The U.S. Food and Drug Administration (FDA) issued a warning Friday about the “potentially life-threatening” side effects of using hydroxychloroquine and chloroquine to treat the coronavirus outside of a hospital setting or without doctor supervision. 

The FDA warned there is a possibility for “serious heart-related adverse events and death” in patients who take the drugs to recover from the coronavirus, officially known as COVID-19.

“While clinical trials are ongoing to determine the safety and effectiveness of these drugs for COVID-19, there are known side effects of these medications that should be considered,” said FDA Commissioner Stephen M. Hahn. “We encourage health care professionals making individual patient decisions closely screen and monitor those patients to help mitigate these risks.”

The announcement comes after the drug has been widely promoted through social media and by President Donald Trump, who said the drug had the potential to work as a treatment for the disease that has infected nearly 900,000 Americans in the past few months. 

The agency’s move Friday to warn Americans against taking the drugs without medical supervision comes after weeks of hype about hydroxychloroquine on social media, which led some platforms like Twitter to take sweeping action to remove the misinformation. The drug was even pushed by President Donald Trump, who said the drug had the potential to work as a treatment for the disease that has infected nearly 900,000 Americans in the past few months.

Other government agencies have followed suit in backing off of using hydroxychloroquine to treat COVID-19. The Centers for Disease Control and Prevention (CDC) updated its information page about the drugs and removed its recommendation for dosage, citing a lack of scientific evidence. 

Earlier this month, a Mayo Clinic cardiologist said there is potentially fatal danger in promoting the use of the drug, aiming criticism directly at Trump, who has mentioned them frequently in his daily coronavirus press briefings. 

In March, the FDA made a controversial decision when it authorized chloroquine and hydroxychloroquine to be added to the Strategic National Stockpile. The drugs are better known to treat malaria, and have been found to greatly inhibit a person’s immune system, making them useful to treat autoimmune diseases. 

The FDA said it will continue to monitor clinical trials of the drugs and will allow them to be used in hospital settings.