As Trump ties Tylenol to autism, doctors raise alarms

The Trump administration on Monday ventured into uncertain scientific territory, calling to limit the use of one medication under investigation for a possible connection to autism while pushing to expand access to another being studied as a potential therapy — despite the lack of definitive evidence for either.

“Taking Tylenol is not good,” President Donald Trump said during a briefing at the White House. “I’ll say it. It’s not good.”

U.S. health officials warned that acetaminophen, the active ingredient in Tylenol and more than 600 other medications, should be avoided in early pregnancy except in cases of high fever — a sharp pivot in public health guidance on a medication that many major medical associations, including the American College of Obstetricians and Gynecologists, say is safe. The administration said that the Food and Drug Administration would be updating the drug’s labeling and that a letter would be sent to all physicians in the country.

Trump also highlighted leucovorin — a drug used to treat the side effects of certain cancer medications — as a potential autism treatment. Early trials involving small groups of children have shown encouraging gains in speech. Though researchers emphasize the need for larger studies, the administration said the FDA would move to formally acknowledge the drug’s potential use in autism treatment and ask states to monitor and study its use.

The president called the moves “historic,” but the announcement was met with sharp criticism and concern from doctors, scientists and autism advocates.

Some expressed concerns that the warnings could prompt pregnant individuals to avoid Tylenol even when sick, or could push parents to try leucovorin without proper medical oversight and limited understanding of its effectiveness or long-term risks. But the fears run deeper than medical misuse.

What alarms many in the scientific community is the politicized rush to present these drugs as solutions, bypassing the slow, careful work that research demands. They warn that drawing broad conclusions from incomplete evidence isn’t just premature but reckless. And it risks undermining the public trust that is the foundation of public health.

“It’s wild,” said Colin Killick, executive director of the Autistic Self Advocacy Network. “They are playing loose with facts to show the appearance of a connection rather than doing responsible science.”

Theresa Miskimen Rivera, president of the American Psychiatric Association and chair and clinical professor of psychiatry at Rutgers Robert Wood Johnson Medical School, expressed concern about the mixed messages reaching the public and creating anxiety. Rivera urged individuals to talk with their doctors when deciding whether to take the medication — just as they would with any other drug.

The administration’s announcements are “very, very premature,” she said. “When you do that it’s endangering not only physical health but mental health.”

Trump throughout the event repeatedly warned pregnant women to avoid taking Tylenol and to not give it to newborns, even as he seemed to concede that he was going further than medical advisers and scientists would support. He also said that the research wasn’t robust enough to back up what he was saying because the government in the past had politicized what projects to fund.

“This is based on what I feel,” he said in one instance.

“There’s a rumor — and I don’t know if it’s so or not — that Cuba, they don’t have Tylenol because they don’t have the money for Tylenol,” he said in another. “And they have virtually no autism. Okay?”

He said he was giving “a very strong recommendation” while also saying it was “maybe stronger from me than from the group because they’re waiting for certain studies.”

But he was emphatic in issuing the warning, at one point on the verge of shouting.

“Don’t take Tylenol!” Trump said. “There’s no downside. Don’t take it! You’ll be uncomfortable. It won’t be as easy, maybe. But don’t take it!”

The FDA’s notice offered a more measured take on the possibility of a connection between the drug and autism. It noted that a causal link has not been established, but in the “spirit of patient safety and prudent medicine” it urged clinicians to consider minimizing the use of acetaminophen during pregnancy for routine low-grade fevers.

Kenvue, the company that makes Tylenol, said in a statement Monday that research shows the medication does not cause autism: “The facts are that over a decade of rigorous research, endorsed by leading medical professionals and global health regulators, confirms there is no credible evidence linking acetaminophen to autism.”

Research into a potential link between Tylenol and autism has produced some conflicting findings. The largest study to date — a 2024 analysis published in JAMA that tracked siblings across Sweden — found no evidence of a connection. Yet a comprehensive review released this August, which pooled all existing studies, did uncover a link. Its authors cautioned that it’s too soon to conclude that the medication causes autism, but they did recommend what they called a “precautionary” approach to taking the drug.

“Patients who need fever or pain reduction during pregnancy should take the lowest effective dose of acetaminophen, for the shortest possible duration,” Andrea Baccarelli, one of the authors and a professor of environmental health at the Harvard T.H. Chan School of Public Health, said in a statement.

The autism initiative is a shared brainchild of Trump and Robert F. Kennedy Jr., his secretary of health and human services, with both men long voicing concerns about the rise of autism diagnoses in the U.S. and often invoking debunked claims that the condition is linked to vaccines.

Kennedy in April pledged that his team would know by September “what has caused the autism epidemic” and work “to eliminate those exposures,” sparking skepticism from researchers and former officials who said a five-month timeline was unrealistic given that decades of careful study have not produced definitive answers.

Kennedy has since made autism a key part of his “Make America Healthy Again” agenda, with his deputies launching a high-stakes, politically charged research effort to uncover the causes of autism. Public health experts, Democrats and some Republican senators have warned Kennedy not to resurrect discredited claims about vaccines.

The administration’s autism event was set to focus on the potential role of Tylenol and leucovorin in either causing or treating the condition — already controversial ideas, but ones that eschewed the fraught vaccine politics that many Republicans, including the president’s pollster, have warned could harm the party.

But at several points during the event, Trump ventured into the subject, urging Americans to not give the hepatitis B vaccines to babies and to “break it up” by taking different vaccines at different times — an approach that is not recommended by medical groups.

“Don’t let them pump your baby up with the largest pile of stuff you’ve ever seen in your life, going into the delicate little body of a baby,” he said.

A report on autism led by the National Institutes of Health, expected to be a centerpiece of the administration’s work, is not yet complete, with researchers expected to review several dozen hypotheses related to the condition, according to two officials who spoke on the condition of anonymity to discuss deliberations that were in progress.

Officials said the lead-up to Trump’s rushed announcement was far choppier than some of the carefully choreographed government health rollouts, which can be months or years in the making.

Federal officials last week battled over what would be in Monday’s announcement, how strongly to tout their findings and whether to even brief reporters, according to two people who spoke on the condition of anonymity to describe internal discussions.

A notice in the Federal Register, saying that the FDA would be approving a branded version of leucovorin, was posted prematurely Monday morning, a health department official said, before government officials withdrew it.

HHS did not respond to a request for comment on internal disagreements about the autism initiative.

But the president’s eagerness outweighed his deputies’ reticence, with Trump hinting on Friday that an autism announcement was forthcoming. “I don’t want to wait any longer,” Trump said Saturday night, teasing the upcoming announcement. “Got to be Monday. I don’t want to do it Tuesday, Wednesday, Thursday.”

Administration officials said they were in talks with companies about increasing supplies of leucovorin. GSK, which held a patent for a brand-name version of leucovorin before it expired, confirmed Monday that it had been asked by the administration to submit a supplemental new drug application to update the label to include an indication for the treatment of a type of folate deficiency linked to autism.