(Reuters) – The National Institutes of Health (NIH) said on Thursday it was testing anti-malaria drug hydroxychloroquine for treating COVID-19, days after several U.S. doctors said they were using the drug on infected patients without evidence that it worked.

The use of the decades-old drug, which has been touted by President Donald Trump as a potential weapon against COVID-19, has soared as the United States has quickly become the epicenter of the pandemic.

The study will evaluate the safety and the effectiveness of hydroxychloroquine and be conducted by the National Heart, Lung, and Blood Institute (NHLBI), part of NIH.

“Hydroxychloroquine has showed promise in a lab setting against SARS-CoV-2, the virus that causes COVID-19, and preliminary reports suggest potential efficacy in small studies with patients,” said James P Kiley, director, Division of Lung Diseases, NHLBI.

The drug is used to treat malaria and rheumatoid conditions such as arthritis. Potential side effects of the drug include vision loss and heart problems.

The U.S. Food and Drug Administration has not approved hydroxychloroquine as a COVID-19 treatment, but it has provided an emergency use authorization for the anti-malaria drug.

Drugmakers across the world are racing to develop a treatment or a vaccine for the disease that has killed over 87,000 people.

(Reporting By Mrinalika Roy in Bengaluru; Editing by Shinjini Ganguli)