The U.S. Food and Drug Administration is warning doctors against prescribing a malaria drug widely touted by President Donald Trump for treating the new coronavirus outside of hospitals or research settings.

In an alert Friday, regulators flagged reports of serious side effects and death among patients taking hydroxychloroquine and the related drug chloroquine. The drugs, also prescribed for lupus, can cause a number of side effects, including heart rhythm problems, severely low blood pressure and muscle or nerve damage.