No proof that the dog deworming drug fenbendazole can cure human cancer

A video shared on Facebook tells about an Oklahoma man who said his cancer was cured by a dog deworming medicine.

The video includes clips from a 2019 news story aired by KOCO-TV in Oklahoma City. In the clips, Joe Tippens said he had small-cell lung cancer that spread to his organs and bones, and that he was told he had a short time to live. Tippens said he was cured by fenbendazole, a dog dewormer, which a veterinarian had recommended to him.

Text posted with the video says: "Dewormer for who? Dewormer cured what?"

The post was flagged as part of Facebook’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Meta, which owns Facebook and Instagram.)

Some peer-reviewed studies have found potential in fenbendazole treating human cancer and recommended further study. But there is no proof it’s a cure. The National Cancer Institute said it has no evidence supporting the claim. And the Food and Drug Administration has not authorized fenbendazole for treating or preventing cancer in humans.

The news story said that although Tippens credited fenbendazole with ridding him of cancer, he also took an experimental cancer-fighting drug and supplements. 

The late Dr. Stephen Prescott, a cancer researcher and then-president of the Oklahoma Medical Research Foundation, was also interviewed about Tippens. He said he was skeptical, but that more study of fenbendazole was worthwhile. 

Prescott died of cancer in 2021. 

Some peer-reviewed studies have signaled potential for fenbendazole as a cancer treatment. 

In 2013, using mouse cells, Yale University researchers found "no evidence that fenbendazole would have value in cancer therapy," but that this general class of compounds merited more study.

In 2022, two studies judged fenbendazole to be a possible human cancer treatment. Chinese researchers found that fenbendazole "can effectively restrict the growth" of human cervical cancer cells, without "severe toxic side effects." South Korean researchers examining human cells reported that fenbendazole "may be a potential alternative treatment" for human colorectal cancer and recommended further study.

Although it didn’t comment on those two studies, the University of Wisconsin-Madison Carbone Cancer Center told PolitiFact that research on fenbendazole has produced "intriguing preliminary data" that merits further study, but that the drug is not a curative treatment.

People should not take fenbendazole for cancer treatment unless it is part of a clinical trial, and people who do take it "should disclose that to their health care team immediately," the center said. Clinical trials precede regulatory drug approvals.

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But researchers have also urged caution. 

In October, South Korean cancer researchers wrote that a   "fenbendazole scandal" originated with Tippens’ claim and was amplified when fenbendazole was touted by a South Korean celebrity, who later disavowed the drug. Tippens’ cure likely was because of his participation in the clinical trial for the cancer drug Keytruda, but South Korean cancer patients ignored warnings about fenbendazole and took it widely, the article said. 

Also in October, in an article titled, "Fenbendazole Fever," South Korean researchers reviewed studies on the drug and human cancer. 

"Despite the potential anticancer capabilities of fenbendazole, its pharmacokinetics, safety and tolerance profiles in humans must be confirmed in extensive clinical trials before it can be used in any therapeutic context," they concluded. "Experts must further attempt to provide patients with reliable medical information."

Responding to the Facebook claim, two federal agencies told PolitiFact that fenbendazole is not approved for human cancer treatment.

The National Cancer Institute said it "disseminates evidence-based, scientifically accurate information about cancer to the public. It does not appear from a search of our resources that the NCI maintains any information supporting this claim."

The Food and Drug Administration said fenbendazole is an active ingredient in multiple FDA-approved drugs "that are intended for the treatment and control of internal parasites in certain animals."

The FDA said it has not authorized or approved fenbendazole for treating or preventing cancer in humans. "Never use medications intended for animals on yourself or other people," the agency said. "Animal products are very different from those approved for humans and may cause toxicity and interfere with other medications."

A post shared on Facebook claimed that the dog dewormer drug fenbendazole can cure cancer in humans.

Some peer-reviewed studies suggest fenbendazole has potential as a human cancer treatment. But researchers said more study is needed and the federal cancer agency said it has no research that supports the claim.

Fenbendazole is not approved by the FDA for treating cancer.

We rate this claim False.

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