Alarmed by a growing cache of data linking the anti-malaria drug to serious cardiac problems, some drug safety experts are now calling for even more forceful action by the government to discourage its use. Several have called for the FDA to revoke its emergency use authorization, given hydroxychloroquine’s documented risks.

“They should say, ‘We know there are harms, and until we know the benefits, let’s hold off,’ ” said Joseph Ross, a professor of medicine and public health at Yale University, who added that the original authorization may have been warranted but new evidence has emerged about the drug’s risks.

“I’m surprised it hasn’t been revoked yet,” said Luciana Borio, who served as director for medical and biodefense preparedness of the National Security Council and was acting chief scientist at the FDA.