A federal appeals court is weighing whether to reinstate more than 500 lawsuits that claim prenatal exposure to Tylenol and acetaminophen caused autism or attention-deficit/hyperactivity disorder.
A district judge dismissed the cases in 2023 after ruling that the plaintiffs' experts did not present reliable scientific evidence, as reported by ABC News.
The judge wrote that the experts used an approach that allowed selective use of data and did not address inconsistencies in the research record.
Two members of a three-judge panel on the U.S. Court of Appeals for the 2nd Circuit questioned whether the dismissal was premature.
Circuit Judge Gerard Lynch said during arguments that he was not convinced the testimony should have been excluded.
Circuit Judge Guido Calabresi suggested that the cases might have been appropriate for a jury to weigh.
The issue drew national attention after the Trump administration announced in September that prenatal use of acetaminophen may be linked to an increased risk of autism and urged limited use during pregnancy.
Federal officials pointed to a 2025 meta-analysis involving researchers from several universities that reported an association between prenatal exposure and later neurodevelopmental disorders.
Other studies have reached different conclusions.
A study funded by the National Institutes of Health published in 2024 found no link between acetaminophen use during pregnancy and autism, ADHD or intellectual disability.
A review in the British Medical Journal this year also reported no clear evidence of a connection.
The legal landscape widened last month when Texas Attorney General Ken Paxton sued Tylenol manufacturers Johnson & Johnson and Kenvue, alleging deceptive marketing of the medication to pregnant women.
Kenvue has rejected claims that its products are linked to autism.
The company said research shows acetaminophen does not cause autism and warned that limiting access could leave pregnant women with unsafe options.
Health and Human Services Secretary Robert F. Kennedy Jr. has made acetaminophen use in pregnancy a priority within his autism agenda.
He directed the FDA to issue a physician notice warning about possible risks linked to prenatal exposure.
Kennedy ordered the FDA to begin adding new pregnancy safety language to acetaminophen labeling while launching an HHS initiative to study neurodevelopmental outcomes in children exposed in utero.
He paired those steps with broader autism research projects at NIH focused on environmental and medical exposures.
Jim Mishler ✉
Jim Mishler, a seasoned reporter, anchor and news director, has decades of experience covering crime, politics and environmental issues.
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