What is chlamydia?

Chlamydia trachomatis (C. trachomatis) is a bacterium, and C.trachomatis infection is the most common sexually transmitted infection (STI). Both men and women can get chlamydia. When left untreated, chlamydia can cause:

  • Damage the sex organs.
  • Cause sterility (the inability to have children).
  • Cause tubal pregnancies, which can lead to the death of the mother and child.
  • Cause premature births (giving birth too early).

Can I get chlamydia more than once?

Yes. In fact, repeat infections are very common in those who do not carefully protect themselves from infection.

What causes chlamydia?

The bacteria C. trachomatis causes infections. The infection is spread during sex or through intimate contact with the genitals or anus.

What are the symptoms of chlamydia?

In women

About half of the women with chlamydia do not have symptoms. When symptoms are present, they may include:

  • White, yellow or green discharge (fluid) from the vagina that may have a bad smell.
  • Bleeding between periods.
  • Itching or burning in or around the vagina.
  • Dull pain in the lower abdomen or pelvis.
  • Pain or burning when passing urine.
  • Painful periods.
  • Pain in the upper right side of the abdomen.
  • Pain, bleeding, or mucous discharge from the rectum.

In men

Most men have symptoms, although some do not. Symptoms include:

  • Clear or white discharge (fluid) from the penis.
  • Pain or burning when passing urine.
  • Pain and swelling around the testicles.

Last reviewed by a Cleveland Clinic medical professional on 04/14/2015.


  • Geisler WM, Stamm WE. Chapter 13. Genital Chlamydial Infections. In: Klausner JD, Hook EW, III. eds. CURRENT Diagnosis & Treatment of Sexually Transmitted Diseases. New York, NY: McGraw-Hill; 2007. library.ccf.org Accessed 5/4/2015.
  • Centers for Disease Control and Prevention. Chlamydia Accessed 5/4/2015.
  • Planned Parenthood. Chlamydia Accessed 5/4/2015.

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