Clinical significance of rare and benign side effects: propofol and green urine.

A 55-year-old man requiring airway protection for esophagogastroduodenoscopy was sedated with propofol. On the third day of propofol infusion his urine was dark green. Although he was afebrile and his white blood cell count was within normal limits, the green urine was suspected to be of infectious etiology. Laboratory tests were ordered and broad-spectrum antibiotics were considered. Antibiotics were avoided when propofol was recognized as a rare and benign potential cause of the green urine. Earlier recognition of this side effect may have averted unnecessary laboratory monitoring. Prompt recognition of such side effects is important in limiting medical expenditures, inordinate drug exposure, and distress among patients and clinicians.