What Is Chlamydia?

You may have heard of chlamydia, but many people are not sure what it is. Chlamydia (klah MIH dee ah) is an infection caused by a kind of bacteria that is passed during sexual contact. It is the most common sexually transmitted bacterial infection in the United States. About three million American women and men become infected with chlamydia every year. It is especially common among women and men under 25.

Chlamydia is

• five times as common as gonorrhea
• more than 30 times as common as syphilis

Chlamydia can infect the penis, vagina, cervix, anus, urethra, eye, or throat.

What Are the Symptoms of Chlamydia?

Usually, chlamydia has no symptoms. Most people are not aware that they have the infection — especially women.

• Three out of four women with chlamydia have no chlamydia symptoms.
• Half of men with chlamydia have no chlamydia symptoms.

If you do get chlamydia symptoms, they may begin in as little as 5 to 10 days after you got the infection.

When men have symptoms, they may experience

• pain or a burning feeling while urinating
• pus or watery or milky discharge from the penis
• swollen or tender testicles
• swelling around the anus

In both women and men, chlamydia may cause the anus to itch and bleed. It can also result in a discharge and diarrhea. If chlamydia infects the eyes, it may cause redness, itching, and a discharge. If chlamydia infects the throat, it may cause soreness.

Chlamydia symptoms may only appear in the morning and may be mild, especially for men. That's why many people do not realize they have an infection. If you or your partner has any of the symptoms listed above, get checked by a health care provider. This is especially important if you are pregnant.