The benzimidazole medication fenbendazole, widely used in veterinary medicine to treat animal gastrointestinal parasites, has been shown to slow cancer growth in cells and in animals. But this early research suggests that fenbendazole may only be helpful as part of a complete treatment regimen, along with other drugs and radiation therapy.

Although fenbendazole is FDA-approved for use in humans to treat parasites, there is little evidence that it has any anticancer effects in people. And a recent series of videos posted on social media site TikTok featuring a Canadian veterinarian who claims that using fenbendazole and other treatments cured him of small-cell lung cancer has sparked much concern about the drug’s potential for harming patients.

The videos were taken by Andrew Jones, a veterinarian who was reprimanded in 2019 for promoting alternative medicines for his pet patients and was recently banned from practicing in the province of British Columbia. The TikTok clips are based on the story of Brian Tippens, a former member of the College of Veterinarians of British Columbia, who claims that taking fenbendazole and other traditional therapies cured him of his small-cell lung cancer. But a recent study showed that fenbendazole does not stop cancer growth in mice with the EMT6 tumor, and it has no effect on the growth of irradiated tumors. The study used a rigorous colony formation assay to measure cell viability and found that fenbendazole had both cytotoxic and cytostatic effects in the cell culture experiments. Severe hypoxia greatly increased the toxicity of 2-h treatments with fenbendazole, but even these high concentrations did not significantly decrease cell numbers in cultures as measured by surviving fractions. fenbendazole for cancer