Endocrine
The drug may cause adrenal insufficiency so the level of the adrenocortical hormones should be monitored while taking it. Oral ketoconazole at a dosage range of 400 to 2,000 mg/day has been found to result in a rate of gynecomastia of 21%. Liver
In July 2013, the U.S. Food and Drug Administration (FDA) issued a warning that taking ketoconazole by mouth can cause severe liver injuries and adrenal gland problems: adrenal insufficiency and worsening of other related to the gland conditions. It recommends oral tablets should not be a first-line treatment for any fungal infection. It should be used for the treatment of certain fungal infections, known as endemic mycoses, only when alternative antifungal therapies are not available or tolerated. As contraindication it should not be used in people with acute or chronic liver disease. Hypersensitivity
Anaphylaxis after the first dose may occur. Other cases of hypersensitivity include urticaria. Topical formulations
The topical formulations have not been associated with liver damage, adrenal problems, or drug interactions. These formulations include creams, shampoos, foams, and gels applied to the skin, unlike the ketoconazole tablets, which are taken by mouth. Pregnancy
Ketoconazole is categorized as pregnancy category C in the US. Research in animals has shown it to cause teratogenesis when administered in high doses. A subsequent trial in Europe failed to show a risk to infants of mothers receiving ketoconazole. Overdose
In the event of an overdose of oral ketoconazole, treatment should be supportive and based on symptoms. Activated charcoal may be administered within the first hour following overdose of oral ketoconazole.
This is in part due to the large variety of organisms living in the urinary tract. Ureaplasma urealyticum and Mycoplasma genitalium are some of the culprits. NGU is also associated with reactive arthritis, in which the triad of arthritis, conjunctivitis, and urethritis is seen. Bacterial
The most common bacterial cause of NGU is Chlamydia trachomatis, but it can also be caused by Ureaplasma urealyticum, Haemophilus vaginalis, Mycoplasma genitalium, Mycoplasma hominis, Neisseria meningitidis, Gardnerella vaginalis, Acinetobacter lwoffii, Acinetobacter calcoaceticus,  and E.coli. Viral
Herpes simplex virus, Adenovirus,
Cytomegalovirus

Fungi
Candida Albicans

Parasitic
Parasitic causes include Trichomonas vaginalis (rare). Noninfectious
Urethritis can be caused by mechanical injury (from a urinary catheter or a cystoscope), or by an irritating chemical (antiseptics or some spermicides). Diagnosis
It has been easy to test for the presence of gonorrhea by viewing a Gram stain of the urethral discharge under a microscope: The causative organism is distinctive in appearance; however, this works only with men because other non-pathogenic gram-negative microbes are present as normal flora of the vagina in women. Thus, one of the major causes of urethritis can be identified (in men) by a simple common test, and the distinction between gonococcal and non-gonococcal urethritis arose for this reason. Non-gonococcal urethritis (NGU) is diagnosed if a person with urethritis has no signs of gonorrhea bacteria on laboratory tests. The most frequent cause of NGU (23%-55% of cases) is C. trachomatis.