From the FDA Drug Label
PRECAUTIONS General A yellowish tinge of the skin or sclera may indicate accumulation due to impaired renal excretion and the need to discontinue therapy. Carcinogenesis, Mutagenesis, Impairment of Fertility Long-term administration of Phenazopyridine HCl has induced neoplasia in rats (large intestine) and mice (liver) Although no association between Phenazopyridine HCl and human neoplasia has been reported, adequate epidemiological studies along these lines have not been conducted.
The main risks associated with prolonged pyridium use are:
- Accumulation due to impaired renal excretion, which may require discontinuation of therapy
- Neoplasia, as evidenced by long-term administration inducing tumors in rats and mice, although no association with human neoplasia has been reported 1
From the Research
Prolonged use of pyridium (phenazopyridine) should be limited to no more than 2 days due to several significant risks, as supported by the most recent and highest quality study available 2. The primary concerns include methemoglobinemia, which reduces oxygen-carrying capacity in the blood; hemolytic anemia, where red blood cells are destroyed faster than they can be made; nephrotoxicity that can damage kidney function; and hepatotoxicity that may impair liver function. Pyridium can also cause crystalluria, where crystals form in the urine potentially leading to kidney stones. Long-term use may mask symptoms of underlying urinary tract infections, delaying proper diagnosis and treatment. Some studies have reported adverse effects of pyridium, including a case report of multiple adverse effects, including myelosuppressive pancytopenia 3. However, a more recent study found no difference in adverse drug reactions among patients receiving phenazopyridine for >14 days compared to a matched comparator group 2. Another study found that phenazopyridine is an effective and well-tolerated drug for symptomatic therapy in patients with acute uncomplicated cystitis 4. Despite these findings, the risks associated with prolonged use of pyridium outweigh the benefits, and patients should be aware of the potential risks and limitations of this medication. Patients should be aware that pyridium turns urine orange-red, which is normal but can stain clothing and contact lenses. This medication is intended only for short-term symptom relief of urinary pain, burning, and discomfort while the underlying condition is being treated with appropriate antibiotics or other therapies. If urinary symptoms persist beyond 2 days, patients should discontinue pyridium and consult their healthcare provider for further evaluation rather than continuing the medication. Key points to consider when prescribing pyridium include:
- Limiting use to no more than 2 days
- Monitoring for signs of methemoglobinemia, hemolytic anemia, nephrotoxicity, and hepatotoxicity
- Informing patients of the potential risks and limitations of the medication
- Advising patients to discontinue use and consult their healthcare provider if symptoms persist beyond 2 days.