Chlamydia is the most common bacterial STI in the UK. It often doesn't cause any symptoms, but it can lead to serious health problems. Chlamydia can spread to the uterus and fallopian tubes and cause pelvic inflammatory disease (PID). PID, if left untreated, can lead to infertility, chronic pelvic pain, and dangerous complications in pregnancy.
The symptoms of chlamydia and gonorrhoea are similar. They include burning when you pass urine and an abnormal and discoloured discharge from the penis or vagina. Only about half of women infected with gonorrhoea have symptoms and they are often mild. A higher proportion of men (up to nine in ten) will experience symptoms, and they are likely to be more pronounced.