The CIA has privately advised its workforce that taking an anti-malarial drug touted by President Trump and some of his supporters as a promising treatment for the novel coronavirus has potentially dangerous side effects, including sudden death.

The warning, featured on a website for CIA employees with questions related to the spread of covid-19, came in late March after public discussion — and promotion by the president — that hydroxychloroquine, administered in concert with the antibiotic azithromycin, might prove effective against the disease.

The politically charged debate over hydroxychloroquine medical experts say there’s no conclusive evidence it does what Trump has suggested — underscores a recurring phenomenon in this administration, in which the president stakes out a very public, sometimes controversial position on a subject only to have agencies within the government chart a different, more cautious approach.

A CIA website for employees with questions about the coronavirus addressed the topic on March 27, noting there had been media reports suggesting the drug “has activity against the COVID-19 virus.”

“At this point, the drug is not recommended to be used by patients except by medical professionals prescribing it as part of ongoing investigational studies. There are potentially significant side effects, including sudden cardiac death, associated with hydroxychloroquine and its individual use in patients need to be carefully selected and monitored by a health care professional,” the answer said, before adding in bold type: “Please do not obtain this medication on your own.”

A CIA spokesman declined to comment about internal workforce communications. The advice was posted as a response after an employee asked whether they should take the drug without a prescription.

The warning came about a week after the president first touted the drug at a White House news conference. “I think it could be, based on what I see, it could be a game changer,” Trump said.

The president became a bigger booster of the drug as the public health crisis worsened, saying at an April 3 briefing that hydroxychloroquine is “looking like it’s having some good results.”

On Monday, the president added: “Just recently a friend of mine told me he got better from the use of that drug, so who knows? . . . I think if anybody recommended it other than me, it would be used all over the place.”​

Trump’s cause has been taken up by some of his supporters, including Fox News personalities Sean Hannity and Laura Ingraham, but medical experts have sounded the same cautious note found in the CIA’s advice to its workforce.

On April 5, as the president’s comments continued to raise alarm among medical experts, Trump added a note of caution to his praise of the drug, saying: “You have to go through your medical people, get the approval. But I’ve seen things that I sort of like. So what do I know? I’m not a doctor. . . . But I have common sense.”

Hydroxychloroquine has been used for decades to treat malaria and has also been used to treat lupus and rheumatoid arthritis. But it’s not clear whether it works for covid-19, the disease caused by the novel coronavirus. Among the few preliminary studies was one showing promise, although that result was subsequently questioned by the study’s publisher.

Experts have cautioned about side effects, such as heart arrhythmia, which can be fatal.

A recent study in Brazil of chloroquine, which is similar to hydroxychloroquine, was halted early because a number of test subjects developed dangerous heart problems.

Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, has said the data on hydroxychloroquine’s effectiveness against the virus is “really just at best suggestive.”

Last month, the Food and Drug Administration gave emergency approval to a Trump administration effort to distribute millions of doses of anti-malarial drugs to hospitals across the country, saying that trying unproven treatments is worth it to slow the disease in seriously ill patients.