LONDON: A widely used over-the-counter drug for urinary tract infection (UTI) relief, phenazopyridine hydrochloride, has been linked to potential cancer risks, raising concerns among healthcare professionals and regulatory authorities.
Phenazopyridine hydrochloride, the active ingredient in popular brands such as AZO, Pyridium, and Safrel, has long been used to ease symptoms such as pain, burning, and irritation caused by UTIs.
Despite its widespread use and reputation for providing rapid relief—often within 20 minutes—the drug has never been formally approved by the United States Food and Drug Administration (FDA).
Recent reports, including one published by Bloomberg, highlight growing apprehension over the drug’s safety profile.
Rita Jew, president of the Institute for Safe Medication Practices, told Bloomberg, “There is no need for this drug,” referring to the limited clinical evidence supporting its long-term use and the emerging cancer-related concerns.
Animal studies have played a key role in raising red flags. A 2021 study published by the National Institutes of Health (NIH) found that dietary exposure to phenazopyridine resulted in both benign and malignant liver tumours in female mice, and bowel tumours in male and female rodents.
Based on these findings, the NIH concluded the drug is “reasonably anticipated to be a human carcinogen.”
Consumer product labels have also acknowledged these risks. The packaging of AZO products notes that phenazopyridine hydrochloride is “known to the State of California to cause cancer.”
Similarly, URISTAT Pain Relief Tablet packaging states that long-term use of the drug has induced neoplasia—abnormal cell growth—in laboratory animals, although it emphasises that no definitive link to human cancer has been established due to the absence of comprehensive epidemiological studies.
Phenazopyridine has been on the radar for years. The New Jersey Department of Health listed it as a hazardous substance in 2001.
Despite this, the drug remains widely available without a prescription in the United States, where UTIs account for over eight million visits to healthcare providers each year, according to the American Urological Association.
Around 60 percent of women and 12 percent of men will experience at least one UTI in their lifetimes.
The drug is less accessible in countries like Australia, where it generally requires a prescription.
There, health authorities have taken a more cautious approach, citing the drug’s potential to mask serious infections and its possible side effects, which include upset stomach, discoloured urine, and in rare cases, methaemoglobinaemia—a potentially life-threatening blood disorder.
Despite the growing concerns, awareness among medical professionals appears limited. “It’s the first time I’m even hearing about this. I’m totally unaware,” New York-based gynaecologist Dr Steven Goldstein told Bloomberg.
