Phenazopyridine

Phenazopyridine is a painkiller (analgesic) available by prescription and over the counter, used to relieve pain and discomfort in the lower urinary tract. Phenazopyridine does not treat the cause of urinary tract symptoms, but provides temporary relief from irritation caused by medical procedures, surgery, urinary catheter, injury or infection.

Phenazopyridine is an azo dye with analgesic properties, but it is not clear how exactly it works. Phenazopyridine is excreted in the urine and is believed to act like a topical analgesic on the mucous lining of the urinary tract. Phenazopyridine is typically used for a maximum of two days with antimicrobial therapy to relieve symptoms before the antimicrobial drugs take effect.

• Do not use phenazopyridine in patients who:
  • Are hypersensitive to phenazopyridine or any of its components
  • Have impaired kidney function
• Limit use for a maximum of two days; discontinue phenazopyridine if symptoms continue after two days or adverse effects occur
• Phenazopyridine changes the urine color; may affect urinalysis based on spectrometry or color reactions
• Discontinue phenazopyridine if the skin or eye whites turn yellowish color; it is an indication of drug accumulation in tissue because of kidney failure; exercise particular caution in geriatric patients
• Use with caution in patients with G6PD deficiency, a genetic disorder that causes red blood cells to break down in response to certain medications, infections or other stresses; can lead to hemolytic anemia with chronic overdose of phenazopyridine
• Phenazopyridine use in patients with kidney disease can cause kidney failure, hemolytic anemia and methemoglobinemia, a condition with high levels of methemoglobin, a form of hemoglobin that does not release oxygen to the tissues effectively

Common side effects of phenazopyridine include:

• Fever
• Urine discoloration
• Rash
• Itching (pruritus)
• Headache
• Dizziness
• Nausea
• Vomiting
• Diarrhea
• Stomach cramps
• Elevated liver enzymes
• Liver inflammation (hepatitis)
• Jaundice
• High count of eosinophils (eosinophilia)
• Visual disturbances
• Contact lens discoloration
• Skin pigmentation

Severe side effects of phenazopyridine include:

• Anemia due to rapid destruction of red blood cells (hemolytic anemia)
• Methemoglobinemia
• Kidney stones (renal calculi)
• Damage to tubules in the kidney (renal tubular necrosis)
• Acute kidney failure
• Aseptic meningitis
• Serious allergic reactions (anaphylaxis-like)

This is not a complete list of all side effects or adverse reactions that may occur from the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may also report side effects or health problems to the FDA at 1-800-FDA-1088.

Tablets

• 95 mg
• 97.2 mg
• 100 mg
• 200 mg

Dysuria, Irritation of Lower Urinary Tract Mucosa

Adult:

• 100-200 mg orally after meals three times daily

Pediatric:

• Children under 6 years: Safety and efficacy not established
• Children 6-12 years: 12 mg/kg/day orally after meals, divided every 8 hours
• Children over 12 years: 100-200 mg orally after meals three times daily

Dosing considerations

• When used concomitantly with antibiotics for urinary tract infection (UTI), do not use for longer than 2 days
• Limit dosing in geriatric population due to decreased renal function

Administration

• Give after food/meals to minimize gastrointestinal (GI) side effects

• Overdose of phenazopyridine can cause methemoglobinemia, which can be reversed by administration of intravenous (IV) methylene blue, 1 to 2 mg/kg/dose given as a 1% solution as needed.
• Overdose may also be toxic to the kidneys and liver, and the treatment is symptomatic and supportive care. In case of overdose, seek medical help immediately or contact Poison Control.

Inform your doctor of all medications you are currently taking, who can advise you on any possible drug interactions. Never begin taking, suddenly discontinue, or change the dosage of any medication without your doctor’s recommendation.

• Phenazopyridine has no known severe interactions with other drugs.
• Phenazopyridine has no known serious interactions with other drugs.
• Moderate interactions of phenazopyridine include:
  • prilocaine
• Phenazopyridine has no known mild interactions with other drugs.

The drug interactions listed above are not all of the possible interactions or adverse effects. For more information on drug interactions, visit the RxList Drug Interaction Checker.

It is important to always tell your doctor, pharmacist, or health care provider of all prescription and over-the-counter medications you use, as well as the dosage for each, and keep a list of the information. Check with your doctor or health care provider if you have any questions about the medication.

• Animal reproduction studies do not reveal evidence of fetal harm from maternal phenazopyridine use during pregnancy. There are no adequate and well-controlled studies of phenazopyridine use in pregnant women; use only if the benefits outweigh the risks
• It is not known if phenazopyridine is present in breast milk; because many drugs are present in breast milk, avoid use in nursing mothers

• Take phenazopyridine exactly as prescribed or as per label instructions
• Phenazopyridine may stain contact lenses or clothing; handle with care
• Store phenazopyridine safely out of reach of children
• Phenazopyridine does not treat urinary infection, it is only an analgesic; do not use to treat infection
• If you use over-the-counter phenazopyridine, do not use for longer than 2 days; seek medical help if symptoms continue or if you experience adverse effects
• Check with your doctor before using phenazopyridine if you have kidney disease