Study Finds No Evidence Linking Tylenol to Increased Risk of ADHD, Autism for Unborn Children

Once researchers looked at sibling matches, they determined that confounding familial factors may have influenced previous studies that linked prenatal exposure to Tylenol to autism and ADHD.

The findings of a new study suggest Tylenol use during pregnancy is not linked to an increased risk of autism or attention deficit hyperactivity disorder (ADHD) among children exposed to the popular pain reliever in utero, despite previous research to the contrary.

In a report published earlier this month in the Journal of the American Medical Association (JAMA), researchers from Sweden indicate that previous studies may have mistakenly linked Tylenol to ADHD and autism due to confounding factors that were not linked to a causal connection.

For decades, Tylenol (acetaminophen) has been widely used by pregnant women, largely due to the widespread belief that it is safe for unborn children. However, a growing number of lawsuits have been filed in state and federal courts in recent years, each raising similar allegations that drug makers failed to adequately warn pregnant women and the medical community about the growing evidence that prenatal exposure toTylenol causes autism or ADHD.

In this latest study, researchers from the Karolinska Institutet in Stockholm conducted a population-based study using data from nearly 2.5 million children born in Sweden from 1995 to 2019, with follow-ups through December 31, 2021.

According to the findings, 185,909 children were exposed to acetaminophen during pregnancy. Researchers found that 1.53% were diagnosed with autism, compared to 1.33% among those who were not exposed. ADHD rates were 2.87% for those exposed to acetaminophen, compared to 2.46% who were not.

In order to address possible confounding factors, researchers looked at sibling control matches, and found no evidence acetaminophen use was linked to an increased autism, ADHD or any intellectual disability risk once confounding factors were accounted for.

“Acetaminophen use during pregnancy was not associated with children’s risk of autism, ADHD, or intellectual disability in sibling control analysis,” the researchers concluded. “This suggests that associations observed in other models may have been attributable to familial confounding.”

April 2024 Tylenol Autism and ADHD Lawsuit Update

The findings of this new study come several months after the U.S. District Judge presiding over all federal Tylenol autism and ADHD lawsuits dismissed the litigation, after rejecting the plaintiffs’ expert testimony that claimed prenatal exposure to acetaminophen caused individual children’s injuries. However, the court recently agreed to consider new expert evidence in Tylenol lawsuits that were filed after the initial order.

Given common questions of fact and law over the adequacy of the Tylenol pregnancy warnings, the U.S. Judicial Panel on Multidistrict Litigation (JPML) established coordinated pretrial proceedings last year, centralizing all claims brought throughout the federal court system before U.S. District Judge Denise Cote in the Southern District of New York, as part of a federal multidistrict litigation (MDL).

In December, Judge Cote issued an opinion excluding plaintiffs’ expert witnesses from testifying about the Tylenol pregnancy side effects, after determining the scientific approaches and studies used were not sound enough to allow the opinions to be presented to a jury.

The move has been seen as spelling the end of the Tylenol litigation in the federal court system, since it left plaintiffs without required expert testimony to prove Tylenol caused developmental disorders when women took the painkiller during pregnancy.

After the decision, plaintiffs were given time to show cause why no summary judgment should be issued dismissing their cases, but about 500 of the cases were dismissed in February. However, the ruling does not apply to Tylenol ADHD and autism lawsuits being pursued in state courts nationwide, and families who have filed complaints since the ruling have argued they should be allowed to present new evidence.

How the findings of this latest study will impact the litigation is yet to be known.