Does Fenbendazole Work in Humans?

A dog wormer ingredient has been widely touted as a cancer cure in videos posted to Facebook and TikTok. But experts say there is no evidence that fenbendazole (FZ) works in humans.

The broad-spectrum benzimidazole antibiotic fenbendazole is a potent inhibitor of gastrointestinal parasites in many vertebrates including mammals. It is commonly used in veterinary medicine to treat giardia, roundworms, hookworms, whipworms, and the tapeworm genus Taenia in dogs, cattle, rabbits, ferrets, guinea pigs, sheep, horses, chickens, and fish as well as to control schistosoma in shrimp tanks.

Several studies have shown that fenbendazole inhibits the growth of tumors in animals and human cells, but the exact mechanism remains unclear. Among the several mechanisms suggested, it suppresses the formation of microtubules that provide structure to the cell. The drug also blocks the activity of a protein that normally helps the cell produce apoptosis-inducing proteins, such as p53 and p21.

For the experiments presented in Figure 1, we treated cultures with a range of concentrations of fenbendazole for 2 or 24 h, and then assayed cell survival using a colony formation assay. The results, shown as yield-corrected surviving fractions, reveal that the drugs are not toxic to aerobic EMT6 cells at doses close to the limit of solubility, but that at the highest concentration tested the drug reduces cell survival in severe hypoxia.

Moreover, we show that fenbendazole inhibits radiation-induced tumorigenesis and increases survival in 5-FU sensitive colorectal cancer cells SNU-C5 and SNU-C5/5-FUR by upregulating p53 expression, triggering apoptosis, autophagy, and necroptosis via glutathione peroxidase 4 (GPX4) induction in both cell types. fenbendazole for humans