Mr. 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 Mr. Trump’s allegations that the use of acetaminophen products like Tylenol during pregnancy could cause neurodevelopmental disorders. The issue has been a longstanding concern among some followers of Robert F. Kennedy Jr., the nation’s top health official, but the idea gained traction with Mr. Trump’s remarks.