Ken Paxton, the Republican attorney general of Texas, sued the makers of Tylenol on Tuesday, claiming that the companies hid the risks of the drug on brain development in children.

The lawsuit is the latest fallout from President Donald Trump’s claim last month that use of Tylenol during pregnancy can cause autism. That link is unproven.

Paxton filed the suit against Johnson & Johnson, which sold Tylenol for decades, and Kenvue, a spinoff company that has sold the drug since 2023.

The Texas lawsuit claims that the companies knowingly withheld evidence from consumers about Tylenol’s links to autism and attention deficit hyperactivity disorder. The suit also claims that Kenvue was created to shield Johnson & Johnson from liability over Tylenol.

This lawsuit is the first by a state that seizes on Trump’s allegations that the use of acetaminophen products like Tylenol during pregnancy could cause neurodevelopmental disorders. The issue has been a long-standing concern among some followers of Robert F. Kennedy Jr., the nation’s top health official, but the idea gained traction with Trump’s remarks.

Kenvue has repeatedly defended Tylenol’s safety and rejected Trump’s claims about the drug’s use during pregnancy and autism.

“We will defend ourselves against these baseless claims and will respond per the legal process,” Melissa Witt, a spokesperson for Kenvue, said on Tuesday. “We stand firmly with the global medical community that acknowledges the safety of acetaminophen and believe we will continue to be successful in litigation as these claims lack legal merit and scientific support.”

In other litigation, Johnson & Johnson has said that it had always acted responsibly in warning consumers about Tylenol’s proven risk of liver damage when taken in excess.

Clare Boyle, a spokesperson for Johnson & Johnson, said Tuesday that the company “divested its consumer health business years ago, and all rights and liabilities associated with the sale of its over-the-counter products, including Tylenol (acetaminophen), are owned by Kenvue.”

Hundreds of lawsuits in state and federal courts have been filed in recent years by families who claimed that their children were diagnosed with autism or ADHD after use of Tylenol during pregnancy.

In the largest group of cases, filed in federal court, a U.S. judge in New York dismissed the lawsuits, citing a lack of reliable scientific evidence. The plaintiffs are appealing the decision, with a hearing in front of an appellate panel scheduled for Nov. 17.

For years, scientists have conducted research on a potential connection between acetaminophen and neurodevelopmental disorders, but the studies have so far produced mixed results.

Medical groups pushed back against the Trump administration’s warning in September, saying Tylenol was the only pain reliever safe for use during pregnancy to treat high fevers. If untreated, they pose serious risks to the health of the baby and the mother.

Paxton, who is challenging Sen. John Cornyn, the incumbent, in the Republican primary next year, has been aggressive in filing litigation that aligns with Trump’s priorities. He has challenged the results of the 2020 election, sued nonprofits representing immigrants’ rights and sought to remove Democratic lawmakers from office in Texas during a battle over redistricting. Though not always successful, Paxton’s legal efforts have generated deep support for him among Texas Republicans.

Last month, the Food and Drug Administration said it was seeking to include a warning on the drug’s label about the connection to neurodevelopmental disorders. Kenvue said it would oppose the changes, arguing that they were “not supported by the existing science.”

The Trump administration and Paxton’s suit both cite a recent scientific review conducted by epidemiologists at Harvard’s T.H. Chan School of Public Health and the Icahn School of Medicine at Mount Sinai. That study, which evaluated existing scientific findings but did not produce new data, found evidence of a link between acetaminophen use during pregnancy and the development of autism and ADHD in childhood.

More than half of the 46 studies included in the review found a positive correlation between use of the drug during pregnancy and neurodevelopmental disorders in children. But scientists have cautioned that the studies do not prove that acetaminophen causes autism, which is known to be linked to a complex interplay of genetics and environmental factors.

Pregnant women who take acetaminophen may differ in important ways from those who don’t, including in their genetics. One major study of nearly 2.5 million children born in Sweden found that, when accounting for the mother’s genetics, there was no association between acetaminophen and neurodevelopmental disorders.

Studies by health agencies — including the FDA and the European Medicines Agency — have evaluated the evidence and found that the results are inconclusive.

On Sunday, Trump again took up the issue on his social media platform, Truth Social. “Pregnant Women, DON’T USE TYLENOL UNLESS ABSOLUTELY NECESSARY,” he wrote.

The main law firm representing plaintiffs in the personal injury cases, Keller Postman, is also serving as outside counsel on Paxton’s suit.

Those plaintiff cases must clear the high bar of showing that the drug caused neurodevelopmental disorders in children and that families should be awarded damages as a result.

But Paxton’s suit pursues a different tack by arguing that Johnson & Johnson and Kenvue violated Texas law by not informing consumers of the possible risks of taking Tylenol during pregnancy.

Texas courts are often challenging for plaintiffs in personal injury cases. Paxton’s decision to file the case in a conservative, rural county near the Louisiana border may have been a strategic move to find a court sympathetic to his case.

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This article originally appeared in The New York Times.

By Rebecca Robbins, Azeen Ghorayshi and J. David Goodman/Haiyun Jiang
c. 2025 The New York Times Company