From the FDA Drug Label
NOTE : Patients should be informed that Phenazopyridine HCl produces a reddish-orange discoloration of the urine and may stain fabric Due to its properties as an azo dye, Phenazopyridine HCl may interfere with urinalysis based on spectrometry or color reactions. Azo refers to a type of dye, and in the context of Phenazopyridine HCl, it is an azo dye that can cause a reddish-orange discoloration of the urine and may interfere with certain laboratory tests. 1
From the Research
Azo is a brand name for over-the-counter medications primarily used to treat urinary tract symptoms, with the main active ingredient being phenazopyridine hydrochloride, which acts as a urinary analgesic (pain reliever) that soothes the lining of the urinary tract, as shown in a recent study 2.
Key Points
- Azo Standard is commonly used to relieve symptoms of urinary tract infections (UTIs) such as pain, burning, urgency, and frequency while waiting for antibiotics to take effect.
- The typical adult dose is 2 tablets (95-97.5 mg each) three times daily with or after meals.
- It's essential to note that Azo only treats symptoms and does not cure infections, so medical treatment should still be sought for suspected UTIs.
- The medication works by directly acting on the urinary tract tissues to provide local anesthetic effects.
- Users should be aware that Azo causes urine to turn orange or reddish, which is normal and harmless.
- Treatment should generally not exceed 2 days without medical supervision, and those with kidney disease should consult a healthcare provider before use, as phenazopyridine can cause acute interstitial nephritis, as reported in a case study 3.
Safety and Efficacy
- A recent study found that phenazopyridine is an effective and well-tolerated drug for symptomatic therapy in patients with acute uncomplicated cystitis, with significant improvement in symptoms after 6 hours of treatment 2.
- Another study found that long-term use of phenazopyridine for radiation cystitis did not increase the incidence of adverse drug reactions compared to a matched comparator group 4.
- However, it's crucial to consider the potential risks and benefits of using phenazopyridine, especially in patients with kidney disease or those taking other medications, as highlighted in a review of urinary tract analgesics 5.