Phenazopyridine is a medication which, when excreted by the kidneys into the urine, has a local analgesic effect on the urinary tract.

It is sometimes used in conjunction with an antibiotic (usually norfloxacin) or other anti-infective medication at the beginning of treatment to help provide immediate symptomatic relief.

This is due to a depressed excretion via the kidneys causing a buildup of the medication in the skin, and normally indicates a need to discontinue usage.

[4] Other such side effects include fever, confusion, shortness of breath, skin rash, and swelling of the face, fingers, feet, or legs.

[7] Phenazopyridine should be avoided by people with glucose-6-phosphate dehydrogenase deficiency,[4][8][9][10] because it can cause hemolysis (destruction of red blood cells) due to oxidative stress.

[17][18] Other azo dyes, which were previously used in textiles, printing, and plastic manufacturing, have been implicated as carcinogens that can cause bladder cancer.

[19] While phenazopyridine has never been shown to cause cancer in humans, evidence from animal models suggests that it is potentially carcinogenic.

[4][20] This medication has shown no adverse events in animal models, but no human trials have been conducted.