Overview

Chlamydia (kluh-MID-e-uh) trachomatis (truh-KOH-muh-tis) is a common sexually transmitted infection (STI) caused by bacteria. You might not know you have chlamydia because many people don't have signs or symptoms, such as genital pain and discharge from the vagina or penis.

Chlamydia trachomatis affects mostly young women, but it can occur in both men and women and in all age groups. It's not difficult to treat, but if left untreated it can lead to more-serious health problems.