Chlamydia (pronounced klah-MID-dee-uh) is the most common sexually transmitted infection in the United States . There are about four million cases of chlamydia in the United States every year.
Chlamydia and gonorrhea (another sexually transmitted infection) cause similar signs and symptoms, including discharge from the penis or vagina and pain with urination. However, chlamydia sometimes causes no symptoms. In addition, chlamydia can cause serious long-term complications in women who are not treated. Fortunately, chlamydia is curable with antibiotic treatment.