Federal health officials are poised to release a new report suggesting a connection between rising autism rates and the use of acetaminophen, the active ingredient in common painkillers like Tylenol. While scientists have explored this potential link for years, existing research has largely produced inconclusive results.
President Trump himself weighed in, telling reporters on Sunday that he believes acetaminophen is “a very big factor.” The administration intends to issue a warning for pregnant women, advising against acetaminophen use unless absolutely necessary for fever. Mr. Trump emphasized a precautionary approach, stating, “If there’s a question — even if there’s a question — you just do it right?” He is expected to make a formal announcement from the White House later today.
Acetaminophen has traditionally been considered one of the safer options for pain and fever during pregnancy, though doctors routinely caution against prolonged use.
Beyond the acetaminophen warning, the report is also anticipated to recommend leucovorin, a form of the B vitamin folate, as a potential treatment for autism. Folate has long been recognized for its role in neural development.
Despite long-standing concerns about acetaminophen and childhood developmental issues, the scientific consensus remains that autism is a complex condition influenced by a myriad of genetic and environmental factors, not a single cause.
This federal report follows a recent review published just last month. Conducted by epidemiologists from Harvard T.H. Chan School of Public Health and the Icahn School of Medicine at Mount Sinai, that review “found evidence” suggesting a link between acetaminophen use during pregnancy and neurodevelopmental disorders such as ADHD and autism.
However, studies examining the potential risks to fetal brain development have presented mixed findings, with some indicating a link to neurodevelopmental disorders and others finding no such connection.
Major health organizations, including the Food and Drug Administration, the European Medicines Agency, and the Society for Maternal-Fetal Medicine, have all reviewed the available evidence and concluded that the findings are currently inconclusive.
While some scientists have advocated for a cautious approach, urging health professionals to warn pregnant women about a possible link between acetaminophen and autism, specialists in maternal-fetal medicine disagree. They argue that existing guidelines — which advise judicious use of Tylenol and other acetaminophen-containing drugs during pregnancy — are sufficient. Their primary concern is that overly strong warnings might lead women to avoid necessary acetaminophen treatment.
“There’s no credible scientific link that Tylenol causes autism,” stated Dr. Nathaniel DeNicola, who provides counsel to the American College of Obstetricians and Gynecologists on environmental matters. He further described the studies exploring this connection as “too deeply and fundamentally flawed to draw reliable conclusions.”
The authors of the very latest report themselves acknowledged that their findings do not establish a direct cause-and-effect relationship. “We cannot answer the question about causation — that is very important to clarify,” explained Dr. Diddier Prada, an epidemiologist at Mt. Sinai and one of the study’s authors, in an interview this month.
Due to ethical considerations, direct pharmaceutical research on pregnant women is not feasible. Consequently, all existing studies on acetaminophen’s effects are observational, relying on researchers to analyze pregnancy data and track children’s development over time. This approach makes it challenging to account for all the variables that might differentiate women who use Tylenol during pregnancy from those who do not.
Dr. Brian Lee, a professor of epidemiology at Drexel University, noted that many studies in the new review “did not necessarily go to the greatest lengths to account for possible confounders,” referring to other influencing factors. He highlighted that “the biggest elephant in the room here is genetic confounding, because we know autism, ADHD and other neurodevelopmental disorders are highly heritable.”
In 2024, Dr. Lee co-authored a significant study that examined the health records of 2.5 million children in Sweden. Although an initial analysis showed a small positive association between maternal acetaminophen use and the incidence of autism, ADHD, and intellectual disability, this link vanished after a subsequent sibling comparison, where children born to the same mothers were analyzed. The sibling study’s results suggested that “maternal genetics,” rather than acetaminophen, might be the true underlying cause, according to Dr. Lee.
Currently, pregnant women are already encouraged to take folic acid — of which leucovorin (the form expected to be recommended in the Health Department’s report) is a variant — early in pregnancy to support healthy fetal brain development. Some research also indicates that folic acid supplementation might improve behavioral outcomes, including communication skills, in children with autism, though these findings are still preliminary.