Is Pyridium (phenazopyridine) safe to use during pregnancy?

Pyridium (Phenazopyridine) Use During Pregnancy

Direct Recommendation

Phenazopyridine can be used during pregnancy when clearly needed for symptomatic relief of urinary tract discomfort, as it is classified as FDA Pregnancy Category B with no evidence of fetal harm in animal studies or increased malformation risk in human pregnancies. 1, 2

Evidence-Based Safety Profile

FDA Classification and Animal Data

• The FDA drug label designates phenazopyridine as Pregnancy Category B, indicating reproduction studies in rats at doses up to 50 mg/kg/day revealed no evidence of impaired fertility or harm to the fetus 1
• No adequate and well-controlled studies exist in pregnant women, so the drug should be used during pregnancy only if clearly needed 1

Human Pregnancy Experience

• Existing data from clinical practice indicate that exposure to phenazopyridine during pregnancy is not associated with increased risk of fetal malformations 2
• This places phenazopyridine among the safer urinary tract medications available during pregnancy, alongside penicillins, cephalosporins, and nitrofurantoin 2

Clinical Application Algorithm

When to Use

• Symptomatic relief of dysuria, urgency, and burning associated with urinary tract infections or lower urinary tract irritation during any trimester 1, 2
• As an adjunct to antibiotics for UTI treatment, not as monotherapy for infection 2

Dosing Considerations

• Standard adult dosing applies during pregnancy (typically 200 mg three times daily after meals) 1
• Limit duration to 2 days maximum when used with antibiotics, as prolonged use is unnecessary once antibiotics take effect 1

Monitoring Requirements

• Watch for yellowish tinge of skin or sclera, which indicates accumulation due to impaired renal excretion and necessitates immediate discontinuation 1
• Ensure adequate renal function before prescribing, as the drug requires renal excretion 1

Important Caveats and Patient Counseling

Expected Effects (Not Complications)

• Inform patients that phenazopyridine produces reddish-orange discoloration of urine and may permanently stain fabric and contact lenses 1
• This discoloration is expected and not harmful 1

Laboratory Interference

• Phenazopyridine interferes with urinalysis based on spectrometry or color reactions due to its azo dye properties 1
• Collect urine specimens for culture before starting therapy to avoid diagnostic confusion 1

Contraindications in Pregnancy

• Avoid in patients with pre-existing renal impairment, as acute renal failure has been reported even with therapeutic doses in compromised kidneys 3
• Do not use in patients with glucose-6-phosphate dehydrogenase deficiency due to hemolytic anemia risk 1

Breastfeeding Considerations

• No information is available on the appearance of phenazopyridine or its metabolites in human milk 1
• Given the lack of data and the drug's azo dye properties, exercise caution during lactation and consider the necessity of the drug versus the benefits of breastfeeding 1

Comparison to Alternative Medications

• Phenazopyridine has a more favorable safety profile than trimethoprim-sulfamethoxazole, which should be avoided in the first trimester due to antifolate effects and neural tube defect risk 2
• It is comparable in safety to other Category B urinary medications like nitrofurantoin (though nitrofurantoin should be avoided near term due to hemolysis risk) 2