Sexually transmitted infections
Chlamydia is a common cause of non-specific urethritis. Up to 50 per cent of men who have inflammation of the urethra are found to have chlamydia.
Herpes and trichomonas vaginalis are less common causes.
Tiny organisms called mycoplasma genitalium and ureaplasma urealyticum can live in the body without causing symptoms but sometimes they multiply quickly, leading to inflammation of the urethra. Being ill or stressed could cause this to happen. Up to 10 per cent of cases of non-specific urethritis are thought to be caused by ureaplasma urealyticum, and up to 25 per cent of cases by mycoplasma genitalium. It is thought these organisms may be transmitted sexually.
Some bacteria that live in the rectum and the mouth and throat can be passed on during sex and cause inflammation.
Bacteria that cause infection in the urinary tract (kidneys, bladder and urethra) or the prostate gland can lead to inflammation of the urethra.
A vaginal infection in your partner, such as thrush or bacterial vaginosis, may trigger non-specific urethritis in you.