"The Executive Group has implemented a temporary pause of the hydroxychloroquine arm within the Solidarity Trial while the safety data is reviewed by the Data Safety Monitoring Board," WHO Director-General Tedros Adhanom Ghebreyesus told reporters at a news briefing.
"The other arms of the trial are continuing," Tedros said. "This concern relates to the use of hydroxychloroquine and chloraquine in Covid-19. I wish to reiterate that these drugs are accepted as generally safe for use in patients with autoimmune diseases or malaria."
Hydroxychloroquine, which Trump has repeatedly touted as a potential game changer in fighting the coronavirus, is an anti-malarial drug that's also used by doctors to treat rheumatoid arthritis and lupus.
Numerous clinical trials are looking to see if it's effective in fighting Covid-19, but it is not a proven treatment.
But despite the lack of scientific evidence presenting hydroxychloroquine as a viable coronavirus treatment option, Trump told reporters earlier this month that he has been taking the drug to avoid contracting the disease.
"I happen to be taking it," Trump said during a roundtable event at the White House.
"A lot of good things have come out. You'd be surprised at how many people are taking it, especially the front-line workers. Before you catch it. The front-line workers, many, many are taking it."
The White House declined to comment. The Department of Health and Human Services did not immediately respond to a request for comment from CNBC.
The outbreak has spread to dozens of countries, with more than 5.4 million confirmed cases worldwide and over 345,059 deaths, according to data from Johns Hopkins University. There are at least 1.6 million cases in the United States and at least 97,000 deaths, according to the latest tallies.