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warnings
Phenazopyridine hydrochloride is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity in experimental animals (IARC 1980, 1982, 1987, NCI 1978). When administered in the diet, Phenazopyridine hydrochloride increased the incidences of hepatocellular adenomas and carcinomas in female mice and adenomas and adenocarcinomas of the colon and rectum in rats of both sexes. There is inadequate evidence for the carcinogenicity of Phenazopyridine hydrochloride in humans (TARC 1987). In one limited epidemiological study, no significant excess of any cancer was observed among 2,214 patients who received Phenazopyridine hydrochloride and were followed for a minimum of 3 years.
The following adverse events have been reported: CNS: headache. Gastrointestinal: nausea, vomiting and diarrhea. Dermatologic and Hypersensitivity: rash, pruritus, discoloration, anaphylactoid-like reaction and hypersensitivity hepatitis. Hematologic: methemoglobinemia, hemolytic anemia, potential hemolytic agent in G-6-PD deficiency, sulfhemoglobinemia. Other: visual disturbances, renal and hepatic toxicity usually associated with overdose, renal calculi, jaundice, discoloration of body fluids and aseptic meningitis.