TORONTO -- The U.S. Food and Drug Association (FDA) has issued a plea for Americans to stop taking a drug often used as a de-wormer in livestock as a method to treat or prevent COVID-19.

In a tweet Saturday, the government agency said “You are not a horse. You are not a cow. Seriously, y’all. Stop it.”

That quip was followed by a link to a frequently asked questions page and an explainer on the dangers of humans ingesting ivermectin meant for animals.

“Ivermectin is often used in the U.S. to treat or prevent parasites in animals,” the U.S. FDA page states. “The FDA has received multiple reports of patients who have required medical support and been hospitalized after self-medicating with ivermectin intended for horses.”

On Friday, the Mississippi State Department of Health issued a stark warning on its Facebook page, warning residents: “Do not use ivermectin products made for animals.”

The Mississippi Poison Control Center also sent out an urgent bulletin Friday, saying they had “received an increasing number of calls from individuals with potential ivermectin exposure taken to treat or prevent COVID-19 infection.”

The centre said that at least 70 per cent of its recent calls have been related to ingestion of livestock or animal formulations of ivermectin purchased at livestock supply centres.

At least one person was hospitalized in relation to ivermectin meant for livestock, according to local reports.

Mississippi has the highest rate of COVID-19 cases in the U.S. according to the U.S. Centers for Disease Control, and is tied with Alabama for the lowest vaccination rate.

Despite the lack of any scientific evidence that ivermectin is an effective treatment for COVID-19, some of the drug's advocates have cited it as an alternative to approved COVID-19 vaccines and public health measures like physical distancing and wearing a mask.

Similar to then-U.S. president Donald Trump’s false claims about hydroxychloroquine being an alternative treatment for COVID-19, Brazilian President Jair Bolsonaro has publicly endorsed the drug.

A non-peer-reviewed pre-print study from 2020 that touted the drug is thought to have caused black market sales to surge and has even swayed government responses, especially in South America, throughout the pandemic. The paper was later retracted.

WHAT IS IVERMECTIN FOR?

In animals, ivermectin is used to prevent heartworm disease and certain internal and external parasites. The formula and dosage used for treating animals is vastly different than the ivermectin approved for use in humans.

The FDA has approved ivermectin in doses meant for humans to treat people with conditions caused by parasites and in some cases, as a topical agent for surface parasites like head lice.

“Ivermectin is not an anti-viral drug,” the agency states on its website. “There’s a lot of misinformation around, and you may have heard that it’s okay to take large doses of ivermectin. That is wrong.”

The FDA said that it is possible to overdose on ivermectin, which can cause nausea, vomiting, diarrhea, hypotension (low blood pressure), allergic reactions, dizziness, seizures, coma and death.

The FDA said it has not reviewed any data to support the use of ivermectin in COVID-19 patients, but did say “some research is underway” but did not elaborate.