US President Donald Trump has again defended the use of hydroxychloroquine to ward off coronavirus, contradicting his own public health officials.
He argued the malaria medication was only rejected as a Covid-19 treatment because he had suggested it.
His remarks come after Twitter banned his eldest son for posting a clip touting hydroxychloroquine.
There is no evidence the drug can fight the virus, and regulators warn it may cause heart problems.
Last month, the US Food and Drug Administration (FDA) cautioned against the use of the drug for treatment of the coronavirus, following reports of "serious heart rhythm problems" and other health issues.
The FDA also revoked its emergency-use authorisation for the drug to treat Covid-19. The World Health Organization (WHO) says "there is currently no proof" that it is effective as a treatment or prevents Covid-19.
Studies commissioned by the WHO, the US National Institutes of Health and other medical researchers around the world have found no evidence that hydroxychloroquine - when used with or without the antibiotic azithromycin, as repeatedly recommended by President Trump - helps treat coronavirus.
Hydroxychloroquine was first touted by Mr Trump in March in relation to Covid-19.
The president told reporters at the White House on Tuesday: "When I recommend something, they like to say 'don't use it.'"
Mr Trump, 74, surprised reporters in May by saying he had begun taking the unproven medication.
On Tuesday, he said: "I can only say that from my standpoint, and based on a lot of reading and a lot of knowledge about it, I think it could have a very positive impact in the early stages.
"I don't think you lose anything by doing it, other than politically it doesn't seem too popular."
President Trump and his son Donald Trump Jr were among social media users who shared video late on Monday of a group called America's Frontline Doctors advocating hydroxychloroquine as a Covid-19 treatment.
Facebook and Twitter removed the content, flagging it as misinformation, but not before more than 17 million people had seen one of the clips.
Twitter also banned the US president's eldest son from tweeting for 12 hours as a penalty for sharing the clip.
The video in question showed doctors speaking outside the US Supreme Court at an event organised by Tea Party Patriots Action, a group that is not required to disclose its donors and has helped fund a pro-Trump political action committee.
In the video, Dr Stella Immanuel, a physician from Houston, says she has successfully treated 350 coronavirus patients "and counting" with hydroxychloroquine.
The president said on Tuesday: "I think they're very respected doctors. There was a woman who was spectacular in her statements about it."
According to the Daily Beast, Dr Immanuel has previously claimed the government is run by "reptilians" and that scientists are developing a vaccine to stop people being religious, among other bizarre views.
America's Frontline Doctors' founder Simone Gold accused social media companies of censorship for removing the hydroxychloroquine video.
"Treatment options for COVID-19 should be debated, and spoken about among our colleagues in the medical field," she tweeted. "They should never, however, be censored and silenced."
Late on Monday, Mr Trump also retweeted several tweets critical of Dr Anthony Fauci, a leading member of the White House coronavirus task force.
But in Tuesday's briefing the president denied he was criticising the director of the National Institute for Allergy and Infectious Diseases, insisting: "I get along with him very well."
Asked about hydroxychloroquine earlier on Tuesday, Dr Fauci said the medication was not an appropriate treatment for Covid-19.
He told ABC News' morning show the drug was "not effective in coronavirus disease".