- This is the most common STD in the UK. Occurring in about 1 in 12 individuals between the ages of 16-24. Symptoms differ between men, women and children. Women will often experience non-specific symptoms such as cystitis, change in vaginal discharge & mild lower abdominal pain. If left untreated it can lead to pelvic pain, pain during sex and occasionally bleeding between periods. The infection can also spread to the womb and fallopian tubes causing pelvic inflammatory disease and can also be a major cause of miscarriage, ectopic pregnancy and infertility. For men, about half will experience symptoms such as urethral discharge from the penis, inflammation of the tube leading from the bladder to the tip of the penis or the tube leading from the testes to the penis, which can cause infertility. The infection can also cause an uncommon condition called Reiter's condition which affects the eyes and joints. Symptoms usually occur 7-21 days after infection.