Even Steve Doocy had to admit it wasn’t a great idea.
The morning after President Trump mused at a nationally televised briefing that injecting disinfectant could be a treatment for Covid-19 patients, Mr. Doocy, a co-host of “Fox & Friends,” issued a warning to his Fox News viewers.
Injecting disinfectants “is poisonous,” Mr. Doocy said, holding up his hands for emphasis, during an otherwise upbeat segment that praised Mr. Trump for his other health tip: Get more sunlight. (The guest, Dr. Mehmet Oz, did not address the disinfectant idea.)
It was a rare fissure between the president and “Fox & Friends,” a show that regularly praises him. But Mr. Doocy was not the only Fox personality who was unimpressed by the notion that Americans would consider the internal use of disinfectant, which can result in serious injury and death.
“Please don’t try this at home,” said the Fox Business anchor Stuart Varney, one of Mr. Trump’s favorite hosts. The anchor Chris Wallace — not a Trump favorite — felt the need to clarify on-air: “The answer is no, it’s not safe. A lot of the major manufacturers say it isn’t.”
When Mr. Trump made an effort to walk back his remarks on Friday, claiming to reporters at the White House that he had made the comment “sarcastically,” John Roberts, Fox News’s chief White House correspondent, did not sound convinced.
“I was watching very closely,” Mr. Roberts, who attended the briefing, said on the air. “At no time did I seem to think that the president was sarcastically asking the question.”
Bret Baier, Fox News’s chief political anchor, also had a skeptical take. “No one at home thinks, ‘Oh, you know what? I’m going to go drink bleach,’” Mr. Baier said, adding, after a pause, “I don’t think.”
“But it is something that he clearly stepped in here,” Mr. Baier added.
Still, Mr. Trump’s defenders in Fox News prime time, the channel’s most closely watched portion of day, sidestepped the matter entirely on Thursday.
“The drive-by media is attempting to persuade and convince people that Donald Trump told people to drink Drano at the White House press briefing,” the radio host Rush Limbaugh said dismissively on his Friday show. “That Donald Trump told people to go out and get a syringe and inject Clorox in their arms, and that this could be dangerous.”
Here is what Mr. Trump said at Thursday’s briefing: “I see the disinfectant that knocks it out in a minute, one minute. And is there a way we can do something like that by injection inside, or almost a cleaning? Because you see it gets inside the lungs, and it does a tremendous number on the lungs, so it would be interesting to check that.”
Joel B. Pollak, the senior editor at large at Breitbart News, wrote about that statement in a column that ran under the headline “Fact Check: No, Trump Didn’t Propose Injecting People With Disinfectant.”
“Trump used the word ‘inject,’ but what he meant was using a process — which he left ‘medical doctors’ to define — in which patients’ lungs might be cleared of the virus,” Mr. Pollak wrote. (Breitbart later retracted its “fact check” headline, saying the column “should have been framed as an opinion piece.”)
The White House press secretary, Kayleigh McEnany, issued a statement on Friday accusing the news media of taking Mr. Trump’s words “out of context.” That was before Mr. Trump claimed that he had spoken “sarcastically,” to get a rise out of journalists.
Neil Cavuto, a Fox host who has been critical of Mr. Trump, was not impressed with that excuse. “I think it’s important on the president to say and come out unequivocally: ‘Some of you took me seriously, even though I sounded serious saying it. Please do not. Please do not even consider injecting some of this stuff into your system,’” Mr. Cavuto said during a Friday appearance on Fox Business.
It was not the first time that Mr. Trump has offered medical advice on how to combat the virus. For weeks, he touted the use of a malaria drug, hydroxychloroquine, from behind a lectern with the presidential seal.
The drug also had champions on Fox News, particularly Laura Ingraham, one of the network’s prime-time stars, who has relentlessly promoted the drug on her program as a potential cure for the coronavirus. Ms. Ingraham went as far as to meet with Mr. Trump in the Oval Office to pitch him on the medicine.
On Friday, the Food and Drug Administration issued a formal warning against the use of hydroxychloroquine in treating the virus, citing a risk of serious heart rhythm problems. The agency urged that the drug be taken only in a clinical trial or under close supervision in a hospital.
Ms. Ingraham devoted a lengthy segment of her Wednesday program to dismissing the results of a study of Veterans Affairs patients showing that the use of hydroxychloroquine was associated with an increased risk of death. She criticized “this blind obsession to disprove the effectiveness of a drug that is being used right now, tonight, in medical centers across America.”
On Friday, after the F.D.A. issued its warning, Ms. Ingraham retweeted several online articles extolling the use of hydroxychloroquine as an effective treatment.