Joe Grinsteiner is a gregarious on-line character who touts the anti-parasitic drug ivermectin. In a current Fb video, he produced a tube of veterinary-grade ivermectin paste — the type made for deworming horses.

He gave the tube a squeeze. Then he licked a slug of the stuff, and gulped.

“Yum,” Mr. Grinsteiner stated within the Feb. 25 video, certainly one of quite a lot of ivermectin-related posts he has made which have drawn tens of millions of views on Fb this yr. “Really, that tastes like useless most cancers.”

Ivermectin, a drug confirmed to deal with sure parasitic illnesses, exploded in reputation in the course of the pandemic amid false claims that it might deal with or stop Covid-19. Now — regardless of a persistent message from federal well being officers that its medical advantages are restricted — curiosity in ivermectin is rising once more, notably amongst American conservatives who’re seeing it promoted by right-wing influencers.

Mr. Grinsteiner, 54, is a Trump supporter and nation music performer who lives in rural Michigan. He has claimed in his movies that ivermectin cured his pores and skin most cancers, in addition to his spouse’s cervical most cancers. In a video final month, he stated a girl instructed him her nonverbal autistic baby had change into verbal after utilizing ivermectin. In a current cellphone interview, Mr. Grinsteiner stated that he takes a each day dose of ivermectin to take care of his common well-being.

There isn’t a proof to help folks taking ivermectin to deal with most cancers or autism. But Mr. Grinsteiner believes that the medical and political institutions simply need to maintain common folks from discovering the therapeutic powers of a comparatively reasonably priced drug.

“These guys are completely cash pushed,” he stated in a single video. “And once I say ‘these guys,’ I’m speaking about all these politicians in Washington taking cash from the large pharma.”

Certainly, ivermectin has change into a kind of enduring pharmacological MAGA hat: an emblem of resistance to what some within the motion describe as an elitist and corrupt cabal of politicians, scientists and medical consultants. Whereas a lot of these consultants concern that misinformation about ivermectin might result in overdoses — or immediate folks to reject confirmed remedies for Covid or different illnesses — conservative lawmakers in quite a lot of states are selling laws that might enable ivermectin to be offered and not using a prescription, typically within the title of medical freedom.

Final week, Gov. Sarah Huckabee Sanders of Arkansas signed a regulation permitting ivermectin to be offered over-the-counter. Different laws is pending in at the least six different states: Kentucky, West Virginia, Louisiana, Georgia, Alabama and Texas. In 2022, Tennessee handed a regulation making it simpler to get ivermectin from a pharmacist.

President Trump’s new well being secretary, Robert F. Kennedy Jr., has up to now embraced the concept that ivermectin can deal with Covid, however whether or not he may search to combine the drug into his “Make America Wholesome Once more” agenda stays unclear. Mr. Kennedy didn’t reply to a request for an interview for this text.

However in 2021, he filed a petition with the Meals and Drug Administration asking officers to de-authorize the Covid vaccine, arguing that ivermectin was safer.

The Meals and Drug Administration continues to emphasise that it has not approved or authorised ivermectin for treating Covid, noting on its web site that “at present out there medical trial information don’t reveal that ivermectin is efficient in opposition to Covid-19 in people.” Dr. Robert Califf, who led the F.D.A. in the course of the Obama and Biden administrations, stated he was involved about folks selecting ivermectin over confirmed remedies, like vaccination for Covid or chemotherapy for most cancers. He stated he was additionally involved about overdoses, notably in folks taking the veterinary type of the drug. In excessive doses, ivermectin may be poisonous and trigger central nervous system issues like blurred imaginative and prescient, confusion and seizures. The F.D.A. has additionally warned that excessive doses can result in coma or dying.

Proper-wing media, nonetheless, is filled with commercials for the drug; some advertisements describe it as an integral part of survivalist instrument kits. The web site Gateway Pundit not too long ago ran a sponsored submit from a web based firm that gives prescription ivermectin for “stockpiling” functions, with an illustration of a postapocalyptic avenue scene.

Two main figures within the MAGA motion — former Consultant Matt Gaetz of Florida and Dan Bongino, the deputy director of the F.B.I., have promoted All Household Pharmacy, a web based outfit that dispenses ivermectin with “a prescription from our licensed medical doctors.”

“No extra preventing the system for the remedies you need,” Mr. Bongino stated on an episode of his widespread podcast, certainly one of his final earlier than beginning on the F.B.I. “Top off now earlier than the following disaster hits.”

The continued curiosity in ivermectin comes as little shock to Lewis A. Grossman, a regulation professor and historian at American College who has written extensively concerning the idea of “therapeutic alternative.” Mr. Grossman stated that over the course of American historical past, quite a lot of remedies have change into widespread regardless of having little or no buy-in from medical consultants.

For instance, he stated, laetrile, an unproven most cancers treatment derived from apricot pits, surged in reputation within the Nineteen Seventies; the actor Steve McQueen used it in his unsuccessful combat in opposition to most cancers.

On the peak of laetrile’s reputation, proponents praised its affordability and railed in opposition to a giant medicine-government “conspiracy” in opposition to it, whereas many consultants categorized it as quackery. The F.D.A. by no means authorised it for treating most cancers or some other therapeutic use, stated Mr. Grossman, who’s writing a e-book about laetrile referred to as “Seeds of Revolt.”

“The ivermectin story matches inside a really, very lengthy custom in America of individuals latching on to nonorthodox therapies based mostly partially on their suspicion that, for profit-maximizing causes, drug corporations and physicians are suppressing reality about them,” Mr. Grossman stated.

Mr. Grinsteiner stated that he was acquainted with ivermectin as a result of he runs a small farm and makes use of it on a few of his livestock. Suspicious of the Covid vaccine, he determined to take ivermectin preventively in the course of the pandemic as an alternative. His spouse did in order properly.

She bought pregnant six months after she began taking ivermectin commonly. They went to the physician, Mr. Grinsteiner stated, and came upon that her beforehand recognized cervical most cancers had cleared up. He additionally stated that he rubbed ivermectin on a cancerous spot on his nostril. He added that the spot cleared up and that a health care provider later instructed him the most cancers was gone.

He made his first Fb video about his expertise with ivermectin in January. “It was like, possibly a minute video, and I went to mattress,” he stated. “And I awakened and my cellphone was simply melting.”

Fb briefly suspended his account, then reinstated it. The corporate has appended to a few of his movies hyperlinks to a “context” web page from the fact-checking group Science Suggestions.

The web page notes that ivermectin and one other anti-parasitic drug, mebendazole, have proven “promising anticancer results in in vitro and animal research. Nonetheless, preclinical research can’t reliably predict a drug’s effectiveness in opposition to most cancers in people, and drug candidates that present effectiveness in cells and animals typically fail in medical trials.”

Nonetheless, Mr. Grinsteiner has been annoyed with Fb and has began a stand-alone web site that he typically mentions in his Fb posts. On the positioning, Mr. Grinsteiner says he doesn’t give recommendation on “what to take and (or) take it.” Fairly, he stated, it’s a place for folks to match notes.

So far, guests to the positioning have mentioned ivermectin as a possible therapy for neuropathy, renal failure, lupus and different maladies. Mr. Grinsteiner sells a T-shirt for $15.68 that declares, “I want ivermectin labored on the parasites in D.C.!”

Various the lawmakers pushing to make ivermectin simpler to purchase of their states say they need to assist constituents who’re already taking it, a few of whom use veterinary-grade ivermectin as a result of they can not get it at a daily drugstore.

“Constituents introduced it to me; it wasn’t one thing I assumed up by myself,” stated State Senator Alan Clark of Arkansas, the Republican who sponsored the brand new regulation there.

“Principally they’re going to the ag retailer” for ivermectin, Mr. Clark stated. “And it might be a lot safer for them to make use of what is meant for human consumption.”

Professor Grossman stated that it has lengthy been assumed that states don’t have the authority below federal regulation to make a prescription drug out there over-the-counter.

Many lawmakers looking for to ease entry to ivermectin, like State Consultant Wes Virdell of Texas, say they’re selling what Mr. Virdell, a Republican, calls “medical freedom.”

“I feel folks ought to have the ability to select no matter route they need” to deal with themselves, he stated. “Even when they’re fallacious, proper?”

Dr. Califf, the previous F.D.A. commissioner, sees it otherwise.

“All interventions have dangers,” he stated. “And in case you have no profit, and you’ve got some threat, then why on earth — you realize, there’s no rational motive why somebody ought to take the intervention.”

Dani Blum contributed reporting.