By that evening, first-time prescriptions of the drugs — chloroquine and hydroxychloroquine — poured into retail pharmacies at more than 46 times the rate of the average weekday, according to an analysis of prescription data by The New York Times. And the nearly 32,000 prescriptions came from across the spectrum — rheumatologists, cardiologists, dermatologists, psychiatrists and even podiatrists, the data shows.

While medical experts have since stepped up warnings about the drugs’ possibly dangerous side effects, they were still being prescribed at more than six times the normal rate during the second week of April, the analysis shows. All the while, Mr. Trump continued to extol their use. “It’s having some very good results, I’ll tell you,” he said in a White House briefing on April 13.