If left untreated, chlamydia can lead to serious reproductive and other health problems with both short- and long-term consequences. Like symptoms of the disease itself, symptoms of the damage chlamydia causes are often “silent.” Complications from untreated chlamydia include:

• Pelvic inflammatory disease (PID). Chlamydia can spread into the uterus or fallopian tubes and cause PID (an infection of the uterus, fallopian tubes and other reproductive organs). This happens in up to 40 percent of women with untreated chlamydia. Although it may cause no signs or symptoms, PID can damage the fallopian tubes, ovaries and uterus, including the cervix. Untreated PID can lead to abscesses in the fallopian tubes and ovaries. The infection can cause scarring that may lead to infertility. PID affects up to 1 million women in the United States and half of all cases may be due to an untreated chlamydial infection.
  
  
• Epididymitis. The epididymis is the tube that transports the sperm from the testicles. In rare cases, chlamydia bacteria can infect the epididymis and cause it to become inflamed and painful. This condition is called epididymitis and can lead to infertility.
  
  
• Infertility. The inability to become pregnant after a year of continuous attempts. In women, a chlamydia infection can scar the fallopian tubes, preventing eggs from being fertilized. In men, chlamydia may infect the epididymis, leading to infertility.
  
  
• An ectopic or tubal pregnancy. In this medical condition, a fertilized egg starts developing outside the uterus, usually in the fallopian tube but sometimes in the cervix, ovary or abdomen. The embryo must be removed to prevent rupture of internal organs.
  
  
• Human immunodeficiency virus (HIV). Men and women infected with chlamydia are more likely to get HIV if exposed to the virus. The reason for the increased risk is that chlamydia causes a spike in the number of leukocytes (immune system cells) at the site of infection to help fight the infection. However, if exposed to HIV, it can infect these leukocytes.
  
  
• Reiter’s syndrome. Rarely, genital chlamydial infection may cause Reiter’s syndrome. This involves arthritis (inflammation of the joints) that can be accompanied by skin lesions (abnormal tissue) and inflammation of the eye and urethra (the tube that carries urine from the bladder to the outside of the body).