Tylenol Autism and ADHD Lawsuits Reinstated by Federal Appeals Court

Ruling determined the MDL judge wrongly excluded plaintiffs’ expert witnesses from testifying at trial about the link between Tylenol and autism, ADHD and other developmental injuries.

More than 500 Tylenol autism and ADHD lawsuits will be reinstated after a federal appeals court overturned a prior decision that excluded key plaintiffs’ experts from presenting evidence about risks associated with the use of acetaminophen during pregnancy, which essentially brought the federal litigation to an end more than two years ago.

The litigation involves allegations that children developed autism or attention deficit hyperactivity disorder (ADHD) after their mothers used Tylenol or generic acetaminophen during pregnancy.

In October 2022, the federal claims were consolidated as part of a multidistrict litigation in the Southern District of New York, where U.S. District Judge Denise Cote was appointed to oversee coordinated discovery and pretrial proceedings. However, in August 2024 Judge Cote dismissed the litigation and excluded key expert testimony plaintiffs intended to use to establish that prenatal acetaminophen exposure can cause the developmental disorders.

Now, the U.S. Court of Appeals for the Second Circuit has ruled that three of those experts should not have been excluded, sending the cases back to Judge Cote for further proceedings. While the decision does not establish that Tylenol causes autism or ADHD, it allows plaintiffs to continue pursuing their claims and present their supporting scientific evidence.

Tylenol Autism and ADHD Claims

The popular painkiller and anti-inflammatory drug Tylenol (acetaminophen) has been widely used by pregnant women for decades and was long considered to be safe for unborn children. However, recent years have seen several studies reporting associations between prenatal acetaminophen use and an increased risk of developmental disorders like autism and attention deficit hyperactivity disorder.

Potential links between Tylenol pregnancy use, autism and ADHD have been hotly debated, with some studies supporting the link and others not. In September, the U.S. Food and Drug Association (FDA) stepped in, adding new Tylenol label warnings calling for pregnant women to use the drug with caution and only when necessary.

Tylenol Autism and ADHD Lawsuits Reinstated

Following coordinated discovery and pretrial proceedings in the MDL, Judge Cote excluded all plaintiffs’ expert witnesses from testifying nearly two years ago, determining that the scientific methods used by those witnesses were not reliable enough to link Tylenol pregnancy use with ADHD and autism. With no way remaining to prove causation, the entire MDL was dismissed before any trials took place.

Plaintiffs subsequently appealed that decision to the U.S. District Court of Appeals for the Second Circuit, which released its opinion (PDF) on July 13, reversing Judge Cote’s decision, reinstating the dismissed cases and sending the litigation back to the Southern District of New York for reconsideration.

According to the decision, Judge Cote overstepped her bounds in dismissing the cases, saying three of the five plaintiffs’ expert witnesses should be allowed to testify and be given the opportunity to convince a jury of the potential connection between the drug and developmental disorders. In fact, the data of one of the dismissed expert witnesses was referenced by the FDA in requiring the latest Tylenol label warnings.

“Those concededly qualified experts offered opinions that comport with methodologies applied by other scientists in their fields, and constitute acceptable interpretations of scientific evidence where scientists may, and in fact do, disagree on the ultimate answer to the causal question that they are assessing.”

– U.S. Senior Circuit Judge Guido Calabresi, writing for the majority

The ruling does not establish that Tylenol causes ADHD or autism but instead indicates that plaintiffs presented expert witnesses who should have been allowed to proceed with their testimony. The appeals court indicated its ruling was completely based on the admissibility of evidence.

Kenvue, the Johnson & Johnson spinoff that now owns Tylenol, issued a statement on Monday addressing the appellate court ruling, saying they intend to show the court again that the expert witnesses’ testimony would be unreliable. The statement indicates Kenvue is “exploring all options regarding this decision.”

The litigation will now be returned to Judge Cote for further reconsideration, which could result in the reinstatement of a plan to hold a series of bellwether trials for the Tylenol autism lawsuits. These would allow lawyers from both sides to see exactly how juries weigh those expert witnesses testimony and other key evidence that would likely play out in the majority of claims.

Although the outcomes of those trials would not be binding on other cases, Tylenol autism attorneys and defendants will closely watch the results, which could present an avenue for a global settlement agreement.

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