Chlamydia
The sexually transmitted infection (STI) known as Chlamydia, is thought to be responsible for an estimated 43% of all cases of non-specific urethritis (NSU).
Chlamydia is caused by bacteria called Chlamydia trachomatis, which can be spread during unprotected sex, including anal and oral sex.
Other bacteria
Other bacteria that usually live harmlessly in the throat, mouth, or rectum can trigger the development of NSU, if they manage to find their way into the urethra. This can often occur during oral and anal sex.
Damage to the urethra
Damage to the urethra (the tube that urine passes through) can be a non-infectious cause of NSU, resulting in inflammation. The urethra can sometimes be damaged by vigorous sex, or masturbation, or by inserting an object into it.
Antiseptic liquids, such as liquid disinfectant, soap, or tea-tree oil, can also irritate the urethra and result in inflammation.
Viruses
Less commonly, some viruses, such as the herpes virus, can cause NSU in some men.
Bacteria
Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease and some others are good for you.
Urethra
The urethra is a tube that carries urine from the bladder to the outside of the body.
Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.
Antiseptic
Antiseptic is a substance that reduces the growth and development of germs.
