Health experts have pushed back against comments by President Donald Trump suggesting that acetaminophen use during pregnancy could cause autism, warning that such statements risk misleading the public without scientific basis.
Speaking at a White House event on Sunday, Trump said women should avoid taking acetaminophen, the active ingredient in Tylenol, unless “medically necessary.”
He argued that “taking Tylenol is not good,” and added, “They are strongly recommending that women limit Tylenol used during pregnancy unless medically necessary. That’s, for instance, in cases of extremely high fever that you feel you can’t tough it out.”
Trump also announced that the Food and Drug Administration (FDA) would begin advising pregnant women of potential risks. In addition, he and Health and Human Services Secretary Robert F. Kennedy Jr. promoted leucovorin, a cancer drug, as a possible therapy for autism in some children.
Kennedy said during the briefing: “Peer-reviewed literature has documented that up to 60 percent of folate-deficient children with ASD can have improved verbal communications if given leucovorin. I have instructed NIH, FDA, and CMS doctors to treat children appropriately.”
Medical experts have questioned both claims. Alycia Halladay, chief science officer at the Autism Science Foundation, said existing research does not support an association between acetaminophen and autism.
“The scientific studies that have been conducted so far do not support the idea that Tylenol causes autism,” she said. “There were two very large studies that used what is known as a sibling control, which controls for genetic background, and they did not see an association.”
Halladay noted that one of the studies mentioned by administration officials — conducted in Boston — was small and did not measure acetaminophen exposure during pregnancy.
“It only looked at acetaminophen exposure at the time of birth. I’m not entirely swayed by that being the source of evidence,” she said.
Jennifer Nuzzo, an epidemiologist at Brown University’s School of Public Health, said untreated fever in pregnancy can itself be harmful and that the president’s advice lacked nuance.
“Simply telling women to avoid it is just not the kind of nuanced, evidence-based advice that pregnant women deserve,” she said. “Nothing that I heard should be interpreted as medical advice. Pregnant women should be talking to their providers about how to manage fever. Leaving it untreated might be detrimental.”
Nuzzo also criticised the administration’s public messaging.
“Pregnancy and autism are very serious medical issues that require evidence. Nothing that has been done by this administration has produced the sort of evidence required to establish these links,” she said. “It’s really strange and disheartening that we might be cherry-picking low-quality evidence and holding a national presidential press conference.”
The experts also addressed Trump’s renewed suggestion that vaccines are linked to autism, a claim long rejected by researchers.
“Vaccines have actually been the number one most studied environmental factor in the causes of autism,” Halladay said. “It has been studied dozens of times across the world in different populations. There has been no credible evidence to link vaccine administration to autism.”
On leucovorin, Halladay cautioned that there is not yet sufficient data to recommend it broadly for children with autism.
“We have absolutely no safety data on this drug in children with autism,” she said. “A couple of small studies suggest it could be helpful in some situations, but they have not been replicated. There are a lot of questions to be answered before anyone recommends it.”