(HealthDay)—The use of the antimalarial drug chloroquine to treat COVID-19 patients has been halted at several Swedish hospitals due to reported side effects such as cramps and loss of peripheral vision. Sahlgrenska University Hospital is one of those facilities. It stopped the use of chloroquine in the treatment of COVID-19 about two weeks ago.

“There were reports of suspected more serious side effects than we first thought,” Magnus Gisslen, M.D., Ph.D., a professor and chief physician at Sahlgrenska University Hospital infection clinic, told the Gothenburg Post on April 1, Newsweek reported. “We cannot rule out serious side effects, especially from the heart, and it is a hard-dosed drug. In addition, we have no strong evidence that chloroquine has an effect on COVID-19.”

No specific drugs are used to treat COVID-19, but some people have advocated the use of the antimalarial drugs chloroquine and hydroxychloroquine. U.S. President Donald Trump has touted the use of hydroxychloroquine in particular and announced Sunday that the federal government had stockpiled 29 million hydroxychloroquine pills for the treatment of COVID-19, Newsweek reported.

The use of hydroxychloroquine to treat COVID-19 was approved last month by the U.S. Food and Drug Administration, even though scientific studies of the two antimalarial drugs have yielded mixed results, Newsweek reported.

As of Tuesday afternoon, there were 383,256 COVID-19 cases and more than 12,000 deaths reported in the United States, according to Johns Hopkins University.