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Chlamydia trachomatis is a bacterium that can cause an STD. Chlamydia infection is very common among young adults and teenagers. However, many people do not know that they have chlamydia, because although they are infected they may not have any symptoms. About 75% of infected women and half of infected men have no symptoms of Chlamydia.

Chlamydia is transmitted through sexual contact (primarily vaginal or anal) with an infected person.

Risk Factors

The primary risk factors for chlamydia include:
• Engaging in sex without a male or female condom
• Having sex with more than one partner
• Being in a sexual relationship with someone who has multiple sex partners


The chance of becoming infected with chlamydia can be reduced by avoiding risky sexual behaviors.
To reduce your risk:
• Use latex or polyurethane condoms during sex
• Limit your number of sex partners


About 75% of women and 50% of men with chlamydia have no symptoms of infection.
In women, symptoms of chlamydia may include:
• An unusual vaginal discharge
• Bleeding after intercourse
• Bleeding between menstrual periods
• Abdominal or pelvic pain
In men, symptoms of chlamydia may include:
• Discharge from the penis
• Burning with urination
• Swollen and/or painful testicles

When left untreated, chlamydia can increase the risk of acquiring or transmitting HIV, the virus that causes AIDS.
In women, untreated chlamydia can spread into the pelvic area and infect the uterus, fallopian tubes, and ovaries–leading to pelvic inflammatory disease (PID). The symptoms of PID include:
• Abdominal pain
• Lower back pain
• Pain with intercourse
• Bleeding between periods
• Fever
PID can be a very serious condition and requires immediate medical care. It may cause permanent damage to the woman's reproductive organs and can lead to infertility, chronic pelvic pain, and an increased risk of ectopic pregnancy.
In men, untreated chlamydia can affect the testicles, leading to swelling and pain. Related complications can lead to infertility.


There are a variety of laboratory tests that can be used to diagnose chlamydia infection. Tests are done with either a urine sample or a sample obtained from a woman's cervix or a man's urethra, using a cotton swab.

Chlamydia can be easily treated and cured with antibiotics. It is important to make sure your sex partner(s) also receives treatment in order to prevent getting infected again. Avoid having sex while being treated to reduce the chances of getting the infection again or transmitting it to someone else.

Department of Public Health
Disease Control Branch
Health Administration Building
4065 County Circle Drive, Riverside, CA 92503
(951) 358-5107 | FAX 358-5446 | TDD 358-5124 | Email: