That Common UTI Relief? It Might Come with Cancer Risks.
Phenazopyridine has long been used for UTI relief—but new studies raise concerns about its safety as research links it to potential cancer risks.
If you’ve ever experienced the burning discomfort of a UTI (the absolute worst), you’ve probably grabbed an over-the-counter remedy like AZO or Uristat. These medications contain phenazopyridine, a drug that numbs your urinary tract to ease that miserable burning sensation (while turning your urine neon orange).
But recently, there's been concern about whether phenazopyridine might pose long-term health risks, particularly cancer.
The Cancer Connection: What The Research Shows
The concern stems back to animal studies by the National Toxicology Program (NTP), which found that when rodents were fed phenazopyridine hydrochloride, they developed tumors.
- Zoom In: In female mice, the phenazopyridine triggered both benign and malignant liver tumors. In male and female rats, it caused benign or malignant colorectal tumors.
Based on these results, the NTP now classifies phenazopyridine hydrochloride as "reasonably anticipated to be a human carcinogen.”
However! There’s currently no direct evidence linking phenazopyridine to cancer in humans. And while animal studies are a useful starting point, we don’t share a rodent’s metabolism, lifespan, or biology (thankfully).
How Did Phenazopyridine Get on The Market?
If phenazopyridine raises cancer concerns in lab mice, how did this stuff end up on the shelves of our local CVS? Turns out, it was first adopted by US pharmacies in 1928, long before the FDA had the rigorous approval process it uses today.
That means phenazopyridine was “grandfathered” into the market without the safety evaluations we’d expect from a new drug today. But has the FDA done anything about it since?
The FDA’s Stance on Phenazopyridine Today
The FDA has quietly acknowledged some potential risks. In 2003, the agency called for safety and efficacy data on all over-the-counter urinary pain relievers, including phenazopyridine. They also added a carcinogenicity warning to the label, which reads:
“Long-term administration of phenazopyridine hydrochloride has induced neoplasia in rats (large intestine) and mice (liver).”
Here’s the issue: “Long-term” isn’t clearly defined. And despite the warning, doctors, including OBGYNs, still routinely recommend these products for symptomatic relief of UTIs. As recently as two years ago, I was still recommending this for my patients with UTIs and have even taken it myself!
What To Do If You Take Phenazopyridine
If your UTI has you sprinting to the pharmacy for over-the-counter relief, here's what to remember:
- Use phenazopyridine for a maximum of two days. Any longer, and it might hide symptoms of a more serious infection, delaying proper treatment.
- Mention it to your doctor, especially if you have underlying health conditions or are taking other medications.
- Be aware of potential side effects. They include dizziness, headaches, and, in rare cases, methemoglobinemia—a condition that affects the blood's ability to carry oxygen.
Are There Phenazopyridine Alternatives?
Given the hubbub around phenazopyridine, here are some tried-and-true alternatives (and a few ways to prevent UTIs in the first place):
- Antibiotics: This should be your go-to for treating UTIs. Be sure to finish the full course to ensure the infection is fully eradicated. (Note: Data has shown that about 40% of UTIs resolve without antibiotics. But those few days might be very uncomfortable!)
- Hydration: Drinking plenty of water can help flush bacteria from the urinary tract.
- Hygiene Practices: This includes wiping from front to back and urinating after sexual activity. Not glamorous, but it works.
- Regular Medical Check-Ups: Regular visits to your doctor can catch issues early and keep your urinary tract healthy.
