What Is Chlamydia?

Chlamydia is a sexually transmitted disease caused by Chlamydia trachomatis bacteria that is more common among sexually active teens and young adults.

Chlamydia is a common infection spread by sexual contact. While easily treated with antibiotics, many of the nearly three million women and men infected each year do not seek treatment—probably because they don't realize they have it. And that can lead to complications, including difficulty getting pregnant or carrying a pregnancy to term.

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Chlamydia Definition

Chlamydia is a sexually transmitted infection (STI) caused by Chlamydia trachomatis bacteria. You can get it by having vaginal, anal, or oral sex with someone who has the infection. Chlamydia bacterial infections are more common among sexually active teens and young adults.

Chlamydia may cause vaginal or penile discharge or a burning sensation during urination, among other symptoms. It can take time—usually one to three weeks—for symptoms to appear after having unprotected sex with someone who has the infection. Still, some people don't notice symptoms at all.

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Untreated chlamydia can cause permanent damage to a woman's reproductive system, leading to fertility problems and preterm birth. Because of this risk, sexually active women younger than 25 should get tested annually for chlamydia, even if they do not have symptoms. Testing is also recommended for women of any age who have an increased risk of chlamydia, like those with multiple sex partners, a new sex partner, or a partner with another STI.

A simple urine test can tell you whether you have chlamydia. If you test positive, you and your sex partner should be treated with antibiotics.


Symptoms and Signs of Chlamydia in Women

Chlamydia infects the cervix (the passageway connecting the vagina and uterus). Women often have no obvious signs of illness, especially soon after being infected. When symptoms do occur, common signs include a burning pain with urination, pain with intercourse, or an abnormal, smelly vaginal discharge.

Chlamydia can also cause rectal pain, discharge, or bleeding.

It's possible for infected body fluids to enter a sex partner's eye, causing the clear membrane protecting the outer layer of the eye to become inflamed. Chlamydia can infect the throat after unprotected oral sex, but it's less common and usually doesn't cause symptoms.

Since many women have no noticeable symptoms at all, they don't seek treatment, and that can set the stage for serious health problems.

Untreated cases of chlamydia make women more susceptible to other STIs, including HIV. Chlamydia can also lead to a more serious condition called pelvic inflammatory disease (PID). PID infects the reproductive organs. It can lead to an ectopic (tubal) pregnancy or miscarriage. Women with PID may struggle with infertility. The condition can also cause long-term pelvic pain.

Chlamydia symptoms in women may include:

  • Pain or burning while urinating
  • Abnormal, smelly vaginal discharge
  • Painful sex
  • Bleeding after sex
  • Frequent urge to urinate
  • Rectal pain or discharge
  • Bleeding between periods or heavier periods
  • Lower abdominal pain, nausea, or fever
  • Eye redness, pain, swelling, irritation, or discharge

Symptoms and Signs of Chlamydia in Men

Men get chlamydia too, and like women, they often don't have symptoms.

Chlamydia can infect the urethra, the tube that connects the bladder to the penis and allows urine to pass. Symptoms, if they surface, usually appear one to three weeks after a man is exposed to the infection. Chlamydia can cause a burning sensation during urination. Men may notice a clear or cloudy discharge from the tip of the penis.

In men, as in women, chlamydia can infect the anus, possibly leading to rectal pain or discharge. When bacteria-containing secretions enter the eyes, this STI can lead to eye pain and other symptoms. Less often, chlamydia can cause a throat infection, but there may not be any evidence of chlamydia in the mouth because it usually doesn't cause symptoms.

Chlamydia symptoms in men include:

  • Penile discharge
  • Burning pain during urination
  • Frequent urge to urinate
  • Pain in one or both testicles
  • Rectal pain, discharge, or bleeding
  • Eye redness, pain, swelling, irritation, or discharge

Causes of Chlamydia

Chlamydia is caused by bacteria called Chlamydia trachomatis. It's the most common sexually transmitted infection in the U.S., accounting for close to three million new infections each year.

Chlamydia infections are almost always passed along through unprotected vaginal, anal, or oral sex. One key exception: Babies born to mothers with chlamydia can pick up the infection during delivery.

Using condoms during sex and having sex with only one person (who has tested negative for chlamydia and other STIs) can reduce your risk of infection.


Chlamydia Is Contagious

Yes, chlamydia is contagious. Anyone who has sex with someone who has untreated chlamydia can get infected. Likewise, people with untreated chlamydia can spread the infection to their sex partners.

Chlamydia occurs more often in teens and young adults, particularly young women. The U.S. Centers for Disease Control and Prevention (CDC) estimate that one in 20 sexually active young women between the ages of 14 and 24 have chlamydia. Based on reported cases, women's rate of infection is about twice that of men. (That may reflect more testing of women.) Men who have sex with men are also at greater risk of chlamydia.

Abstaining from sex can prevent chlamydia infection. Using condoms and limiting the number of sex partners you have can also reduce your risk of infection.

How Do You Get Chlamydia?

Chlamydia is transmitted from person to person primarily through unprotected vaginal, anal, or oral sex. Anyone who is sexually active and doesn't use protection can get it, and that includes women who have sex with women and men who have sex with men.

Chlamydia is passed along when an infected person's body fluids, including semen, vaginal fluids, or anal secretions, come in contact with a partner's mucous membranes (the soft layer of tissue that protects organs and body cavities, including the mouth, vagina, penis, and anus).

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Sex toys can spread chlamydia. But can you get chlamydia from a toilet seat? No, the STI chlamydia isn't contracted through casual contact. You don't get it from sharing food or drinks, and you don't get it from someone's cough or sneeze. You also can't get chlamydia from kissing.

However, if semen, vaginal fluids, or anal secretions enter your eye during sex, you can get an eye infection. And babies born to moms with chlamydia may develop an eye infection or pneumonia from being exposed to the bacteria during delivery.


Chlamydia Testing

Chlamydia is often a silent infection, meaning most people with chlamydia don't have any symptoms. The only way to confirm a chlamydia diagnosis is to get tested. Simple lab tests can detect the presence of Chlamydia trachomatis bacteria.

It can take one to five days after unprotected sex for the infection to be detected. The preferred test is called a nucleic acid amplification test. It detects the bacteria's genetic material. There are other testing methods, but they're not as accurate.

Your doctor may swab your vagina or cervix (or a man's urethra via the opening at the tip of the penis) or collect a urine sample for testing. Rectal and throat samples may also be collected for chlamydia testing.

Testing is done any time a woman or man has symptoms, or when a sex partner has symptoms or is diagnosed with chlamydia. Young women should get tested annually. If they do have the infection, doctors can administer treatment before it causes long-term complications.

When To See a Doctor

Even if you don't have symptoms, make an appointment to see your doctor if you are sexually active and suspect you or your sex partner have chlamydia or another STI.

Your doctor will do an exam if you have symptoms such as discharge, pain, or bleeding. Seek immediate medical care if you have symptoms with a fever or if you have recurring symptoms after being treated.

See your doctor for an annual chlamydia test if you are a woman under 25 or if you are at high risk for chlamydia. (Risk factors include having a new sex partner, multiple sex partners, or a partner with an STI.) Untreated chlamydia can lead to serious complications, including pregnancy problems.

Men who have sex with men should also see a doctor for an annual chlamydia screening.

If you are diagnosed with chlamydia, tell any sex partners from the past 60 days to go to the doctor for chlamydia testing and possible treatment.

Chlamydia Treatment

Chlamydia is easily treated with a single dose or short course of oral antibiotics.

Doctors often prescribe azithromycin, a one-dose option that's safe for pregnant women. A seven-day course of doxycycline taken twice daily is another option for people who are not pregnant. Each is highly effective in treating chlamydia infection.

Other commonly prescribed antibiotics for chlamydia include erythromycin, levofloxacin, ofloxacin, and amoxicillin. These chlamydia medicines are taken for seven or 14 days. You need to take all of your medicine to cure chlamydia.

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Your sex partner should be tested and treated, too. To avoid spreading the infection, you should not have sex for seven days after taking a single dose of azithromycin or until after you've completed a longer treatment regimen.

Your doctor may recommend follow-up testing three months after chlamydia treatment to make sure you haven't been reinfected. (Repeat infections increase women's risk of serious chlamydia complications.)

Newborns with eye infections due to chlamydia may be prescribed oral erythromycin or azithromycin.

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Chlamydia medications

There are several medications currently approved to treat chlamydia.

  • azithromycin (Zithromax, AzaSite, Zmax): a single-dose treatment. (Infant dosing differs)
  • doxycycline (Oracea, Monodox, Vibra-Tabs): taken twice daily for seven days
  • erythromycin (Ilotycin, Erythra-Derm, Staticin): taken four times a day for seven or 14 days, depending on the dosage
  • levofloxacin (Levaquin, Quixin, Iquix): a once-daily, seven-day treatment
  • ofloxacin (Ocuflox, Floxin): taken twice daily for seven days
  • amoxicillin (Moxatag): an alternative treatment for pregnant women taken three times daily for seven days


Is chlamydia curable? Chlamydia is easily cured with antibiotics. The sooner you get tested and treated, the quicker it goes away. But women and men often don't realize they're infected because they don't notice or don't have any symptoms of chlamydia.

The longer chlamydia is left untreated, the greater the risk for serious complications. Women can develop a pelvic inflammatory disease, a complication that causes scarring of the fallopian tubes. It can lead to fertility problems and chronic pelvic pain.

Chlamydia infection during pregnancy can complicate pregnancy, sometimes leading to tubal pregnancy and preterm delivery. Chlamydia cannot kill you, but in some cases, tubal pregnancies, called ectopic pregnancies, can be fatal. Chlamydia infection can also be passed to the newborn during delivery.

Men whose chlamydia infection goes untreated can develop sore, swollen testicles.

People can have chlamydia more than once, and that can boost the risk for complications. If you have untreated chlamydia, you can pass it on to others without knowing it.

To protect yourself and your sex partners, use condoms and consider limiting the number of people you have sex with. If you test positive for chlamydia, tell your current and former partners from the past 60 days so that they can get tested and treated, too.

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