The decision allows companies to donate supplies of two related drugs — hydroxychloroquine and chloroquine — to the Strategic National Stockpile. The drugs will then be distributed to hospitals for use in patients who have coronavirus. The generic drug maker Sandoz, a division of Novartis, donated 30 million pills of hydroxychloroquine and Bayer donated one million doses of chloroquine. Other companies are ramping up their production of the drugs and may donate more supplies, the federal government said.

Teva has also said it is donating six million pills of hydroxychloroquine to be used in U.S. hospitals.

Mr. Trump has frequently touted the use of the drugs, describing them as a potential “game changer” in the pandemic, although there is only anecdotal evidence that they are effective. Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, and other experts, have been far more cautious in saying that evidence is still needed to know if they work.

However, since there are no treatments for the virus, many hospitals are already using the drugs on severely ill patients. The drugs have been on the market for decades and one, hydroxychloroquine, is also used for lupus and rheumatoid arthritis.

The decision by the F.D.A., issued on Saturday but announced by the Department of Health and Human Services on Sunday, will allow hospitals to use the drugs on patients when enrolling them in clinical trials is not possible. Doctors must report on how they were used, including documenting any harmful side effects. Patients and doctors will also receive a fact sheet explaining that the drug’s efficacy in treating coronavirus is not known.

By restricting hospital use of the drugs to those taken from the national stockpile, the move also eases pressure on the rest of the supply chain. Both drugs have recently gone into shortage, making it difficult for patients who rely on them for other conditions to get access.

Massachusetts veterans’ home sees a rash of deaths.

Eleven residents of a veterans’ home in Massachusetts have died, including five people who tested positive for the coronavirus, a state agency announced on Monday, in another example of how the virus can spread in a facility for vulnerable residents.