Chlamydia is the most commonly reported sexually transmitted infection in the United States. A Chlamydia infection is caused by the bacterium Chlamydia trachomatis.  There are about four million cases of Chlamydia in the United States every year.

Chlamydia can be transmitted during vaginal, anal, or oral sex, and can be passed from an infected mother to her baby during a vaginal childbirth.  A man does not have to ejaculate to spread the infection. It is not possible to become infected with chlamydia by touching an object like a toilet seat. 

The risk of getting chlamydia is greater if you have a new sexual partner, more than one sexual partner, or if you have had chlamydia before.


Chlamydia infections can cause mild to severe symptoms. However, up to 50% of women with a chlamydia infection have no symptoms and do not know that they are infected.  This means that it is easy to spread the infection without ever knowing you are infected.

If left untreated, Chlamydia can cause serious reproductive and other health problems with both short-term and long-term consequences. Fortunately, most Chlamydia infections can be cured with antibiotics.

The most common symptoms for women include vaginal discharge, abnormal vaginal bleeding, abdominal pain, pain during sex or pain with urination. 

Chlamydia Diagnosis & Screening

Diagnostic tests include looking at samples of the discharge under a microscope, a swab from the cervix (women) or urethra (men) for a culture, or sending urine to a laboratory to identify the disease-causing bacteria and determine if you are infected. 

Chlamydia Prevention

The most effective way to prevent Chlamydia is to avoid sexual intercourse. Because this is not practical for most people, the following tips are recommended:

  • Use latex condoms when having sexual intercourse
  • Discuss testing for sexually transmitted infections with your healthcare provider. If you are in a long-term relationship and neither of you has sexual contact with anyone else, you have a lower risk of sexually transmitted infection
  • Do not have sexual contact with anyone who has symptoms of an STD, (abnormal discharge, pain or burning with urination, or a genital rash or sore) or who may have been exposed to an STD.  See your healthcare provider if you have any symptoms of chlamydia or another infection
  • Get tested!  Have sexual partners and yourself tested before having sexual relations
  • Be sure infected sexual partners have completed treatment before sexual contact.  Up to one-fourth of sexual partners will be re-infected because the partner wasn't treated

More Information

Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

You can also visit the Centers for Disease Control and Prevention at