Tylenol maker Kenvue is asking a U.S. appeals court to reconsider its decision to revive more than 500 lawsuits alleging that the painkiller may be linked to autism and ADHD.
Kenvue joined major retailers and pharmacy operators in filing the request with the 2nd U.S. Circuit Court of Appeals in Manhattan. The companies want the court to revisit its July 13 ruling that allowed the lawsuits to move forward.
The defendants argue that a federal district judge properly excluded expert testimony supporting the plaintiffs’ claims. They say the appeals court should have deferred to that decision.
Kenvue Challenges Expert Evidence
The legal dispute centers on three experts whose testimony U.S. District Judge Denise Cote previously excluded.
They include Andrea Baccarelli, dean of the Harvard T.H. Chan School of Public Health; Eric Hollander, a psychiatry professor at Albert Einstein College of Medicine; and Brandon Pearson, a toxicologist who previously worked at Columbia University.
The experts offered opinions linking acetaminophen use during pregnancy with autism and ADHD in children.
However, the defendants argue that their opinions do not meet the legal standard for reliable scientific evidence.
They also say federal evidence rules give trial judges an important role in deciding whether expert testimony can reach a jury.
Companies Say Juries Should Not Decide Scientific Questions
In their filing, the defendants argued that jurors should not have to resolve highly complex and unsettled scientific questions without reliable expert evidence.
The companies said the appeals court gave too little weight to the district judge’s role as a gatekeeper for scientific testimony.
If the appeals court refuses to reverse its July decision, the defendants want it to clarify that the experts’ opinions are not automatically admissible.
They are also asking the court to send the issue back to Judge Cote for another review.
Appeals courts rarely reconsider their own decisions. Therefore, the companies face a difficult legal challenge.
More Than 500 Lawsuits Remain at Issue
The plaintiffs include parents and guardians who claim their children suffered autism or ADHD after prenatal exposure to Tylenol or generic acetaminophen.
The defendants include Kenvue as well as Albertsons, Costco, CVS, Dollar General, Dollar Tree, Family Dollar, Kroger, Safeway, 7-Eleven, Target, Walgreens and Walmart.
The companies argue that the scientific evidence does not establish that acetaminophen causes autism or ADHD.
Earlier litigation had produced a major victory for the defendants. In 2024, Judge Cote ruled that the plaintiffs could not proceed without the expert testimony. The Second Circuit later revived the cases after finding that the lower court had gone too far in excluding the evidence.
What Science Says About Tylenol and Autism
The legal battle has attracted intense public attention because of claims about acetaminophen use during pregnancy.
Some studies have reported associations between prenatal acetaminophen exposure and neurodevelopmental conditions. However, an association does not prove that the medicine causes autism or ADHD.
Large studies have also failed to establish a causal relationship. Major medical organizations continue to regard acetaminophen as an important option for treating pain and fever during pregnancy.
Kenvue has defended the medicine’s safety and has rejected claims that acetaminophen causes autism.
Appeals Court Faces Rare Reconsideration Request
The latest filing puts the Second Circuit in an unusual position.
The court must now decide whether to reconsider its own July ruling or allow the revived lawsuits to continue.
For Kenvue and the other defendants, the expert evidence remains central to the case. For the families suing the companies, the appellate ruling reopened a path toward having their claims heard in court.
The dispute therefore remains focused on a fundamental question: should the scientific evidence be decided by judges before trial, or should juries ultimately weigh the competing claims?
For now, the Second Circuit has not indicated whether it will reconsider its decision.
