The over-the-counter drug has been used in Tylenol and many other other widely used medications for decades as a pain and fever reliever during pregnancy.

Donald Trump said Monday the Food and Drug Administration approved a chemotherapy drug called leucovorin as a treatment to alleviate symptoms of autism, despite little evidence that the medication works.

Trump also said the administration is issuing a warning to doctors not to recommend acetaminophen — the active ingredient in Tylenol and other widely used medications — for pregnant women, claiming it may be linked to autism in children.

Trump had been teasing the announcement for days, as Health Secretary Robert F. Kennedy Jr. and other health officials have pledged to determine the cause of the developmental disorder by September.