The Food and Drug Administration said on Monday that it was revoking emergency authorization of two malaria drugs to treat Covid-19 in hospitalized patients, saying that they are “unlikely to be effective” and could carry potential risks.
The drugs, hydroxychloroquine and chloroquine, were heavily promoted by President Trump after a handful of small, poorly controlled studies suggested that they could work against the disease caused by the coronavirus. Mr. Trump said he took hydroxychloroquine after he had been exposed to two people who tested positive for the coronavirus.
The agency said that after reviewing some data, it determined that the drugs, particularly hydroxychloroquine, did not demonstrate potential benefits that outweighed their risks. Earlier this spring, the F.D.A. had also issued a warning that the drugs could cause dangerous heart arrhythmias in Covid-19 patients.
The review that led to the revocation found more than 100 cases of serious heart disorders in