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.

[4] Phenazopyridine is prescribed for other cases requiring relief from irritation or discomfort during urination; for example, after the use of an in-dwelling Foley catheter, endoscopic (cystoscopy) procedures, or after urethral, prostate, or urinary bladder surgeries that may result in irritation of the epithelial lining of the urinary tract.

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.