However, phenazopyridine has not undergone full FDA approval; it was “grandfathered” in before modern safety rules nypost.com. Animal studies conducted by the NIH in 2021 revealed that dietary exposure caused tumors in both mice and rats—liver tumors in female mice and colorectal tumors in both sexes—leading to its classification as “reasonably anticipated to be a human carcinogen” nypost.com+2ncbi.nlm.nih.gov+2thesun.ie+2.
Beyond the cancer risk, medical professionals warn that phenazopyridine can mask UTI symptoms, potentially delaying necessary antibiotic treatment ncbi.nlm.nih.gov+13en.wikipedia.org+13nypost.com+13. Other possible adverse reactions range from dizziness, nausea, and chest tightness to rare but serious effects such as kidney failure, seizures, blood disorders like methemoglobinemia, and even death nypost.com. Its label even cautions users about carcinogenic warnings under California’s Proposition 65 en.wikipedia.org+10dentistryiq.com+10ncbi.nlm.nih.gov+10.
For those seeking symptom relief during a UTI, safer alternatives exist. Over-the-counter combinations containing methenamine and sodium salicylate (e.g., Cystex) operate as urinary antiseptics and carry a lower risk profile the-independent.com+12en.wikipedia.org+12thesun.ie+12. However, these too are not proven to cure infections—they only alleviate discomfort while awaiting antibiotic therapy, which remains the only cure nypost.com+3verywellhealth.com+3health.com+3. Patients should discuss options with their healthcare providers and use OTC aids only short‑term.
Disclaimer: This article is for informational purposes only and should not be taken as medical advice. Always consult a qualified healthcare professional before starting or stopping any medication.
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