Chlamydia is a sexually transmitted disease caused by the bacteria Chlamydia trachomatis.

Causes, incidence, and risk factors

Chlamydia infection is caused by the organism Chlamydia trachomatis. It is the most common sexually transmitted disease in the United States. Sexually active individuals and individuals with multiple partners are at highest risk.

Chlamydia may be acquired jointly with gonorrhea and/or syphilis, so individuals with one sexually transmitted disease must be screened for other sexually transmitted diseases as well. Untreated chlamydia can lead to pelvic infection and infertility.

In men, chlamydia may produce symptoms similar to those of gonorrhea (discharge from penis or rectum, burning on urination or defecation), and can also cause epididymitis and orchitis. However, up to 25% of infected men may have no symptoms.

Chlamydia (female): only approximately 30% of women will have symptoms due to chlamydia - hence screening sexually active women for chlamydia is necessary to diagnose and treat asymptomatic women in order to decrease the risk of developing complications. Women who do have symptoms may note vaginal discharge, burning on urination, or abdominal pain.

Untreated infection may lead to pelvic inflammatory disease (PID), which can cause scarring of the fallopian tubes and result in infertility. Tubal scarring also increases the likelihood of an ectopic pregnancy (tubal pregnancy).

If a women is infected with chlamydia while pregnant, the infection can cause premature labor and delivery. In addition, the infant may develop chlamydial conjunctivitis (eye infection) and chlamydial pneumonia.


  • burning sensation during urination  
  • discharge from the penis  
  • testicular tenderness or pain  
  • rectal discharge or pain


  • vaginal discharge  
  • burning sensation during urination  
  • sexual intercourse, painful  
  • symptoms of PID, salpingitis, perihepatitis (liver inflammation similar to hepatitis) - see the individual diseases for symptoms  
  • rectal pain or discharge

Signs and tests

The diagnosis of chlamydia infection involves sampling of the urethral discharge in males or cervical secretions in females. If an individual engages in anal sexual contact, samples from the rectum may also be needed. The sample is sent for a fluorescent or monoclonal antibody test, DNA probe test or cell culture. Some of these tests may also be performed on urine samples.


The mainstay of therapy for chlamydia includes appropriate antibiotic treatment - these include: tetracyclines, azithromycin or erythromycin. All sexual contacts should be screened for chlamydia.

Sexual partners must be treated to prevent passing the infection back and forth. There is no significant immunity following the infection and a person may become repeatedly infected.

A follow-up evaluation may be done in 4 weeks to determine if the infection has been cured.

Expectations (prognosis)
Early antibiotic treatment is extremely successful and may prevent the development of long-term complications. Untreated infection, however, may lead to PID, scarring and ultimately infertility.


  • pelvic inflammatory disease (PID)  
  • salpingitis  
  • infertility  
  • ectopic pregnancy

Calling your health care provider

Call your health care provider if you have any of the symptoms associated with chlamydial infection.

Because a significant proportion of individuals with chlamydia may not have any symptoms, sexually active adults (in particular women with new or multiple partners) should be screened periodically for chlamydia.

Safe sexual practices and consistent condom use are important prevention measures to help decrease infection with chlamydia. In addition, sexually active individuals (in particular women with new or multiple sexual partners) should be periodically screened for chlamydia.

Johns Hopkins patient information

Last revised: December 2, 2012
by Arthur A. Poghosian, M.D.

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