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What can untreated chlamydia turn into?

Chlamydia is a common sexually transmitted infection (STI) caused by the bacteria Chlamydia trachomatis. When left untreated, chlamydia can lead to serious health problems. Here’s an in-depth look at what untreated chlamydia can potentially develop into.

Pelvic Inflammatory Disease (PID)

One of the most common complications of untreated chlamydia is pelvic inflammatory disease (PID). PID affects the female reproductive organs including the uterus, fallopian tubes and ovaries. According to the Centers for Disease Control and Prevention (CDC), 10-15% of women with untreated chlamydia will develop PID.

The chlamydia bacteria can spread from the cervix to the uterus, fallopian tubes and other pelvic organs, causing infection and inflammation. PID symptoms may include:

  • Lower abdominal pain
  • Fever
  • Unusual vaginal discharge
  • Pain during sex
  • Painful periods
  • Pain during urination or bowel movements

PID requires prompt antibiotic treatment. Without treatment, PID can cause permanent damage leading to chronic pelvic pain, infertility and increased risk of ectopic pregnancy.


One of the major risks associated with untreated chlamydia that leads to PID is infertility or inability to get pregnant. According to the CDC, about 10-15% of women with chlamydia will develop PID, and up to 20% of those cases may become infertile.

When chlamydia spreads to the fallopian tubes, it can cause scarring and tissue damage. The tubes may become partially or entirely blocked. This can prevent fertilization of the egg by sperm or block the passage of the fertilized egg into the uterus.

Studies suggest that the fertility of women decreases by about 10-20% after one PID episode and by up to 50% after two or more episodes. Infertility may be temporary or permanent.

Ectopic Pregnancy

Women with PID caused by chlamydia have a significantly higher risk of ectopic pregnancy. This is when the fertilized egg implants and grows outside of the uterus, usually in one of the fallopian tubes. Ectopic pregnancies are not viable and can be life-threatening.

Rates of ectopic pregnancy in women with a history of PID range from 9-18%, compared to 2% in the general population. Prompt treatment of chlamydia can help reduce the risk of ectopic pregnancy.

Chronic Pelvic Pain

PID associated with chlamydia can also lead to chronic or long-term pelvic pain. Between 15-40% of women with PID develop chronic pelvic pain that can be severe and debilitating. Pain may persist for months or years after the infection has cleared.

The underlying mechanisms are not fully understood but likely involve nerve damage and the formation of scar tissue and adhesions.


In men, untreated chlamydia infections can spread from the urethra to the epididymis causing epididymitis. The epididymis is a tube located at the back of the testicles that stores and transports sperm.

Symptoms of epididymitis may include:

  • Testicular pain and swelling
  • Fever
  • Pain during urination or ejaculation
  • Discharge from the penis

Without treatment, the infection can result in abscess formation, testicular atrophy and potential infertility. Prompt antibiotic treatment is important.


Like PID in women, epididymitis caused by chlamydia can also permanently damage the reproductive system in men leading to infertility. Studies indicate that about 20% of cases of epididymitis caused by chlamydia and other STIs result in infertility.

The underlying mechanism involves blockage of the epididymis and damage to sperm. Scarring from the infection prevents the proper maturation and transport of sperm needed for fertilization.


Chlamydia can also infect the rectum as a result of anal sex. This causes inflammation of the rectum known as proctitis. Symptoms include:

  • Rectal pain
  • Bleeding from the rectum
  • Pus or mucus discharge
  • Constipation or diarrhea

Proctitis increases the risk of acquiring and transmitting HIV if exposed. It can also spread the infection to the intestines. Rectal chlamydia is treated with oral or rectal antibiotics.

Reactive Arthritis

About 1-5% of men and women with untreated chlamydia develop a condition known as reactive arthritis, also called Reiter’s syndrome. This causes inflammation of the joints as well as eye and urinary tract irritation. It may develop up to 6 months after the initial chlamydia infection.

The triad of symptoms may include:

  • Inflammation of the urethra (urethritis) and eyes (conjunctivitis)
  • Joint pain or arthritis
  • Skin lesions such as pustules or patches

Reactive arthritis often resolves on its own but antibiotics may be used in some cases. Prompt chlamydia treatment helps reduce the risk of this complication developing.

Increased Risk of HIV

Having an untreated chlamydia infection can increase both the risk of acquiring and transmitting HIV, the virus that causes AIDS. According to some studies, people with chlamydia are up to 5 times more likely to contract HIV if exposed.

Chlamydia causes inflammation and damage to the mucous membranes of the genital tract. This makes it easier for HIV to enter the body. The chlamydia bacteria also activates immune cells in the genital area which HIV can then infect.

By causing complications like PID and proctitis, chlamydia can further increase susceptibility to HIV in women and men who have sex with men.

Ophthalmia Neonatorum

Pregnant women with untreated chlamydia can pass the infection on to their newborn during vaginal delivery. This can cause an eye infection in the baby called ophthalmia neonatorum. Symptoms usually develop within 5-12 days of birth. They include:

  • Redness
  • Swelling
  • Discharge
  • Crusting of eyelids

If not treated promptly, it can lead to scarring of the cornea and permanent vision damage. Oral antibiotics are used to treat eye infections in newborns caused by chlamydia.

Pneumonia and Conjunctivitis

Chlamydia pneumonia and chlamydia conjunctivitis are less common conditions that can result from untreated infections.

Chlamydia pneumonia causes respiratory symptoms including cough, shortness of breath and fever. It is treated with antibiotics.

Chlamydia conjunctivitis causes redness, irritation and discharge from the eyes. Oral and topical antibiotics are used for treatment.


The best way to prevent complications of untreated chlamydia is to get tested and treated promptly. Annual screening is recommended for sexually active women under 25. Older women and men who have sex with men should also get regular screening.

Using condoms correctly every time you have sex can also reduce the risk of contracting chlamydia. Limiting numbers of sexual partners helps too.

If you test positive for chlamydia, complete your full course of antibiotics. Also, advise your partners to get tested and treated to prevent reinfection.

With early diagnosis and treatment, chlamydia is easy to cure and long-term health issues can be avoided.


In summary, untreated chlamydia has the potential to progress into several serious health conditions. In women, this includes PID, infertility, chronic pelvic pain, and ectopic pregnancy. In men, epididymitis and infertility are main risks. Other complications include reactive arthritis and increased vulnerability to HIV.

Pregnant women can transmit chlamydia to their babies during birth, causing eye infections and pneumonia. Getting regular chlamydia screenings and promptly treating any infections found is crucial for preventing complications and transmission.

Chlamydia is treatable with antibiotics. However, the damage done by untreated infections can sometimes be permanent. This underscores the importance of early testing and treatment, especially for sexually active young women.