbirth, which can result in eye infections or pneumonia in newborns.

How is chlamydia treated?

Chlamydia is cured with a short course of antibiotics prescribed by a healthcare provider. Take the full course even if symptoms stop early, and avoid sex until you and any partners have completed treatment. Treatment clears the infection but does not undo damage already done, and it does not protect you from catching it again. The CDC advises retesting about three months after treatment, because reinfection from an untreated partner is common.

How common is chlamydia?

Reported cases in the United States, 2000–2023

1,648,568reported cases, 20234.3×change since 2000

20002023

2023: 1,648,568 reported cases nationally, a rate of 492.2 per 100,000 — stable against 2022, a change of under 1%.

2023 is the CDC published national total.

Reported rate per 100,000, by age and sex (2023)

Age	Women	Men
15-19	2,843	1,198
20-24	3,435	1,557
25-29	1,902	762
30-34	857	377
35-39	359	181
40+	69	36

Almost half (48.2%) of all reported chlamydia, gonorrhea and syphilis cases in 2023 were among people aged 15 to 24.

Highest rates by state

LA789 per 100k
36,200 cases

MS781 per 100k
22,968 cases

AK728 per 100k
5,338 cases

SC673 per 100k
35,525 cases

GA666 per 100k
72,662 cases

Other infections

Chlamydia often occurs alongside other STIs. Many panels screen for several at once.

GonorrheaOften occurs alongside chlamydiaView →SyphilisFour stages, curable at any of themView →HerpesHSV-1 and HSV-2View →HIVWindow period varies by testView →HepatitisA, B and CView →HPVThe most common STI overallView →TrichomoniasisThe most common curable STIView →MycoplasmaWhen symptoms keep coming backView →

Sources

Last reviewed September 2026. This page is informational and is not medical advice. Where a figure cannot be sourced it is not stated.