This post was updated Oct. 12 at 9:22 p.m.

UCLA experts and medical professionals warned that unproven claims made by the White House linking the use of Tylenol during pregnancy to the development of autism promotes misinformation.

President Donald Trump and Health and Human Services Secretary Robert F. Kennedy Jr. announced that the Food and Drug Administration plans to update the safety label for acetaminophen – an over-the-counter pain reliever commonly known as Tylenol – in a Sept. 22 press conference. Throughout the conference, officials repeatedly linked use of the drug during pregnancy to the development of autism – a neurodevelopmental condition that can affect motor skills, language, sensation, perception and executive functioning on a spectrum, according to the Autistic Self Advocacy Network.

The American College of Obstetricians and Gynecologists condemned the Trump administration’s claim that same day, calling it “irresponsible when considering the harmful and confusing message they send to pregnant patients, including those who may need to rely on this beneficial medicine during pregnancy.”

The characterization of autism as a problem that needs to be erased can be a distressing message for those identifying with the diagnosis, said Shulamite Green, an assistant professor in UCLA’s Department of Psychiatry and Biobehavioral Sciences. She added that these claims about Tylenol usage are dismissive to the decades of expert research attempting to find potential causes.

Green said the rhetoric used by the Trump administration is harmful because it harkens back to prior theories where mothers were blamed for their children’s autism. One such line of thinking originating in the 1970s held that a “refrigerator mother,” who did not show their children adequate affection, caused their children’s conditions, according to Britannica.

“Even people who are very knowledgeable, it’s hard not to hear the president say these things and start to question, ‘Did I do something?’” Green said. “’Did I take Tylenol? Did I cause this?’”

Dr. Beate Ritz, a professor of epidemiology at the UCLA Fielding School of Public Health, coauthored a review of the epidemiological research cited by the Trump administration that declared a causal link between Tylenol and neurodevelopmental disorders. The review found that 27 out of 46 studies on the relationship reported positive associations, according to the abstract published in the scientific journal Environmental Health.

This research does not prove causation, Ritz said. However, there are still some unknown risks for all people who take Tylenol, she added.

“We would want to get doctors to at least acknowledge that Tylenol is not like candy,” she said. “You can’t just say it is completely riskless.”

Confounding variables – such as underlying health conditions leading to increased painkiller usage – could also be at play, and determining that would be complicated to decipher, Ritz said. Complications due to untreated chronic pain associated with pregnancy can also pose risks to mothers, she added.

During the press conference, Trump told people experiencing pain during pregnancy to “tough it out” and avoid taking the medication. The FDA also announced it plans to file a federal register notice to change the label on leucovorin – a synthetic form of folate, a vitamin important for DNA repair and blood cell synthesis – so it can be prescribed to children with autism.

A press release by the HHS claimed cerebral folate deficiency is linked to autism and the move to edit leucovorin’s label constitutes the “first FDA-recognized therapeutic for children with cerebral folate deficiency and autistic symptoms.”

Most existing studies on the effects of leucovorin are not randomized and placebo-controlled – the “gold standard” for drug testing, Green said. Only two studies of the drug as a treatment for autism met these criteria, and neither provided strong evidence of leucovorin’s effectiveness, she added.

Additionally, a 2024 meta-analysis found that sibling-controlled studies – in which children from the same mother with different levels of prenatal Tylenol exposure are compared – did not find links between the drug and autism, Green said.

The identified prevalence of autism spectrum disorder has risen from around one in 150 children in 2000 to one in 31 children in 2022, according to data from the U.S. Centers for Disease Control and Prevention. Throughout the conference, Kennedy promised to uncover the causes of rising autism diagnoses, which he called an “alarming trend” and an “epidemic.”

Officials at the press conference also announced 13 projects focusing on “exposomics” – described by National Institutes of Health Director Jay Bhattacharya as a new kind of science studying the interplay between “environmental and medical factors” and “biology and genetics” on the causes of autism. It will be funded by the Autism Data Science Initiative, with Kennedy denouncing prior genetic research as “politically safe and entirely fruitless.”

Enhanced awareness and understanding of autism as a spectrum, as well as the expansion of services for those with the diagnosis have contributed to this uptick in autism diagnoses, said Catherine Lord, a distinguished professor of psychiatry and education at the UCLA David Geffen School of Medicine. Diagnostic rates are increasing in areas with more services for those with autism diagnoses – irrespective of acetaminophen usage – Lord added.

Lord said the Trump administration’s new initiative is “ironic” in that the studies it funds are similar to those the Trump administration has pulled funding from.

“They’re just giving the money back to the same people that have had it all along – which are the geneticists – because they’re doing the research that most easily fits into our research model,” Lord said.

Public health is best served when groups of experts collaborate to determine beneficial courses of action, which requires physicians, scientists and the public to trust each other, Ritz said.

“I hope politics doesn’t get in the way of good science and expert opinion and decision making,” Ritz said. “When it does get in the way, people will be harmed.”