Judge Refuses to Hear Expert Testimony on Tylenol Link to Autism, ADHD


The 440 lawsuits brought against Tylenol and generic acetaminophen manufacturers do not have “admissible evidence” to show that prenatal exposure to the medication can lead to autism spectrum disorder or attention-deficit/hyperactivity disorder, a federal judge ruled this week.

Judge Refuses to Hear Expert Testimony on Tylenol Link to Autism, ADHD  acetaminophen

The 440 lawsuits brought against Tylenol and generic acetaminophen manufacturers do not have “admissible evidence” to show that prenatal exposure to the medication can lead to autism spectrum disorder (ASD) or attention-deficit/hyperactivity disorder (ADHD), a federal judge ruled this week.

The news comes as a blow to the hundreds of families who filed lawsuits alleging their child developed ASD and/or ADHD as a result of the mother taking acetaminophen during the pregnancy.

U.S. District Judge Denise Cote in the Southern District of New York, who is presiding over the cases, in her 148-page opinion wrote that, in the absence of admissible evidence, the District Court will not hear the plaintiff’s expert testimony.

The ruling “effectively kills” the consolidation of lawsuits, Bloomberg reported. The Defender asked lawyers with four of the main firms handling the cases for comment, but they did not respond by our publication deadline.

The lawsuits allege retailers, including Walmart, CVS, Walgreens and others, falsely advertised products that contain acetaminophen as being safe for pregnant women and did not warn them about the risks posed to fetal development.

Johnson & Johnson’s former consumer health unit, now a separate company called Kenvue, told Reuters in a statement it will move to dismiss the lawsuits in light of the ruling. Johnson & Johnson, the original maker of the Tylenol brand, was not named in the suits.

Since the mounting number of cases shared common questions of fact and law regarding the adequacy of the Tylenol pregnancy warnings, the U.S. Judicial Panel on Multidistrict Litigation (JPML) in late 2022 centralized all the lawsuits brought throughout the federal court system into federal multidistrict litigation (MDL) brought before Judge Cote.

Commenting on the court’s latest decision, Brian Hooker, Ph.D.Children’s Health Defense senior director of science and research, told The Defender:

“The judge has ignored a mountain of evidence in order to genuflect to Johnson & Johnson by denying the plaintiff’s expert testimony to move forward. This essentially denies justice to the many families with ASD children and is a slap in the face to the developmental disability community in general.”

Meanwhile, William Parker, Ph.D. — who for the last 10 years has researched acetaminophen risks — said the judge’s ruling was “great” because “it gets us one step closer to figuring out when the drug causes neurological disorders like ASD so we can 1) stop widespread acetaminophen use in the population most at-risk, and 2) hold those responsible accountable.”

Pregnancy lawsuits could be a ‘red herring’

Parker said that it is a “scientific fact” that many autism cases are induced by acetaminophen — but that this mostly happens once the baby is born, not while in utero. He told The Defender:

“It would be horrible if this lawsuit moved forward because it could convince everyone that the induction of autism mostly happens during pregnancy. This could be a massive red herring, and could result in continued use of the drug in the pediatric — especially neonatal — population, which would be catastrophic.”

Parker is a visiting scholar in the psychology and neuroscience department at the University of North Carolina, Chapel Hill, and the CEO of WPLab, a nonprofit that focuses on research and education about acetaminophen’s impact on the developing brain.

He previously was a researcher at Duke University for 27 years and has authored more than 140 peer-reviewed articles.

Newborns, young kids most at risk

Based on Parker’s read of the science on acetaminophen and health risks, he said a fetus is “pretty safe” during pregnancy compared to when the umbilical cord is cut.

“When you cut the umbilical cord, everything changes because you no longer have the mother’s liver there to protect the fetus. The bottom line is that babies — especially freshly born babies, neonates, we call them — are not wired to process pharmaceuticals.”

Parker said the judge’s ruling did not surprise him because the lawsuits are narrowly focused on examining the scientific evidence of prenatal exposure to acetaminophen.

“I think that overall what I would have expected was exactly what that judge decided because, if you read her commentary, there’s no peer-reviewed publication that says this is happening during pregnancy.”

However, if the lawsuits had been about exposure to acetaminophen after birth, particularly shortly after birth, they would have had a firmer foundation of peer-reviewed studies on which to base their claims, he said.

For example, a 2022 peer-reviewed study proved that acetaminophen use in infants and children was never shown to be safe for neurodevelopment.

In June, Parker and colleagues published in the peer-reviewed journal Clinical and Experimental Pediatrics a review of studies on acetaminophen and neurodevelopmental injury in young kids, in which they concluded that “there is no valid rationale for controversy regarding the conclusion that early life exposure to acetaminophen causes neurodevelopmental injury in susceptible babies and small children.”

Parker said the literature regarding a causal link between acetaminophen exposure and ASD is “clear” while the research on the causal link between the drug and ADHD is “more complex.” He has focused his efforts on exposing how the drug causes ASD.

When used by adults, the drug is fairly safe under certain circumstances, Parker said. “For example, more than 50 million adult Americans use it every week, and, as a result, you get about two accidental deaths during the same time period.”

“That’s a very safe drug by most measures, but of course that applies only in adults,” he added.

Plaintiffs: Tylenol should carry a warning

Before rendering her decision, Judge Cote earlier this year asked the plaintiffs’ lawyers to propose an example of the acetaminophen pregnancy warnings that should have been provided to expecting mothers.

Products that contain the drug include Tylenol, Alka-Seltzer Plus, DayQuil, Excedrin, Goody’s, Mucinex, NyQuil, Robitussin and some generic and store-brand equivalents.

In April, the lawyers sent a letter that included some of the existing language used on warning labels in Europe:

Autism/ADHD: Some studies show that frequent use of this product during pregnancy may increase your child’s risk of autism and attention deficit hyperactivity disorder. If you use this product during pregnancy to treat your pain and/or fever, use the lowest effective dose for the shortest possible time and at the lowest possible frequency.”

The lawyers said the defendants could have used this or different language to warn pregnant women about Tylenol autism risks.

Judge cites FDA review

Cote in April invited the U.S. government — particularly FDA regulators — to weigh in and then made a decision that aligned with the FDA’s view. She wrote in her opinion:

“Because this MDL raises important issues related to public health and drug safety for pregnant women and their offspring, the Court invited the United States, including the Food and Drug Administration (‘FDA’), to submit its views on the Plaintiffs’ Proposed Warning.”

Cote asked the FDA to weigh in on two questions by July 28, or as soon thereafter as possible:

  1. Should the Plaintiffs’ Proposed Warning be added to acetaminophen labels?
  2. As of today, does science warrant the addition to acetaminophen labels of any warning or advice regarding in utero exposure to acetaminophen and the risk of ASD or ADHD?

The FDA on July 28 sent a response letter, via Damian Williams, the U.S. Attorney for the Southern District of New York, saying the agency needed more time to put together its response. The same day, Cote extended the deadline to Sept. 15.

A week before the deadline, the U.S. Department of Justice wrote to Cote, saying it had consulted with the FDA and the agency would not share its opinion on a potential risk label for Tylenol products.

The letter did, however, include the FDA’s most recent review of pertinent studies. In her opinion, Cote wrote:

“The Government declined to submit a Statement of Interest but noted in its letter the FDA’s independent 2023 conclusion (discussed in more detail infra [Latin for ‘below’]) that the scientific evidence on this topic is as of yet ‘unable to support a determination of causality.’”

Cote went on to cite the FDA’s research and regulatory activities since 2014 on prenatal acetaminophen exposure and discuss the FDA’s review of the three most recent studies on acetaminophen exposure in utero.

She cited the FDA’s conclusion:

“Overall, findings on the associations between APAP [acetaminophen] use during pregnancy and neurobehavioral and urogenital outcomes remain mixed.

“The three studies reviewed here are limited and do not change DEPI-I’s [the FDA’s Division of Epidemiology I] conclusions from its most recent review — the limitations and inconsistent findings of current observational studies of APAP and neurobehavioral and urogenital outcomes are unable to support a determination of causality.”

Cote concluded, “As the FDA’s reviews of these studies have recorded time and again, the literature remains mixed.”

It appears to have been beyond the scope of Cote’s consideration if and to what extent industry influences may have interfered with the FDA’s review.