Methemoglobinemia, muscle damage and renal failure complicating phenazopyridine overdose

A 19-year-old woman with no history of renal or hematologic dysfunction developed methemoglobinemia, muscle damage, rhabdomyolysis and severe acute renal failure after an overdose of phenazopyridine hydrochloride (pyridium). The methemoglobinemia reversed after 24 h, but the patient remained oliguric, with myalgia and increased muscle enzymes. The patient received supportive treatment and recovered completely after 3 weeks. Since phenazopyridine is a commonly used drug, the physician should be alert to these possible severe complications.