Chlamydia is a sexually transmitted infection (STI) that spreads via oral, vaginal, or anal sex. It does not require the presence of semen to transmit and most commonly does not produce any early symptoms. It can also pass to a baby during childbirth.

As most people do not experience symptoms of chlamydia, it can go undetected. For some individuals, chlamydia can develop into a serious infection that may damage the reproductive system or cause other health issues.

Tests for chlamydia include urine samples and vaginal swabs. The lab processes these to detect the Chlamydia trachomatis bacteria and recommend the appropriate treatment.

This article discusses how often chlamydia goes undetected, as well as chlamydia complications, symptoms, treatment, and more.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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According to the Centers for Disease Control and Prevention (CDC), chlamydia was the most common STI that people reported in 2020.

There were 1.6 million cases — more than double the number of gonorrhea, syphilis, or congenital syphilis cases.

The bacteria C. trachomatis is responsible for chlamydia infections. It transmits through vaginal, oral, or anal contact and, in most cases, does not produce any symptoms. For this reason, it often goes undetected and spreads quickly.

It is difficult to account for many cases of chlamydia because they can go undetected and thus unreported.

Any sexually active individual can acquire chlamydia, which is very common among young people. Rates are also higher among men who have sex with men.

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Find out more about chlamydia.

People sometimes refer to chlamydia as a “silent” infection as it produces no symptoms.

The CDC reports that studies vary on the number of people who develop symptoms. Two studies estimate that, out of those with chlamydia, about 10% of males and about 5–30% of females develop symptoms. It can take several weeks for symptoms to show.

In females, chlamydia can infect the cervix, producing discharge and bleeding.

In both males and females, it can infect the urethra, producing signs of urethritis.

Possible symptoms in males include:

In females:

If the infection affects the rectum, there may be rectal pain, discharge, or bleeding.

It can also cause the eye infection conjunctivitis if genital secretions enter the eye.

Untreated chlamydia can cause serious complications in males and females.

Sometimes, chlamydia infections can lead to other infections, such as conjunctivitis or rectal infections.

Having a chlamydia infection can also increase a person’s chances of contracting HIV.

Complications in females

When females do not receive treatment for chlamydia, pelvic inflammatory disease (PID) can occur. This can lead to scar tissue inside the fallopian tubes, eventual blockage, ectopic pregnancy, infertility, and long-term pain.

PID can sometimes lead to perihepatitis, also called Fitz-Hugh-Curtis syndrome. This results in inflammation of the liver capsule and peritoneum and produces pain in the right upper portion of the abdomen.

Untreated chlamydia during pregnancy can cause early delivery, conjunctivitis, and pneumonia in the infant.

Complications in males

Untreated chlamydia in males can cause reactive arthritis. This is when the body responds to bacteria with inflammation. It typically causes pain in the joints, eyes, or urinary tract.

Chlamydia infection in males can also spread to the tubes attached to the testicles, causing testicular pain. This can lead to infertility, though this is rare.

It is important for a sexually active person to regularly test for chlamydia, even if they have no symptoms. Testing for an infection or disease in asymptomatic people is known as screening.

A 2021 literature review found that chlamydia screening in asymptomatic females significantly reduced the risk of PID compared to no screening.

To self-screen for chlamydia, a person can order testing kits online or from a sexual health clinic. The kit will have all the equipment a person needs, along with instructions. They can then perform the test themselves at home and send it to the clinic in the mail.

Alternatively, they can visit a clinic in person to receive a test.

A doctor may want to know about a person’s sexual history. They should be honest and upfront about their sexual partners and which barrier methods they use.

To test for chlamydia, a doctor will ask for a urine sample and possibly a vaginal, rectal, or throat swab.

A medical staff member may collect the sample or allow the person to collect it themselves.

For a chlamydia test, a person may have to provide:

  • A sample of first-catch urine: Use a sterile cup to collect urine from the first part of the urine stream. Do not urinate for 2 hours before the test.
  • A swab sample: Use a sterile swab to gather cells from the genital, rectal, or throat area.

They will send the samples to a lab where technicians run tests to detect chlamydia bacteria.

The person should receive the test results within a few weeks. The clinic may call or text the person or issue a letter with the results.

There are no known risks to undergoing a chlamydia test.

Is testing accurate?

If a person follows the instructions carefully and provides the right samples, chlamydia testing will be accurate.

To receive the most accurate test, a person may wish to visit a clinic in person and have a medical professional take the samples.

A person can provide an accurate test by:

  • Avoiding urinating for 2 hours before they do the test.
  • Washing their hands thoroughly before conducting the test.
  • Sanitizing the area where they will place the test kit.
  • Reading the instructions thoroughly before opening the kit.
  • Making sure all the equipment in the kit is sterile and the package seals are unbroken.
  • Taking care when removing swabs from the packages, making sure not to drop them or let them touch anything.
  • Following the test kit instructions very carefully.

Doctors use antibiotics to treat chlamydia.

If a person with chlamydia receives treatment, they should not have intercourse for 7 days until their symptoms are gone. This is because reinfection can occur during treatment.

Medications will cure the primary infection but will not repair long-term damage. This is why it is important to test regularly for chlamydia so treatment can begin early, whether symptoms are present or not.

The only way to completely prevent chlamydia is to abstain from vaginal, oral, or anal sex.

However, using condoms during sex is the next best solution to preventing STIs such as chlamydia. If people use them correctly every time they have sex, they are less likely to get chlamydia.

A person may wish to take measures to reduce their risk of contracting chlamydia, including reducing the number of sexual partners and making sure any partners regularly test for STIs.

To avoid reinfection with chlamydia, a person should abstain from sexual activity during treatment.

When treatment has finished, they should continue to use condoms correctly every time they have sex.

Limiting the number of sexual partners will make a person less likely to contract chlamydia again. All sexual partners should get tested for chlamydia and receive necessary treatment before resuming any sexual activity.

This section answers some common questions about undetected chlamydia.

How long can someone have chlamydia without knowing?

If no symptoms arise, a person could go for years without knowing they have chlamydia.

This is particularly true for males, as they rarely experience complications from chlamydia.

Females have a slightly greater chance of developing complications, such as PID, if they contract chlamydia.

A sexually active person with chlamydia symptoms must inform their sexual partners to get tested.

Can chlamydia go undetected on a test?

If a person follows the instructions on the test exactly, the test should be accurate in detecting or ruling out chlamydia.

Can chlamydia be dormant and undetected?

While some internet rumors state that chlamydia can be “dormant” and go undetected on tests, no reputable sources support this.

Chlamydia bacteria can be present in the body without causing symptoms, but it will still appear on laboratory testing.

Chlamydia is highly curable with proper antibiotic treatment.

Chlamydia is an STI. A person can contract it through oral, vaginal, or anal sex.

It generally does not produce symptoms and often goes undetected.

Tests for chlamydia are highly accurate and simple to take. For males, tests are generally a urine sample. For females, tests may consist of a urine sample, vaginal swab, or both.

Chlamydia screening in asymptomatic people can prevent long-term damage to the reproductive system and the potential for chronic pain.