Phenazopyridine - induced methaemoglobinaemia

The ability of redox drugs and chemicals to induce methaemoglobinaemia is well recognised. Phenazopyridine, a commonly used urinary analgesic, is one such drug which occasionally causes methaemoglobinaemia. Most cases have occurred following overdose, or in patients with impaired renal function (Cohen and Borasso, 1971; Nathan et al, 1977; Sand and Edelman, 1961; Greenberg and Wong, 1964; Crawford et al, 1951; Randazzo et al, 1975; Jeffery et al, 1982). 1982). We report a case of life-threatening methaemoglobinaemia due to phenazopyridine overdose, in a young woman who denied drug ingestion.