There are many different causes. Some, but not all, are passed on through having sex. If you have non-specific urethritis there may be more than one cause, and in some men a cause is never identified.
If you have signs of inflammation in your urethra it is common to be told you have non-specific urethritis straightaway, before the cause is known. You will probably be tested for sexually transmitted or possibly urinary tract infections to try to find out what the cause of the inflammation is. You may have to wait for these results.
Causes of non-specific urethritis include:
Sexually transmitted infections
Chlamydia is a common cause of non-specific urethritis.
Genital 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. 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.
Damage to the urethra
This can be caused by friction during vigorous sex or masturbation, or inserting objects into the urethra. Frequently inspecting or squeezing your urethra can also irritate it and cause inflammation – some men do this if they have recently had an infection or they are worried they might have one.
Applying liquids such as tea tree oil, antiseptic or disinfectant or using medicated or highly perfumed shower gels can cause inflammation.
Sensitivity or irritation
Rarely, inflammation can occur if your skin is very sensitive to chemicals, such as those in latex (in condoms, for example), spermicide or soap.