In September 2025, President Trump and Health Secretary Robert F. Kennedy Jr. urged pregnant women to avoid taking acetaminophen (Tylenol), saying it could increase autism risk in their children. Medical experts quickly disputed that claim, saying the evidence does not support a causal link.
A study published in The Lancet found that orders for acetaminophen for pregnant patients in emergency departments dropped by about 10% in the months after the White House remarks. The decline was specific to pregnant patients; acetaminophen orders did not change for comparable nonpregnant patients. Researchers reached the finding by analyzing electronic health records from more than 1,600 hospitals.
“This happened overnight,” said Dr. Jeremy Faust, an emergency physician at Brigham and Women’s Hospital in Boston who led the study, describing the immediate impact on ED ordering patterns. The analysis could not determine whether the change reflected more patients refusing the drug, clinicians prescribing it less, or a combination of both.
Caleb Alexander, a professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health, said the results were not surprising, noting that statements from high-profile leaders can quickly affect both prescriber and patient behavior. He added it was reassuring that acetaminophen ordering was trending back toward baseline by December, and that sustained changes in prescribing usually require more than a single public statement.
The study also identified a pronounced increase in prescriptions for leucovorin, a B vitamin that the president mentioned as a potential autism treatment. Unlike acetaminophen orders, leucovorin prescriptions had not declined by the end of the study period in early December. Large clinical trials demonstrating leucovorin’s effectiveness for autism have not been conducted.
Tylenol maker Kenvue responded by saying it supports scientific evidence and that there is no credible proof linking acetaminophen to autism. The company reported that Tylenol use rebounded in December. Although the president and his health team discussed updating Tylenol’s label, no label change has occurred.
The Lancet study highlights how public pronouncements by prominent figures can produce rapid shifts in medical use, even when the underlying science remains unsettled. The authors and outside experts emphasize the need for clear communication rooted in established evidence to guide both patients and clinicians.