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Health Information Center


  • Cynthia M. Johnson, MA
Publication Type:




Chlamydia is a common sexually transmitted infection (STI).


Bacteria from an infected sex partner causes the infection. This can happen during oral, genital, or anal sex.

Risk Factors

Chlamydia is most common in people under 24 years of age. Other things that may raise the risk are:

  • Being sexually active
  • Prior STIs
  • Having a new sex partner
  • Having more than one sex partner
  • Having a partner with an STI
  • Having sex without a condom


Most people do not have symptoms.

In men, symptoms may be:

  • Pain when passing urine (pee)
  • Pus exiting the penis
  • Scrotal pain or swelling

In women, symptoms may be:

  • A change in vaginal discharge
  • Pain or bleeding during sex or between periods
  • Belly pain
  • Vaginal redness or pain
  • Pain when passing urine
Male Genitourinary System.

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Female Reproductive System Organs.

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The doctor will ask about symptoms and past health. A physical exam will be done. Tests for cause of the infection may be done with:

  • A swab of the penis, cervix, throat, or rectum
  • Urine tests


Antibiotics are used to treat the infection. Sexual partners should also be treated or the infection will continue to recur.


The risk of chlamydia may be lowered by:

  • Abstaining from oral, anal, or genital sex.
  • Limiting sex to one partner
  • Using latex condoms during sex




  • Chlamydia. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/std/chlamydia/default.htm.
  • Chlamydia fact sheet. Office on Women's Health—US Department of Health and Human Services website. Available at: http://www.womenshealth.gov/publications/our-publications/fact-sheet/chlamydia.html.
  • Chlamydia genital infection. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/chlamydia-genital-infection.
  • Sexually transmitted infections treatment guidelines, 2021. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/std/treatment-guidelines/default.htm.


  • Beverly Siegal, MD, FACOG
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.