A plant extract trumpeted as a “cure” for COVID-19 by the leader of a pillow company is untested and potentially dangerous, scientists say.

Mike Lindell, the chief executive of MyPillow and a big donor to President Donald Trump, told Axios that the president was enthusiastic about the drug, called oleandrin, when he heard about it at a White House meeting.

“This thing works — it’s the miracle of all time,” said Lindell, who has a financial stake in the company that makes the compound.

However, no studies have shown that oleandrin is safe or effective as a coronavirus treatment. It’s unclear what dose the purported treatment would have, but ingesting even a tiny bit of the toxic shrub the compound comes from could kill you, experts said.

“Don’t mess with this plant,” said Cassandra Leah Quave, a medical ethnobotanist at Emory University.

Oleandrin is derived from Nerium oleander, a popular flowering Mediterranean shrub responsible for many cases of accidental poisoning. Oleandrin is the chemical that makes the plant deadly, Quave wrote in an article in the Conversation.

Ingesting any part of the plant — or even eating a snail that previously munched on its leaves — can cause an irregular heart beat and kill humans and animals, she and other doctors and scientists said.

So why would anyone think oleandrin could be a treatment for COVID?

It’s not uncommon for plants — even poisonous ones — to generate interest as treatments for disease. Robert Harrod, a professor at Southern Methodist University, has studied oleandrin’s potential to fight a type of leukemia, for example.

The U.S. Army Medical Research Institute of Infectious Diseases conducted a lab test in May to determine whether oleandrin could stop coronavirus infection in cells. The results were “inconclusive,” and the agency opted to discontinue this line of research, spokeswoman Lori Salvatore said.

Another cell study, which has not yet been published by a scientific journal, involved two employees of Phoenix Biotechnology, a San-Antonio based company that Lindell has a stake in. According to its website, the company has spent the last 20 years exploring the health benefits of oleandrin.

The study found that oleandrin could block the coronavirus in monkey cells in a test tube. But these so-called in vitro experiments do not tell us much, said scientists, one of whom conducted the study.

“The testing of antivirals on cells is only the first step,” said Scott Weaver, a virologist at University of Texas Medical Branch at Galveston, and one of study’s authors. “There are many drugs like this one that look promising during initial in vitro testing, but then fail later.”

Could Phoenix Biotechnology sell oleandrin as an over-the-counter supplement? Possibly.

Andrew Whitney, vice chairman and director, said he hopes Phoenix Biotechnology will be able to test the drug among people infected with coronavirus in hospitals. But he’s also looking into selling the extract as an over-the-counter dietary supplement. Vitamins, weight-loss pills, melatonin and other dietary supplements are not required to go through the FDA drug testing review process to be sold.