A U.S. federal appeals court has revived more than 500 lawsuits against Tylenol maker Kenvue, allowing expert testimony linking prenatal acetaminophen exposure to autism and ADHD to be considered in court.
A federal appeals court in the United States has reinstated more than 500 product liability lawsuits against Kenvue, the manufacturer of Tylenol, over claims that using the pain reliever during pregnancy may be associated with autism and attention deficit hyperactivity disorder (ADHD) in children.
The United States Court of Appeals for the Second Circuit ruled that a lower court had improperly excluded testimony from three medical experts presented by parents and guardians pursuing the claims.
Appeals Court Reopens the Cases
In a 64-page opinion, Circuit Judge Guido Calabresi said the experts relied on scientific methods accepted within the research community. He noted that differing interpretations of scientific evidence do not automatically make expert testimony inadmissible.
However, the court emphasized that it did not conclude that acetaminophen, the active ingredient in Tylenol, causes autism or ADHD. Instead, the ruling only addressed whether the expert opinions should be heard during legal proceedings.
The lawsuits will now return to the district court for further proceedings.
Kenvue Maintains Tylenol Is Safe
Kenvue said the decision does not alter the existing scientific consensus regarding Tylenol’s safety.
In a statement, the company said credible and independent scientific evidence has not established a proven causal link between acetaminophen use during pregnancy and autism or ADHD. Kenvue added that it intends to continue challenging the reliability of the plaintiffs’ expert testimony during the next phase of litigation.
Medical organizations continue to recommend acetaminophen as the preferred medication for treating pain and fever during pregnancy when used as directed.
Major Retailers Also Named
In addition to Kenvue, several major U.S. retailers have been named as defendants in the lawsuits, including CVS Health, Kroger, Target, Walgreens, and Walmart.
Tylenol was manufactured for more than six decades by Johnson & Johnson, which spun off Kenvue as a separate consumer health company in 2023. Johnson & Johnson has also consistently defended the safety profile of the medication.
Kenvue is currently in the process of being acquired by Kimberly-Clark in a deal valued at more than $40 billion, with the transaction expected to close later this year.
Expert Testimony Reinstated
The appeals court ruled that testimony from several experts—including Andrea Baccarelli, psychiatrist Eric Hollander, and toxicologist Brandon Pearson—should not have been excluded.
Lawyers representing the plaintiffs welcomed the decision, saying the court unanimously recognized that their experts had applied accepted scientific methods in reaching their conclusions.
The lawsuits had previously been dismissed in December 2024 by a federal district court, which questioned the reliability of the expert evidence. Monday’s ruling allows those cases to move forward once again.
