Sex

Chlamydia

Common bacterial sexually transmitted infection, treatable if caught, if not it can cause complications such as pelvic inflammatory disease in women, leading to infertility.

Look for a white-ish discharge from the penis, which often stains underwear, a burning pain when going to the loo and possibly swelling in the eyes. Many women have no symptoms at all, though may experience an increase in vaginal discharge, irregular menstrual cycles, stomach pain, wanting to go to the loo more frequently, pain on passing urine and during sex, and swelling in the eyes.

Treatment: Visit an STD or GUM clinic or your GP for diagnosis and a course of antibiotics.