Chlamydia is the most common STI in the UK. It is easily passed on during sex. Most people don't experience any symptoms, so they are unaware they're infected.
In women, chlamydia can cause pain or a burning sensation when urinating, a vaginal discharge, pain in the lower abdomen during or after sex, and bleeding during or after sex or between periods.
In men, chlamydia can cause pain or a burning sensation when urinating, a discharge from the tip of the penis, and pain or tenderness in the testicles.
It is also possible to have a chlamydia infection in your rectum (bottom), throat or eyes
Diagnosing chlamydia is done with a urine test or by taking a swab of the affected area. The infection is easily treated with antibiotics but can lead to serious long-term health problems if left untreated, including infertility.