Against the advice of medical experts, President Donald Trump again promoted the use of the anti-malarial drug hydroxychloroquine as treatment for coronavirus on Sunday, asking “What do you have to lose?” The American Medical Association’s top doctor says lives could be lost.

“There could be negative side effects,” said Dr. Patrice Harris, president of the AMA, during an interview with CNN’s Wolf Blitzer. “There could be deaths. This is a new virus, and so we should not be promoting any medication or drug for any disease that has not been proven and approved by the FDA.”

Harris was asked to weigh in on the president’s optimistic remarks from a press conference earlier Sunday, during which he again touted the drug, despite repeated warnings from the nation’s top infectious diseases expert, Dr. Anthony Fauci, that there is no strong evidence that it’s effective against coronavirus.

“What do you have to lose?” Trump asked during the White House briefing. “I want them to try it, and it may work and it may not work. But if it doesn’t work, there is nothing lost by doing it.”

According to the American Medical Association expert, there’s a lot to lose.

“You could lose your life,” Harris said. “It’s unproven. And so certainly there are some limited studies, as Dr. Fauci said. But at this point, we just don’t have the data to suggest that we should be using this medication for COVID-19.”

She said there are only mixed results for the drug’s efficacy, and no drug should be promoted unless it’s scientifically proven to be effective.

Dr. Megan Ranney, an emergency room physician and researcher at Brown University, echoed these remarks in a subsequent interview. She said the president’s advice to Americans made her “nervous” and there is, in fact, a “lot to lose.”

“This medication has major side effects including paranoia, hallucinations, suicidal thoughts, suppression of your blood counts so that you become more susceptible to infections. It can cause severe cardiac arrhythmias that can even cause death,” she said.

“They are not common side effects, but they are common enough that this should not be taken willy-nilly. It is not like water, it is not harmless, and it may have major side effects.”

She said she expected results from clinical trials for the drug to come through in as soon as a month or two.

While the medication is FDA-approved as a treatment for lupus, rheumatoid arthritis and other conditions, federal officials are still investigating its efficacy as a treatment for coronavirus, for which it has not been approved.

Not only could the drug be dangerous to users when taken inappropriately, stockpiling is harming those with existing conditions who depend on the medication.

The AMA has issued a joint statement with the American Pharmacists Association last month advising against the “inappropriate ordering, prescribing or dispensing of medications to treat COVID-19,” warning of “grave consequences” for those who already relied on those drugs.

Fauci, who leads the National Institute of Allergy and Infectious Diseases and is a key member of Trump’s coronavirus task force, has persistently stated the treatment’s benefits are unproven against coronavirus.

“In terms of science, I don’t think we can definitively say it works,” he told CBS’s Face the Nation. “The data are really just at best suggestive. There have been cases that show there may be an effect and there are others to show there’s no effect.”

A small study in China found that patients with mild illness due to COVID-19 were able to recover faster after taking hydroxychloroquine, and other anecdotal reports in China and France also suggested it may help. However, other clinical studies have found it not to be effective.

The results now are conflicting, however, experts say they’ll have more definitive answers after ongoing randomized clinical trials for the potential treatment.