Donald Trump has told reporters at the White House that for “a couple weeks” he has been taking a malaria drug as a defense against Covid-19 – despite warnings from his administration that it is dangerous.

Trump said he was taking hydroxychloroquine – a drug approved to treat malaria, lupus and rheumatoid arthritis – in response to the coronavirus threat.

But the Food and Drug Administration (FDA) has been warning since April that the drug should not be used for that purpose because it could cause irregular heartbeats and other cardiac trauma.

The drug is not approved as a treatment for Covid-19 and Trump has not been diagnosed with the disease, to public knowledge.

Trump’s claim to be taking the drug was made as he attacked an administration whistleblower who went before Congress last week and described internal pressure to endorse the drug as an effective coronavirus treatment.

The whistleblower, Rick Bright, was the former director of a federal agency in charge of vaccines.

On Monday, Trump called Bright a hypocrite and then riffed on the supposed benefits of the drug, which the FDA advised has “not been shown to be safe and effective for treating or preventing Covid-19”.

“You’d be surprised at how many people are taking it … The front line workers many many are taking it,” Trump said.

“I happen to be taking it. I happen to be taking it. I’m taking it, hydroxychloroquine. Right now, yeah. A couple weeks ago I started taking it. Because I think it’s good, I heard a lot of good stories… I take a pill every day.”

Previously, Trump had endorsed the injection of disinfectants or light into the body to fight coronavirus – recommendations that were followed by a spike in calls to poison control centers.

But Trump had never before claimed to be trying one of the home remedies himself.

A string of studies around the world have suggested that hydroxychloroquine or chloroquine do little to prevent or treat Covid-19, and the FDA has cautioned against the use of either drug for Covid-19 outside of the hospital setting or a clinical trial “due to risk of heart rhythm problems”.

The drugs “can cause abnormal heart rhythms such as QT interval prolongation and a dangerously rapid heart rate called ventricular tachycardia,” the FDA said.

Dr Anthony Fauci, the country’s top infectious disease doctor and a member of the White House coronavirus taskforce, has repeatedly warned that there is no conclusive evidence to support using the drug.

The United States passed two grim milestones for coronavirus cases on Monday, surpassing 1.5m confirmed cases and 90,000 deaths, according to numbers recorded by Johns Hopkins University.

Trump touted hydroxychloroquine as a potential coronavirus treatment in March, a claim that was amplified for weeks on Fox News. But alarming reports in April about the health risks tied to the drug silenced that talk until the Bright episode.

Bright, the former director of the Biomedical Advanced Research and Development Authority, told Congress last week that he was removed from his post after resisting pressure by the administration to make “potentially harmful drugs widely available”, including chloroquine and hydroxychloroquine.

The FDA has issued repeated warnings about the dangers of the drugs in question.

“While clinical trials are ongoing to determine the safety and effectiveness of these drugs for Covid-19, there are known side effects of these medications that should be considered FDA commissioner Stephen M Hahn said in a statement issued in late April. “The FDA will continue to monitor and investigate these potential risks and will communicate publicly when more information is available.”

By user