Australian health experts have warned of “serious health consequences” if people believe US President Donald Trump’s claim that rising rates of autism are linked to pregnant women taking common paracetamol.

In an extraordinary news conference at the White House on Monday (local time), Trump delivered medical advice not to use or administer the over-the-counter painkiller, which is sold as Tylenol in the US.

Tylenol is an American brand of paracetamol and has the same main ingredient, acetaminophen.

Trump also suggested leucovorin, a form of folic acid, could be a treatment for autism symptoms.

The advice from Trump, who has no medical training and also pointed out, “I’m not a doctor”, goes against that of medical societies, which cite data from numerous studies showing acetaminophen plays a safe role in the well-being of pregnant women.

He said the US Food and Drug Administration would notify doctors that using Tylenol during pregnancy could be associated with a very increased risk of autism, without presenting evidence for the claim.

The US Food and Drug Administration has moved to change acetaminophen product labels while issuing a letter to physicians to say the decision to take it “still belongs with parents”.

Margie Danchin, a clinician scientist at the University of Melbourne and Murdoch Children’s Research Institute, said the claim was based on research that wasn’t robust.

“It’s not a clinical trial, it wasn’t a randomised study, it wasn’t even prospective,” the Royal Children’s Hospital consultant pediatrician told AAP on Tuesday.

“It’s very concerning … it’s going to have serious health consequences.”

Danchin acknowledged trust in health advice had been “damaged” by vaccine mandates during the COVID-19 pandemic, with people finding conflicting information wherever they turned.

“We’re living in very scary times,” she said.

“We need to stand up now as doctors, healthcare providers and scientists to clearly communicate the science … to counteract the sticky mis and disinformation.”

Autism Awareness Australia chief executive Nicole Rogerson described the US administration’s announcement as “jazz hands and nonsense”.

The unfounded claims from the leader of the free world couldn’t be laughed off, she said.

“There will be people here who listen to that who fall hook, line and sinker,” Rogerson said.

She said the president’s suggestion that leucovorin, a form of folic acid, as a treatment for autism symptoms gave off “Ivermectin vibes”, referring to Trump endorsing the unproven use of the drug for COVID-19.

“There is no known evidence that this is a legitimate treatment,” she said.

“He is feeding the world of the conspiracy theorists.”

Australia must double down on stressing the safety of vaccines and cannot “fall asleep” on dispelling misinformation coming out of the United States.

“Sensible people in the scientific community and the government need to be on the front foot here debunking this kind of nonsense,” she said.

There has been no change in advice on the safety of paracetamol from Australia’s Therapeutic Goods Administration following the White House media event.

“Paracetamol remains Pregnancy Category A in Australia, meaning that it is considered safe for use in pregnancy,” a TGA spokesperson said.

“The TGA has no current active safety investigations for paracetamol and autism, or paracetamol and neurodevelopmental disorders more broadly.”

Trump was standing next to Health Secretary Robert F. Kennedy jr, a vaccine critic who has argued that no vaccine is safe, and called for a re-examination of a link between vaccines and autism, a theory that has been repeatedly debunked, and a series of changes not grounded in science.

“Taking Tylenol is not good. I’ll say it. Not good,” he said.

“You shouldn’t give the child a Tylenol every time he gets a shot.

“Fight like hell not to take it. There may be a point where you have to, and that you’ll have to work out with yourself, so don’t take Tylenol.”

Tylenol is made by consumer health company Kenvue, which was spun off from Johnson & Johnson in 2023. The company said it disagreed with the suggestion of a link, which it said was not based in science.

“We believe independent, sound science clearly shows that taking acetaminophen does not cause autism. We strongly disagree with any suggestion otherwise and are deeply concerned with the health risk this poses for expecting mothers,” Kenvue said ahead of Trump’s announcement.

Australia’s Health Minister Mark Butler cautioned pregnant women not to take action without seeking medical advice, noting paracetamol was an important treatment for fever.

Andrew Whitehouse, a professor of autism research at The University of Western Australia, said any “small associations” must be weighed against the risk of untreated high fever for the mother and developing baby.

Senior lecturer at Monash University’s Turner Institute for Brain and Mental Health Hannah Kirk said some studies reported an association between acetaminophen use and autism but “association does not mean causation”.

That conclusion was echoed by Australian Medical Association president Danielle McMullen.

“I wish we had an answer for what causes autism for the many families out there who are struggling,” Dr McMullen told ABC Radio.

“But, in fact, there’s no study that shows that paracetamol is a cause.”

The Trump administration has been under immense pressure from Kennedy’s Make America Healthy Again movement to provide answers on the causes of the marked increase in autism cases in the US in recent years.

Experts say the rise in cases is mainly due to a new definition for the disorder that includes mild cases on a “spectrum” and better diagnoses. They say there is no single cause to the disorder and say the rhetoric appears to ignore and undermine decades of science into the genetic and environmental factors that can play a role.

-with AAP