Causes of Non-Specific Urethritis

Non-Specific Urethritis is often referred to as either NSU or NGU (standing for non-gonococcal urethritis). The condition can have unpleasant symptoms for men and lead to serious medical consequences in women, which is why its diagnosis and treatment is so important. In this article we look at the potential causes of non-specific urethritis.

Infectious causes of NSU

Sexually transmitted infections are thought to be one of the major causes of non-specific urethritis, particularly amongst men. In cases where STIs are responsible for the illness, your diagnosing physician will have been unable to detect which specific infection is responsible for the inflammation of the urethra involved in urethritis, this lack of a specific causative effect of the condition is what causes urethritis to be classed as non-specific.


Chlamydia is a relatively common sexually transmitted infection which is thought to cause at least half of all cases of non-specific urethritis in men, and about 40% in women. Chlamydia is a bacterial infection transmitted through any unprotected sex, including anal and oral intercourse. The bacteria responsible is called Chlamydia trachomatis, and infection with this bacteria can, if left untreated, cause more serious medical issues as well as urethritis.

This is why the practice of safe sex is an important method of avoiding NSU, and why you should have yourself tested for the condition if you or either a former or current partner are diagnosed with chlamydia.

Other bacteria and microorganisms can also potentially cause non-specific urethritis, and these can often be found living harmlessly in other parts of the body. Our throats, rectums, mouths, and digestive tract are rich in harmless bacteria which can cause urethritis should they come into contact with the urethra. In most cases exposure to these otherwise safe bacteria occurs through sexual intercourse.

Relatively common infections and infectious agents causing NSU here in the UK include bacteria like Mycoplasma, parasites like Trichomonas Vaginalis, and viruses like herpes which are responsible for herpes and cold sores. In these cases, as with chlamydia, it is important to be tested so that your doctor can provide you with any necessary treatment.

Non-infectious NSU

While infections may be one of the primary causes of non-specific urethritis, there are many examples of the condition being caused by injury or exposure to irritants. In these cases contact with a foreign object causes the urethra to become inflamed, and as this structure is responsible for the transport of urine from the bladder and out of the body, also causes the characteristic painful urination experienced by men suffering from NSU.

Inflammation is one of the body’s natural responses to foreign bodies and trauma, and while it can be painful and cause unpleasant effects, its purpose is important. Your body triggers inflammation when exposed to injury or a potentially harmful substance, and in doing so, isolates the affected site so as to better launch an immune response against it and to prevent the spread of potentially harmful substances or organisms to the rest of the body. In NSU, this inflammation restricts the size of the urethra and results in the painful expulsion of urine in men.

Irritants that can cause NSU are largely chemical products like certain soaps, spermicides, oils, lubricants, or deodorants. It is important to handle any such substance with care when near your genitals, and unless you are sure about the safety of the substance in question, you should not apply it to your penis.

NSU can also be caused by trauma to the urethra triggered by overly vigorous sexual activity. This includes both intercourse with a partner and masturbation, either of which can damage the urethra if performed unsafely.

A number of NSU cases are caused by the insertion of a material into the urethra. A relatively common example of NSU as a consequence of this is where catheters are inserted into the urethra. A catheter is essentially a bag into which urine can flow where a person is facing difficulties with bladder control or access to urinary facilities (e.g. because of movement issues or when bedbound for surgery). The application of a catheter involves inserting a lubricated tube into the urethra to access the bladder, and in some cases this process can damage the urethra and trigger an inflammatory leading to NSU.

Regardless of cause, a diagnosis of NSU is usually a good thing as it means your doctor can start administering the necessary treatment. Understanding why NSU has been caused influences treatment choices in some cases of course, for example NSU caused by an infection can be cleared up by addressing that underlying infection, which is why it is important that the necessary tests and patient history are provided by and to your doctor respectively.

« Symptoms of Non-Specific Urethritis Prognosis of Non-Specific Urethritis »