Urinary Analgesic (Azo Dye)
Pregnancy: B
Phenazopyridine
Brand names: Pyridium
Adult dose
Dose: 200 mg three times daily after meals
Route: oral
Frequency: three times daily
Max: 600 mg/day
Short-term use only (max 2 days); symptomatic relief while awaiting antibiotic effect; turns urine/tears orange-red — warn patient
Paediatric dose
Dose: 4 mg/kg
Route: oral
Frequency: three times daily
Max: 200 mg three times daily
Caution in children; G6PD deficiency contraindication
Dose adjustments
Renal
Avoid in renal impairment (methaemoglobinaemia risk)
Hepatic
Avoid in hepatic impairment
Paediatric weight-based calculator
Caution in children; G6PD deficiency contraindication
Clinical pearls
- Analgesic effect only — does NOT treat infection; always prescribe with antibiotic
- Warn patients about orange-red urine staining — may stain clothes and contact lenses permanently
- Not widely available in UK (OTC in US); urinary antiseptics more commonly used
Contraindications
- Renal impairment
- G6PD deficiency
- Hepatic impairment
Side effects
- Orange-red urine/tears (stains contact lenses)
- Nausea
- Headache
- Methaemoglobinaemia (overdose)
- Haemolytic anaemia (G6PD deficiency)
Interactions
- Masks true urine colour — MSU should be collected before starting
Monitoring
- Renal function
- Signs of methaemoglobinaemia
Reference: BNFc; BNF 86. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators