Causes and risk factors
Chlamydia is usually passed from one person to another during vaginal, oral or anal sex, or by sharing sex toys. It can live inside cells of the cervix, urethra, rectum and sometimes in the throat and eyes.
Chlamydia can also be passed from a pregnant woman to her baby.
Chlamydia is often referred to as the ‘silent infection’, as most men and women don’t have any obvious signs or symptoms, or they’re so mild they’re not noticed.
Symptoms can appear one to three weeks after you’ve come into contact with chlamydia, or many months later, or not until the infection spreads to other parts of your body.
Women might notice:
Unusual vaginal discharge.
Bleeding between periods or during or after sex.
Pain with sex or when passing urine.
Lower abdominal pain.
Men might notice:
White/cloudy, watery discharge from the tip of the penis.
Pain when passing urine or painful testicles.
If the infection is in the eye or rectum, you may experience discomfort, pain or discharge.
Tell your doctor or nurse if you’re pregnant, or think you might be, or you’re breastfeeding – this might affect the type of antibiotic you’re given. The antibiotics used to treat chlamydia interact with the combined oral contraceptive pill and the contraceptive patch, making them less effective, so check this with the doctor or nurse.
To avoid reinfection, any sexual partners should be treated too. Every time you have a new sexual partner you need to be tested. If complications occur, another treatment might be needed.
Without treatment, the infection can spread to other parts of the body causing damage and long-term health problems, including infertility.
In women, chlamydia can cause pelvic inflammatory disease. This can lead to:
Ectopic pregnancy (when a pregnancy develops outside the womb, usually in the fallopian tube).
Blocked fallopian tubes (the tubes that carry the egg from ovary to womb).
Long-term pelvic pain.
In men, chlamydia can lead to painful infection in the testicles and possibly reduced fertility.
Rarely, chlamydia can lead to inflammation of the joints in both men and women. This is known as reactive arthritis. When this involves the urethra and the eyes, it is known as Reiter’s syndrom.