AN ANTI-PARASITIC DRUG that was falsely held up as a cure for Covid during the pandemic is now being pushed again, this time as a cure for cancer.

“Cancer cure suppressed= medical genocide!!” reads a post on Facebook, which has accumulated hundreds of likes since being posted in an Irish fringe group on the platform on 27 April.

The post also contains a screenshot of an episode from the Joe Rogan Podcast featuring the actor Mel Gibson. The caption says that “84.4% of cancer patients taking ivermectin and mebendazole for 6 months” had seen their cancer stop spreading, shrink, or disappear.

‘Horse dewormer’

Both ivermectin and mebendazole are antiparasitic drugs. Ivermectin is often described as horse dewormer, which is one of its common uses.

Both drugs are also used to treat humans infected with parasites.

Fenbendazole, another antiparasitic drug that is used in animals, regularly pops up in the same discussions about alternative cancer cures (often interchangably with ivermectin and mebendazole).

Ivermectin in particular became famous during the Covid pandemic, after preliminary reports suggested that extremely high doses could kill the disease-causing virus in lab settings.

At the time this happened, there were no vaccines or widely available treatments for Covid available, so ivermectin — a cheap, widely available medication — generated a lot of hype as a potential cure.

However, its results in treating humans infected with Covid were, at best, mixed.

Large-scale studies involving thousands of participants showed that patients treated with ivermectin were no better off at fighting off Covid than those who had been given a placebo.

Bad medicine

Despite the lack of proof that the antiparasitic ever worked at fighting Covid (which is caused by a virus, not a parasite), fringe medical groups latched on to any indications of ivermectin’s effectiveness and theorised that it was being suppressed by a vast conspiracy.

Numerous nefarious motives were suggested as to why this was happening.

They included false claims that efforts were being made to reduce the world’s population through Covid (which many believed to be a man-made virus), to encourage people to take vaccines (which did not yet exist), or to justify continued lockdowns.

In either case, for some, the reputation of ivermectin as a wonder drug wrongfully suppressed by the establishment had been established, despite evidence it had no effect on Covid.

Similarly, strong claims about the use of ivermectin and mebendazole to cure cancer have spread in such groups, often buoyed by 2025 comments made by actor Mel Gibson on The Joe Rogan Experience, which is consistently rated one of the most popular podcasts in the world.

Almost 100 minutes into the discussion, which meandered between various conspiracy theories and speculations about Covid and medicine, Gibson brought up the subject of cancer.

“I have three friends,” Gibson says. “All three of them had stage four cancer. All three of them don’t have cancer right now at all.”

Rogan asks what they had taken, before himself suggesting ivermectin and fenbendazole.

“Yeah, I’m hearing that a lot,” Rogan said. “There’s studies on that now.”

The pair then digress into talking about the therapeutic effects of drinking fabric dyes. “This stuff works, man,” Gibson concludes.

The pair agree that the potential cures they discussed are “demonised” because they are not profitable.

This is not true. Rather than being demonised or suppressed, ivermectin as a cure for cancer was and still is being actively researched.

The reason it is not commonly used as a cure for cancer is because tests haven’t shown the effects that Rogan and Gibson describe.

Positive findings

There are theoretical reasons to believe that antiparasitics could disrupt certain types of cancers. Furthermore, ivermectin is widely available, cheap and, while not totally safe, its risks have been widely studied.

However, the same could be said of many common medicines. What has the research into these drugs actually shown?

Going by the “Cancer cure suppressed= medical genocide!!” post in an Irish Facebook group, we would expect to see convincing published evidence of a medical effect.

The screenshot summary of research in the Facebook post is actually taken from the X account of Nicolas Hulscher, who describes himself as an epidemiologist, and whose posts touting antiparasitics as cures for cancer have been seen many millions of times.

“We are about to publish the LARGEST human ivermectin-cancer study ever conducted,” he wrote in one post that has been viewed more than 1,600,000 times since being posted on 24 March.

“After 6 months, many patients reported their cancer was GONE.”

That study was later published — but only online, not in any medical journal. It remains a “pre-print”, meaning that it has not passed any publication’s review process.

This is a problem for two major reasons. Firstly, not being published in a journal means that the research isn’t reviewed by anyone other than Hulscher and his co-authors, all but one of whom have no previous records of scientific contributions.

The second problem is that Hulscher’s own previous research and publications have been heavily criticised as inaccurate.

In particular, he appears to spread misinformation to make vaccines appear harmful, and almost all of his previous publications are in this vein.

Even taking the paper itself on face value, there are glaring issues.

The study looked at “197 cancer patients who were prescribed ivermectin and mebendazole off-label through a telemedicine platform”.

The paper says, “data were collected via voluntary, standardized digital surveys”.

In other words, the paper looks at survey answers by people who had used the internet to procure drugs touted in alternative medical groups.

To be fair, in a rather different tone than Hulscher’s X posts, the paper acknowledges the study’s limitations “given the observational design, reliance on self-reported outcomes, and potential for selection bias and uncontrolled confounding”.

Reliable research

So, discounting exaggerated claims on social media, what does the more reliable research say?

Not much. A review of the research published last year found that “clinical evidence in humans is limited, with no large-scale randomized controlled trials (RCTs) confirming therapeutic benefits”.

That same review noted that lab and animal studies did indicate that there may be an effect, but also that the “risks of self-medication driven by social media touting Ivermectin’s unproven cancer benefits [...] can lead to toxicity in oncology patients”.

However, further research is already underway, most notably under the National Cancer Institute (NCI), a US research agency that has shifted its focus under the Trump administration.

It is unclear why the NCI has focused on this drug; the Trump-appointed director had said that “there are enough reports of it, enough interest in it,” in February when announcing the planned research into antiparasitics.

More recently, US President Donald Trump said that his shift in policy to support clinical trials of psychedelics was directly due to Joe Rogan’s influence, indicating that the podcaster’s preferences have had significant effects on US health policy.

Although the effects of these policy changes are yet to be seen, health experts have already criticised the renewed focus on antiparasitics in the NCI for moving funds away from more promising treatments.

Claims that ivermectin can cure cancer are completely unproven. Nevertheless, they have been bolstered by famous figures and have shaped the cancer research priorities of the United States.

Rather than being suppressed, research into ivermectin was ongoing, and the American government has said it will now boost it even further.

The Journal’s FactCheck is a signatory to the International Fact-Checking Network’s Code of Principles. You can read it here. For information on how FactCheck works, what the verdicts mean, and how you can take part, check out our Reader’s Guide here. You can read about the team of editors and reporters who work on the factchecks here.