Trump pushes Tylenol warning and leucovorin therapy in autism announcement as NIH review remains incomplete

In a White House briefing on Monday, President Donald Trump urged pregnant people to avoid taking acetaminophen, commonly known as Tylenol, if possible because of a purported link to autism. At the same event, he promoted leucovorin, a decades‑old medication that mimics folic acid and is sometimes used to restore nutrients in patients undergoing chemotherapy. The president said Tylenol should be avoided unless a fever is extremely high, while Health Secretary Robert F. Kennedy Jr. framed the inquiry as part of a broader effort to find the factors behind rising autism diagnoses.

Officials and researchers stressed that the connection between Tylenol and autism remains unclear, and major medical groups still recommend cautious use during pregnancy after consultation with a physician. The link between vaccines and autism has been studied exhaustively, and no connection has been established. The White House has signaled that the NIH is conducting a broad review of autism science, but the assessment was not completed in time for the briefing, according to the Washington Post.

On the Tylenol question, the evidence remains mixed. A systematic review published this year evaluating six studies found an association between acetaminophen use during pregnancy and autism in some cohorts, but the authors cautioned that association does not prove causation and that many included studies were small and observational. The largest study in the review looked at 2.5 million children in Sweden and found no link after adjusting for confounding factors. Critics note that fever itself is a known risk factor for neurodevelopmental issues, making it difficult to disentangle the effects of the medication from the illness being treated.

“The data are not yet born out in the way the administration framed them,” said Stephen Scherer, director of the Center for Applied Genomics at the Hospital for Sick Children in Toronto. He emphasized that “rushed science” can overstate risks and cautioned that discouraging use of Tylenol during pregnancy could itself carry risks for mothers and fetuses. Medical guidelines remain anchored in guidance that acetaminophen can be used for fever or pain during pregnancy after a careful doctor’s assessment.

Beyond Tylenol, the president highlighted leucovorin as a potential therapy for autism. Investigations in small trials have shown limited, preliminary signals that the drug might affect symptoms in some children, but the body of evidence remains scant. One trial involved fewer than 50 patients, and researchers have cautioned that it is far from clear whether any benefit would apply broadly to people on the autism spectrum. Leucovorin’s safety profile is generally favorable in its approved uses, but experts caution that a treatment’s safety does not guarantee universal effectiveness for autism.

The announcement comes as Kennedy and Trump have pressed a public drive to resolve questions about autism, prompting criticism from many scientists and advocates who say the claims outpace the science. The Coalition of Autism Scientists issued a statement saying the data cited by the White House do not support the assertion that Tylenol causes autism or that leucovorin is a cure, and that communicating otherwise risks fueling fear rather than advancing understanding.

The public discussion of autism’s rise has drawn attention to how diagnoses have expanded over time. Government data show a marked increase in diagnosed cases over the past two decades, prompting questions about whether rising prevalence reflects more children being identified, broader definitions, or other factors. The CDC’s historical estimates placed autism diagnoses in the range of about 2 to 7 per 1,000 in the 1990s; modern estimates commonly cite approximately 1 in 35 children, which equates to roughly 3 percent. Experts stress that several elements—greater awareness, improved screening, and evolving diagnostic criteria—likely contribute to higher reported rates rather than a single causative toxin.

Genetics remain a dominant focus for researchers seeking to understand autism’s roots. Multiple studies have attributed a substantial share of risk to inherited factors, with genetics estimated to account for about 80 percent of the variance in susceptibility. While scientists acknowledge that non-genetic factors may play a role—such as older parental age—the search for a single causative environmental agent has not yielded a consensus. Some researchers warn against simplistic explanations that attempt to tie autism to a lone chemical exposure.

The administration’s efforts to frame a clear causal narrative are drawing pushback from researchers who have spent years studying autism. The NIH has undertaken a broad review of autism science, but the timeline for completing that review remains unclear, and some researchers say the public messaging should reflect the preliminary nature of current findings instead of presenting emerging evidence as a settled conclusion. The emphasis on a definitive link or cure—whether through Tylenol avoidance or leucovorin treatment—has raised concerns that policymakers could inadvertently mislead families who are navigating real and complex decisions about care.

As the conversation continues, experts urge careful interpretation of early signals and stress the importance of robust, well‑designed studies to distinguish correlation from causation. In the meantime, clinicians and public health officials say that pregnant people should consult their healthcare providers about the appropriate use of medications for fever or pain and that vaccines remain a critical tool in preventing disease, with no proven link to autism according to current evidence.