Purchases of ivermectin to treat COVID-19 have increased rapidly since July, according to an Aug. 26 report from the Centers for Disease Control and Prevention.

Ivermectin is a deworming agent used in livestock and house pets like cats and dogs, said Dr. Katrina Mealey, regents professor at WSU’s College of Veterinary Medicine. It can be used to treat a wide range of parasites and is not approved by the U.S. Food and Drug Administration to treat COVID-19.

A few studies in petri dishes showed some activity to slow down viral replication, she said. Small studies in people have shown it might be effective in humans, but other studies do not.

“There’s just not enough data to say yet one way or the other,” Mealey said.

The compound developed into ivermectin was discovered in a soil sample in Japan, Mealey said. Fungal organisms in the soil produce the compound, which shows antiparasitic activity.

At the time of its discovery, livestock were developing resistance to other antiparasitic drugs, she said. Parasites can be devastating for livestock.

“It was a game-changer drug,” Mealey said.

Ivermectin can also be prescribed in topical form for humans to treat head lice and rosacea, according to the CDC report.

Ivermectin was considered safe for mammals because it can treat parasites without damaging the mammal’s brain, Mealey said. Many mammals have a protein in their brain that pumps the chemical out, thus protecting it.

Some animals have a genetic mutation that prevents the protection process. Mealey made this discovery when veterinarians started using the drug in dogs, and certain breeds either died or went into comas. A similar mutation that has the same effect also exists in humans, Mealey said.

There can be serious consequences if a human or animal has the protein mutation, and they consume ivermectin. One of her biggest concerns is that it can cause central nervous system depression, she said. This means that ivermectin can lower brain activity with life-threatening results.

“With a regular dose, you could go into a coma,” Mealey said.

Too high of a dosage can have the same effect as the genetic mutation. People have inadvertently put their dogs into comas by using the ivermectin product meant for horses and miscalculating how much they should give dogs. The same could happen for people, she said.

The College of Veterinary Medicine tests cats and dogs for the genetic mutation that indicates whether it is safe for them to use ivermectin. Several people have called and asked if the college would test human samples for the human mutation. The college does not perform diagnostics for humans, Mealey said.

Pullman’s Four Star Supply, Inc. has received similar phone calls. Several people called to inquire about ivermectin and asked if the store carried it, said manager Darwin Hendrickson.

Hendrickson said he was unsure whether people have bought ivermectin products with the intention of consuming them. A few people came into the store to look at the products in the last few weeks.

Ivermectin can also interact with other prescription drugs, which is another reason why people should not consume it unless it has been prescribed to them by their healthcare provider, Mealey said.

The Washington Poison Center received a few calls regarding ivermectin, said Medical Director Dr. Scott Phillips. Fewer than 10 people from Washington state called the WPC during August. Of those, none were experiencing life-threatening reactions to the drug, he said. 

Animal owners should have a prescription or written notice from their veterinarian to treat the animal with ivermectin, Mealey said. ​​