A lawsuit against the manufacturers of Tylenol arguing its alleged link to autism can proceed after a U.S. appeals court reversed the decision of a judge who previously dismissed it over a lack of scientific evidence.
The move has revived more than 500 private lawsuits against Tylenol maker Kenvue and comes less than a year after President Donald Trump urged pregnant women not to take the painkiller over its links to autism — a claim scientists said is based on “no evidence whatsoever.”
Appeals judges, all Democratic appointees, ruled Monday that the lower court was wrong to exclude expert testimony from three doctors offered by parents and guardians who tied Tylenol use during pregnancy to autism and ADHD in children.
The private lawsuits were dismissed in December 2024 by U.S. District Judge Denise Cote in Manhattan, who criticized the methodology of the plaintiffs’ expert witnesses.
One of the expert witnesses included Andrea Baccarelli, the dean of Harvard University’s School of Public Health. Baccarelli submitted a report that said “when children are exposed to acetaminophen—also known by the brand name Tylenol or as paracetamol—during pregnancy, they may be more likely to develop neurodevelopmental disorders.”
The link remains unproven, and Baccarelli said in a previous statement that “further research is needed to confirm the association and determine causality.” Still, the expert’s evidence was wrongly excluded from the lawsuit previously, the appeals judges ruled.
Baccarelli also consulted with Trump’s health officials, including Health Secretary Robert F. Kennedy Jr, ahead of the president’s announcement in September 2025, where he warned of the so-called link between Tylenol and autism.
“Baccarelli said he had discussed his study with Health and Human Services Secretary Robert F. Kennedy Jr. in the weeks leading up to that announcement and provided the White House team with a statement noting his research found “evidence of an association” between prenatal exposure to acetaminophen and neurodevelopmental disorders,” Harvard School of Public Health said in a statement last year.
In reversing the lower court’s decision, Circuit Judge Guido Calabresi stressed that the appeals court was not deciding whether using acetaminophen causes autism or ADHD, or whether elected officials should do more to protect public health.
However, judges acknowledged the “backdrop of significant debate in the relevant scientific communities” and that the debate has also become political. “But the issue before us is not political,” they wrote in the 64-page decision.
“We are pleased that the panel unanimously found that our key experts reliably applied their scientific methods and principles,” Ashley Keller, a lawyer for the parent plaintiffs said in a statement.
Kenvue maintained that Tylenol is safe in a statement Monday, and said the decision “does not change the fact that credible, independent science shows no proven link between taking acetaminophen and autism or attention deficit hyperactivity disorder.”
The company plans to again try to show in court that the opinions of the plaintiffs’ experts are unreliable.
Reuters contributed to this report
