Chlamydia is a sexually transmitted infection caused by a bacteria called 'Chlamydia trachomatis'. It affects both men and women, and it's spread by having unprotected vaginal, anal or oral sex with a person who has the infection.
Most people who have chlamydia don't notice any symptoms and so they don't know they have it. Research suggests that 50% of men and 70-80% of women don't get symptoms at all with a chlamydia infection.
Testing for chlamydia is done with a urine test for men or a women have a urine test or a swab taken from the cervix or vagina. You don't always have to have a physical examination by a doctor.
Chlamydia is treated with antibiotics. If it isn't treated, the infection can sometimes spread to other parts of your body and lead to serious long-term health problems such as pelvic inflammatory disease and infertility (not being able to have children).
You can help prevent being infected with chlamydia (and other sexually transmitted infections) by practising safe sex. This means using a condom when you have vaginal or anal sex and using a condom or dental dam for oral sex.
Check your symptoms with healthdirect's Symptom Checker to get advice on when to seek medical attention.
Expert advice on chlamydia - video
Last reviewed: July 2017