What causes Phenazopyridine (Pyridium) to turn urine orange?

From the Guidelines

Pyridium (phenazopyridine) is expected to cause a temporary orange to reddish-orange discoloration of urine, which is a harmless side effect that resolves once the medication is stopped. This color change is due to the medication being a dye that directly affects urine color as it's eliminated through the kidneys. Pyridium is a urinary tract analgesic that helps relieve pain, burning, urgency, and discomfort caused by urinary tract infections or procedures, as mentioned in the management of urinary toxicity in gynecological malignancies 1. The standard dosage is typically 200 mg three times daily, and it's usually prescribed for a short duration, such as two days, when used alongside antibiotics for UTIs.

• Key points to consider when taking Pyridium include:
  • The medication can stain clothing or contact lenses, so precautions should be taken while using it
  • Pyridium only treats urinary symptoms and doesn't cure infections, so completing the prescribed antibiotic course is crucial if taken for a UTI
  • If the orange urine persists more than 24 hours after stopping Pyridium, consulting a healthcare provider is recommended
• In the context of managing urinary toxicity, guidelines suggest that low-grade urinary symptoms can be managed with non-steroidal anti-inflammatory drugs, anticholinergic agents, or analgesics such as phenazopyridine, as stated in the position paper on behalf of the Italian Association of Radiotherapy and Clinical Oncology 1.
• It's essential to note that Pyridium is used to relieve symptoms, but it's not a cure for underlying conditions, and its use should be guided by a healthcare provider, especially in cases of refractory disease or when surgery is being considered.

From the FDA Drug Label

Patients should be informed that Phenazopyridine HCl produces a reddish-orange discoloration of the urine and may stain fabric

• Phenazopyridine (Pyridium) causes urine to turn reddish-orange due to its properties as an azo dye 2.
• This discoloration may also stain fabric and has been reported to stain contact lenses.

From the Research

Pyridium and Orange Urine

• Pyridium, also known as phenazopyridine, is a urinary tract analgesic that can cause urine to turn orange or red due to its azo dye structure 3.
• The drug is metabolized in the body and excreted in the urine, resulting in the characteristic color change 3.
• Studies have shown that phenazopyridine is effective in relieving symptoms of urinary tract infections, such as pain and discomfort, but it does not affect the underlying infection 4, 5.
• The color change caused by phenazopyridine is generally harmless and temporary, but it can stain clothing and other materials 3.

Mechanism of Action

• Phenazopyridine works by numbing the lining of the urinary tract, reducing pain and discomfort associated with urinary tract infections 4.
• The drug does not have antibacterial properties and should not be used as a substitute for antibiotic therapy 4, 5.
• Phenazopyridine can be used in combination with antibiotics to provide relief from symptoms while the infection is being treated 4.

Safety and Efficacy

• Studies have shown that phenazopyridine is generally safe and well-tolerated, with few adverse events reported 4, 5, 6.
• The drug can cause gastrointestinal side effects, such as nausea and vomiting, but these are typically mild and temporary 6.
• Phenazopyridine has been shown to be effective in relieving symptoms of urinary tract infections, including pain, discomfort, and frequency of urination 4, 5.