Possible cancer risk linked to common OTC drug

Phenazopyridine is an over-the-counter (OTC) drug primarily used to treat urinary tract infections (UTIs). Known under the brand names Azi or Uristat, it is widely available in the US and can be purchased in local pharmacies or stores like Target and Walmart. The only problem is that phenazopyridine is not FDA-approved—and it may cause cancer.¹

Blurred safety lines

This drug has not been FDA-approved because it, along with other OTC medications, has been around longer than the FDA's formal rules for approval. Since it does not require a prescription, anybody with a UTI can walk into a pharmacy, purchase, and consume phenazopyridine without knowing if it's safe.¹

Although generally effective, this drug can slow breathing or even cause death in high enough doses or though extended use. Having access to a product like this is particularly dangerous since, according to Bloomberg News, some doctors have recommended phenazopyridine without fully understanding its risks.

Phenazopyridine's link to cancer

A 1978 study found that tumors developed in the lab rats and mice exposed to this product. More recently, a report from the National Toxicology Program noted that: "Phenazopyridine hydrochloride is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals."²

There is no explicit warning label on the outside of the box warning consumers of this.

Aaron Kesselheim, a professor of medicine at Harvard Medical School, said: "If they're [phenazopyridine and others] are available at the pharmacy, people assume they're overseen by the FDA, but unfortunately, in the case of these unapproved drugs, they aren't."¹

Women at risk and the role of the dental professional

As it is used to treat UTIs, phenazopyridine may be purchased and consumed by over 100 million women; the Urology Care Foundation reported that 60% of US women get at least one UTI in their lifetime.1 Furthermore, many urinary tract infections are caused by biofilm infections, which can be difficult to cure due to high levels of antimicrobial resistance.³

Patti DiGangi, RDH, noted that: "Just as with the UTI, testing for pathogenic bacteria and genetic risk is appropriate prior to treating a patient's periodontal disease." Performing salivary tests can help dental professionals not only diagnose periodontal infections, but design customized treatments plan for their patients.³

With millions potentially exposed, the risks of phenazopyridine highlight a critical gap in consumer awareness and regulatory oversight. Dental professionals, as frontline health providers, have a unique opportunity to educate patients about microbial risks and guide them toward safer, more informed choices-both orally and systemically.