Urine Discoloration Associated With Metronidazole: A Rare Occurrence

Area of Science:

• Pharmacology
• Infectious Diseases
• Clinical Medicine

Background:

• Clostridium difficile infection (CDI) is a significant cause of antibiotic-associated diarrhea.
• Metronidazole is a common treatment for CDI, particularly in non-severe cases.
• Drug-induced side effects can impact patient adherence and require clinical awareness.

Purpose of the Study:

• To document a case of metronidazole-induced urine discoloration in a patient with CDI.
• To highlight a poorly reported but known adverse effect of metronidazole therapy.
• To inform clinicians about this benign side effect and its management.

Main Methods:

• Case report of a 52-year-old male patient with CDI.
• Administration of metronidazole for treatment of CDI.
• Observation of urine color changes correlated with metronidazole intake and cessation.
• Exclusion of other potential causes of urine discoloration (hemolysis, rhabdomyolysis).
• Causality assessment using the Naranjo probability scale.

Main Results:

• The patient developed cola-colored urine during metronidazole treatment for CDI.
• Urine color normalized upon temporary discontinuation of metronidazole.
• Urine discoloration recurred upon restarting metronidazole.
• No other adverse clinical effects were observed.
• Naranjo scale indicated probable causality between metronidazole and urine discoloration.

Conclusions:

• Metronidazole can cause urine discoloration as a benign side effect.
• Clinicians should be aware of this potential reaction to metronidazole.
• Patient reassurance is important as this side effect has no clinically relevant adverse outcomes.