WASHINGTON (AP) — The U.S. Food and Drug Administration on Friday warned doctors against prescribing a malaria drug touted by President Donald Trump for treating the new coronavirus except in hospitals and research studies.

In an alert, regulators flagged reports of sometimes fatal heart side effects among coronavirus patients taking hydroxychloroquine or the related drug chloroquine. The decades-old drugs, also prescribed for lupus and rheumatoid arthritis, can cause a number of side effects, including heart rhythm problems, severely low blood pressure and muscle or nerve damage.

The warning...