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The U.S. Food and Drug Administration is warning people not to take cow and horse deworming medication to treat COVID-19. 

Nevertheless, the medicine, Ivermectin, is flying off store shelves in Oklahoma.

Dr. Mary Clarke, with the Oklahoma State Medical Association, told KTLA sister station KFOR that Oklahomans are using the drug to treat or prevent the coronavirus, but its use could lead to long-term health problems. 

“Once the damage is done in these situations, you’re not going back,” Clark said. “The FDA has said, ‘Please, please, this is not something that is recommended,’ and the manufacturer of the actual medicine has said, ‘We have no evidence of effectiveness.'” 

Clarke said the drug, which has not been studied on humans, primarily treats or prevents parasites in animals. However, Clarke said there are two versions of Ivermectin.

“There’s a human-grade, but it’s for parasite infections,” said Clarke. “Twenty years ago was the last time that I’ve used Ivermectin on a human.”

The FDA said Ivermectin products for animals differ from those for people.

Ivermectin tablets are FDA-approved to treat people with two conditions caused by parasitic worms: intestinal strongyloidiasis and onchocerciasis. Also, some topical forms of the medication are approved to treat external parasites such as head lice and for skin conditions such as rosacea.

However, the FDA said, the drug is not approved to treat or prevent COVID-19 in people.

“Animal drugs are often highly concentrated because they are used for large animals like horses and cows, which can weigh a lot more than we do — a ton or more,” the FDA said. “Such high doses can be highly toxic in humans.”

KFOR contacted 12 Tractor Supply stores around Oklahoma, and they all said Ivermectin was sold out. 

“Ivermectin is gone within hours of shipment,” one store said.

 “I mean, we even have ‘Please don’t eat’ signs up,” another told KFOR.

 “We haven’t received a shipment in two weeks,” said a supply store. “I think it’s because people are consuming it.”    

With the pandemic still a real threat, the FDA said, it’s “perhaps not surprising that some consumers are looking at unconventional treatments.”

But, the agency said, unauthorized drugs are not recommended: “Using any treatment for COVID-19 that’s not approved or authorized by the FDA, unless part of a clinical trial, can cause serious harm.”

Doctors say don’t buy medicine from a feed store for human consumption. 

“There’s too much potential for error if a person goes and takes a veterinary product intended for large animals,” Scott Schaeffer with the Oklahoma Poison Control Center, said. 

Since May, there have been 10 poison calls related to Ivermectin. Diarrhea and vomiting are two of the many side effects you could experience. Some can be very serious.

“It could be dizziness, cardiac rhythm problems, blood pressure issues, primarily low blood pressure. Especially mix with some other medications,” Clarke said. “There is no dose. There’s no dose for this because there’s no evidence that this is going to work.”

Clarke said the best way to prevent COVID is to get vaccinated.

This week, the Associated Press reported that the Mississippi Health Department is warning people not to use livestock medicine to try to treat COVID-19. At least 70% of recent calls to the Mississippi Poison Control Center have been about people ingesting livestock or animal formulations of Ivermectin.

Mississippi continues to see a sharp increase in coronavirus cases.