Federal Appeals Court Upholds Tylenol Pregnancy Lawsuits Linking Use to Autism and ADHD Diagnoses

A U.S. appeals court has reversed a lower court’s dismissal of lawsuits against Tylenol manufacturers, allowing hundreds of cases where families allege their children’s autism or ADHD diagnoses were caused by prenatal Tylenol exposure.

The panel, composed of Democratic appointees, ruled the trial judge erroneously excluded scientific evidence presented by plaintiffs’ experts, emphasizing that such testimony addresses an ongoing scientific debate.

This decision follows recommendations from former President Trump and health advisers warning about potential risks, though scientific consensus remains unresolved. While preliminary studies suggest a slight association, large-scale trials controlling for genetics and lifestyle factors have found no causal link.

Major medical organizations, including the American College of Obstetricians and Gynecologists, continue to classify Tylenol as the safest pain relief option during pregnancy, noting that untreated maternal fever poses risks to fetal development.

The court acknowledged the national debate but stressed their ruling focuses solely on evidence admissibility, not causation. “We are not deciding whether there is a general causal relationship between acetaminophen and neurodevelopmental disorders,” the judges clarified.

The case hinges on the credibility of plaintiffs’ expert witness Andrea Baccarelli, Harvard T.H. Chan School of Public Health dean, whose 2025 report claimed frequent high-dose acetaminophen use during pregnancy showed “substantial evidence” of a causal link. District Judge Denise Cote previously dismissed his testimony as cherry-picked data.

During oral arguments, Judge Gerard Lynch supported admitting the evidence, stating “reasonable scientists do appear to disagree” on the issue. Plaintiffs’ attorney Ashley Keller hailed the ruling as validation of their clients’ claims.

Tylenol’s manufacturer Kenvue, spun off from Johnson & Johnson in 2023, and retail chains selling generic versions maintain no proven link exists. “Credible, independent science shows no connection between acetaminophen and autism or ADHD,” asserted spokesperson Melissa Witt, adding the company will continue defending its product.

Researchers have studied acetaminophen’s fetal brain effects for over a decade, but conclusive data is lacking due to ethical constraints preventing controlled trials. Observational studies face challenges isolating acetaminophen’s impact from genetic and environmental factors.

Baccarelli’s August 2025 analysis of 46 studies found an association, a conclusion cited in Trump administration prenatal warnings. However, critics point to a January 2025 Lancet review prioritizing studies accounting for genetic factors—comparing siblings born to the same mother—which found no link. A June 2025 Hong Kong sibling-controlled study of 700,000 cases reached similar conclusions.

The court emphasized their decision does not endorse causality, stating they are only ruling on the appropriate judicial scrutiny of expert testimony methodologies. “We are called upon to decide how closely a trial court may scrutinize a qualified expert’s conclusions when that expert follows generally accepted methodologies,” the judges wrote.

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