A federal appeals court is reviewing over 500 lawsuits filed by parents who allege that prenatal exposure to Tylenol caused their children's autism or attention deficit hyperactivity disorder (ADHD). These lawsuits were dismissed in December 2023 by U.S. District Judge Denise Cote, who determined that the scientific evidence presented by the plaintiffs' experts was not credible. In her ruling, Cote stated that the experts' methods allowed for selective data interpretation, which obscured the complexities and weaknesses in the evidence.

During a recent hearing, two judges from a three-judge panel on the U.S. Court of Appeals for the Second Circuit expressed skepticism about the dismissal. Circuit Judge Gerard Lynch questioned the district court's conclusion, stating, "I'm having trouble understanding why the district court was correct to say that this just is nonsense. This is something that no one should hear." He emphasized the importance of having reputable scientists explain their methodologies.

Circuit Judge Guido Calabresi also suggested that the cases might have warranted a jury trial. He noted, "It seems to me you're constantly coming back to where you began, which is [the experts] didn't show that there was a causal link, but a causal link cannot be shown." He highlighted that the presence of evidence is crucial for juries or courts to make determinations.

The issue gained attention after the Trump administration's announcement in September that Tylenol use during pregnancy might be linked to an increased risk of autism, urging pregnant women to limit its use. However, studies have not established a direct cause-and-effect relationship. While some research indicates a potential link, major medical organizations, including the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists, continue to recommend acetaminophen as the safest pain reliever during pregnancy, advising consultation with healthcare providers.

Federal officials referenced a meta-analysis from August 2025, which suggested a possible association between prenatal acetaminophen exposure and neurodevelopmental disorders. Conversely, an April 2024 study funded by the National Institutes of Health found no link between acetaminophen use during pregnancy and increased risks of autism, ADHD, or intellectual disabilities. A recent review published in the BMJ also found no clear evidence connecting acetaminophen use in pregnancy to autism or ADHD.

In a related development, Texas Attorney General Ken Paxton filed a lawsuit against Tylenol manufacturers Johnson & Johnson and Kenvue, alleging deceptive marketing practices regarding the medication's safety for pregnant women. Johnson & Johnson has marketed Tylenol for decades, while Kenvue, a spinoff of its consumer health division, has been selling the drug since 2023. Kimberly Clark, a multinational consumer goods corporation, recently announced plans to acquire Kenvue.

Kenvue has defended its products against claims linking them to autism. In a statement, the company asserted that research supports the safety of acetaminophen for pregnant women. "We strongly disagree with any suggestion otherwise and are deeply concerned with the health risk this poses for expecting mothers," the statement read. "Acetaminophen is the safest pain reliever option for pregnant women as needed throughout their entire pregnancy. Without it, women face dangerous choices: suffer through conditions like fever that are potentially harmful to both mom and baby or use riskier alternatives."