Chlamydia
Chlamydia is a bacterial infection caused by the bacterium Chlamydia trachomatis, primarily transmitted through sexual contact. It is one of the sexually transmitted diseases (STDs), also known as sexually transmitted infections (STIs).
In Italy, in 2023, there was a 21.4% increase in cases and a 35.7% increase in tests performed compared to 2021, with young people aged 15 to 24 being three times more affected than those over 24 (ISS data).
If left untreated, chlamydia can lead to serious complications in both women and men, making early diagnosis and preventive measures essential.
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On this page
- What Is Chlamydia?
- What Are the Symptoms of Chlamydia?
- How Do You Diagnose Chlamydia?
- How Do You Treat Chlamydia?
What Is Chlamydia?
Chlamydia is a bacterial infection of the urogenital tract, primarily transmitted through unprotected sexual intercourse – vaginal, anal, and oral. Vertical transmission from mother to child during pregnancy is also possible.
Among sexually transmitted diseases (STDs), chlamydia is one of the most widespread and affects women in particular. If diagnosed and treated promptly, it does not cause problems. However, if left untreated, the infection can spread and lead to serious complications, such as inflammation of the fallopian tubes or ovaries, reduced reproductive organ function, and an increased risk of infertility. Other possible consequences include reactive arthritis.
What Are the Symptoms of Chlamydia?
Chlamydia is often asymptomatic or causes mild, temporary symptoms that appear between one and three weeks after infection. For this reason, annual screening is recommended, especially for individuals who have unprotected sex or multiple partners.
When symptoms do occur, they vary depending on the site of infection.
In women:
- Burning or pain during urination and sexual intercourse.
- Abdominal or lower back pain.
- Mild fever.
- Abnormal vaginal discharge.
- Bleeding between menstrual cycles or after intercourse.
In men:
- Pain during urination.
- Pain and/or swelling in the testicles.
- Watery or purulent discharge from the penis.
In case of rectal infection (men and women):
- Rectal or anal pain.
- Anal discharge or bleeding.
In case of oral infection (rarer):
- Mouth pain.
- Sore throat with swelling.
- Ulcers inside or around the mouth.
How is chalmydia transmitted?
Chlamydia is primarily transmitted through unprotected vaginal and anal sexual intercourse. It can rarely spread through oral sex or from mother to newborn during childbirth.
How Do You Diagnose Chlamydia?
Chlamydia is diagnosed through specific tests, which may include a simple urine test or a vaginal, rectal, or throat swab – depending on the individual's symptoms, anatomy, and sexual history.
Anyone showing symptoms consistent with the infection or who may have been sexually exposed should undergo testing.
Routine screening is recommended for individuals who have occasional sexual encounters with different partners.
In Italy, screening is offered to pregnant women with identified risk factors during the first prenatal visit, with possible repetition in the third trimester if those risk factors persist.
How Do You Treat Chlamydia?
Chlamydia is effectively treated with antibiotic therapy. The type of antibiotic and duration of treatment depend on the severity of the infection and whether pregnancy is present. While the therapy eliminates the infection, it cannot reverse any damage already caused by the bacteria—making early intervention essential.
During treatment, it is important to abstain from sexual activity until one week after the first antibiotic dose and until symptoms have completely resolved. Additionally, all sexual partners from the past 60 days must be notified and tested.
Long-term problems caused by untreated chlamydia
If left untreated, chlamydia can lead to pelvic inflammatory disease in women, causing scarring in the fallopian tubes and increasing the risk of infertility or ectopic pregnancy.
In men, the infection can rarely result in infertility. Both sexes may develop liver complications or reactive arthritis.
Chlamydia can also be transmitted from mother to newborn during childbirth, posing risks such as pneumonia, eye infections, or low birth weight.
Experts recommend that individuals planning to have children undergo STI screening with their partner before conception.
How can chlamydia be prevented?
The risk of chlamydia can be significantly reduced by:
- Undergoing regular screenings in cases of casual sex or multiple partners.
- Practicing safe sex, including the use of barrier contraceptives and proper hygiene during and after intercourse.
When both partners test negative and do not engage in sexual activity outside the relationship, the risk of infection is zero.
It is essential to have open discussions with partners and your primary care physician about sexual and reproductive health, sharing your sexual history to make informed and responsible decisions.
Reviewed August 2025.