The agency reversed its authorization after being asked to do so by Gary Disbrow, acting director of the Biomedical Advanced Research and Development Authority (BARDA).
Based on recent trials, scientists at the FDA believe hydroxychloroquine and chloroquine, also known as HCQ and CQ, "are unlikely to produce an antiviral effect."
It is no longer reasonable to believe that hydroxychloroquine and chloroquine may be effective in treating COVID-19, Hinton said.
Rescinding the order "means that the supply of the drug stuck in the stockpile is now free from the EUA's restrictions, once it is released into the consumer supply chain," it added.
Clinical trials, more rigorous than observational studies, are underway in the UK, the United States, and in other countries testing the efficacy and safety of hydroxychloroquine and chloroquine.
The drugs were approved decades ago for use against ailments including malaria. They were used early during the pandemic in treatment of patients with the CCP virus, and doctors around the world said they worked against the disease.
The use of the drugs became a political issue when they were endorsed by President Donald Trump. Some of his critics quickly made hyperbolic claims and later circulated observational studies indicating the drugs aren't effective against COVID-19.
While some studies have pointed to a lack of effectiveness in certain dosages and certain populations, others, including ones conducted in France and the United States, indicate the drug might be effective in some cases, especially when combined with azithromycin, an antibiotic, and zinc.
The FDA issued the authorization in March, but the next month it warned against using the drugs outside of hospitals or clinical trials because of side effects including heart issues.
BARDA, an office inside the Department of Health and Human Services, has had a large impact on policy concerning hydroxychloroquine.
Dr. Rick Bright, who headed the office, initially requested the emergency-use authorization, but later filed a whistleblower complaint alleging concerns he put forth about the drug were downplayed or ignored.
Disbrow replaced Bright after the doctor was shifted to the National Institutes of Health.