Non-specific urethritis (NSU) is a term initially provided for symptoms of cystitis that have no apparent cause. It was assumed that NSU was caused by viruses but in the last two decades the two organisms Trichomonas and Chlamydia have been thought to be the culprits.
Most commonly these create vaginal infections that are often asymptomatic. At worst they may ascend into the uterus and cause salpingitis (inflammation of the Fallopian tube; see Salpingitis) but they frequently trigger urethritis.
Non-specific urethritis may also be a pseudonym for honeymoon cystitis created by the friction of intercourse. In my opinion the true definition is somewhat blurred.
See Cystitis for specific symptomatic treatment.
If Trichomonas or Chlamydia are isolated, treatment of the vaginal vault is recommended. Single or combined treatments using pessaries of Tea Tree, Lavender, Hydrastis and Calendula may be beneficial if used morning and night.