Tylenol Makers Seek Rehearing for Acetaminophen Autism Lawsuits by Appeals Court

As additional Tylenol autism and ADHD claims continue to be investigated, drug manufacturers are challenging a court ruling that revived hundreds of lawsuits.

Kenvue, which used to be Johnson & Johnson’s consumer pharmaceutical division, is asking a federal appeals court to reconsider the reinstatement of hundreds of Tylenol autism and ADHD lawsuits alleging that use of the common painkiller, acetaminophen, during pregnancy increases the risk of developmental disorders in offspring.

Families pursuing the claims allege Johnson & Johnson, Kenvue and retailers that sold acetaminophen products failed to adequately warn pregnant women that prenatal exposure may increase the risk of autism and attention deficit hyperactivity disorder (ADHD). The manufacturers deny that acetaminophen causes the developmental disorders.

Tylenol Autism and ADHD Concerns

Tylenol contains acetaminophen, one of the most commonly used pain relievers and fever reducers during pregnancy. For decades, the medication was widely considered an appropriate option for pregnant women when used as directed.

However, a number of studies in recent years have reported associations between prenatal acetaminophen exposure and an increased risk of autism, ADHD and other developmental problems in children. Researchers continue to debate whether acetaminophen itself causes those outcomes or whether other factors may explain the associations seen in some studies.

Those scientific questions have become a central issue in the litigation, with plaintiffs maintaining that the available research was strong enough to warrant warnings for pregnant women, while manufacturers argue the evidence does not establish a causal relationship.

In September 2025, the U.S. Food and Drug Administration (FDA) added new Tylenol label warnings advising pregnant women to use acetaminophen cautiously, and only when medically necessary.

Acetaminophen Autism Lawsuits

Federal Tylenol autism and ADHD lawsuits were centralized in the Southern District of New York in October 2022, where U.S. District Judge Denise Cote was assigned to oversee coordinated discovery and pretrial proceedings.

In 2024, Judge Cote dismissed the litigation after excluding key expert testimony offered by plaintiffs to support claims that acetaminophen use during pregnancy can cause autism and ADHD in children. Without that testimony, the plaintiffs were unable to establish the scientific causation needed to move the cases toward trial.

Plaintiffs appealed, and in July 2026, the U.S. Court of Appeals for the Second Circuit overturned that decision, reinstating the Tylenol autism and ADHD lawsuits and returning the litigation to Judge Cote for further proceedings.

The defendants are now asking the appeals court to revisit that ruling. On September 10, they filed a petition for rehearing (PDF), arguing that the appeals court gave too little deference to Judge Cote’s role in deciding whether expert testimony is scientifically reliable enough to be presented to a jury.

Kenvue and the other defendants have also asked the court to clarify that its July ruling does not automatically make the plaintiffs’ experts admissible. Instead, they argue Judge Cote should still be allowed to reconsider whether some or all of that testimony meets the legal standards required for trial.

If the Second Circuit leaves its ruling in place, the cases will return to Judge Cote and could move toward a series of bellwether trials. Those early trials would allow both sides to see how juries respond to the expert testimony and other evidence expected to be central to many of the lawsuits.

Bellwether results would not determine the outcome of other Tylenol autism and ADHD claims, but they could help the parties evaluate the litigation and explore a potential settlement. If no broader resolution is reached, individual lawsuits may eventually be returned to their original federal courts for separate trial dates.

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