A cancer charity has seen a rise in patients seeking information about an anti-parasitic drug after a Hollywood actor suggested it could cure the disease. Macmillan Cancer Support found dozens of mentions of ivermectin in its online community forums over the last year. The drug, discovered in the 1970s, was initially used in veterinary medicine and later licensed for treating parasitic infections in humans.
Earlier this year, Mel Gibson claimed on a US podcast that three of his friends had been cured of stage four cancer after taking it and another anti-parasitic drug, fenbendazole. His comments are thought to have fuelled a rise in online discussions about he drug as a possible cancer therapy. However, Macmillan’s chief medical officer Professor Richard Simcock said there was “zero real-world clinical evidence that it might be helpful in the treatment of cancer”.
He added: “Over the last decade there have been multiple studies which show that ivermectin and drugs like it have some effect on cancer cells in the laboratory. This is not very surprising.
“In fact, there are thousands of substances which can be toxic to cancer cells grown in the glass (in vitro) of a laboratory test tube. However, taking that evidence and showing that it can be effective in ‘life’ (in vivo) is a far more challenging ask.”
There has only been one small clinical trial which looked at using ivermectin for breast cancer, Prof Simcock said. Of eight patients included, only one saw cancer shrinkage — and this occurred when the drug was used alongside another proven therapy.
He added: “Even the scientists who have been most interested in this research have suggested that any potential positive effect is only likely to be seen if the drug is combined with conventional therapies, rather than as substitute for standard treatments.”
The charity said reports had emerged online of patients obtaining ivermectin from various sources including veterinary paste.
Prof Simcock said Mel’s claims appeared to have “lit a rocket underneath interest in ivermectin”.
He added: ”For people with cancer, researching every option that is available to them can be a form of autonomy. It is a method of regaining some control over a situation in which people often feel powerless. I suspect I would do the same.
“If that search suggests ivermectin as a possible treatment, then as healthcare professionals we need to understand the current evidence and be able to have the trust of people with cancer to explain why this evidence would tell us that taking the drug is not sensible or helpful.
“For example, side effects of ivermectin include skin reactions, followed by abdominal pain, fatigue, loss of appetite and 37 other possible problems listed in the British National Formulary.”
The drug was also controversially touted as a treatment for Covid during the pandemic. A large suit led by the University of Oxford found it did not improve recover times, reduce hospital admissions or cut mortality rates.
Claims about ivermectin and cancer are part of a wider trend of health myths spreading online, particularly via social media.
Prof Simcock added: “For anyone with cancer who has questions about ivermectin, I would urge them to speak to their healthcare team. Macmillan’s clinical experts on our Support Line are also available 8am – 8pm to support anyone living with or affected by cancer with any questions or concerns they may have.”
