A big problem with chlamydia is that it often produces no symptoms, and if left undetected and untreated, complications can occur. People who have chlamydia can still transmit the infection, even if they don't have any symptoms themselves.
When symptoms do occur, they may not appear until several weeks after having sex with an infected person. Women with chlamydia might notice changes with their periods, bleeding or pain during or after sex, pain when urinating, cramping or pain in the lower abdomen, or changes to their vaginal discharge.
Women with untreated chlamydia are at risk of complications such as pelvic inflammatory disease (PID, in which one or more of the reproductive organs in the pelvis become inflamed); chronic pelvic pain; ectopic pregnancy (in which a pregnancy develops outside the uterus, such as in the fallopian tubes); and infertility, due to infection and scarring of the fallopian tubes.
Men with chlamydia are at risk of infections that can result in swollen and sore testicles, discharge from the urethra (the tube through which urination occurs), and difficulty urinating or pain when urinating.
Having oral sex or anal sex with someone who has the infection can result in infection of the throat or the rectum, causing pain and a discharge of pus or mucus.
Last reviewed: June 2017