The Food and Drug Administration (FDA) announced Monday it has begun the process of changing the labeling on acetaminophen to suggest that it may cause autism and ADHD in children whose mothers took the common pain reliever while pregnant.

The announcement followed President Trump’s announcement from the White House in which he repeatedly told pregnant women, “Don’t take Tylenol.”

“Fight like hell not to take it,” said Trump.

Acetaminophen, commonly sold as Tylenol, has been available in the U.S. as an over-the-counter pain reliever and fever reducer for decades. It is one of the few easily available options for pregnant women seeking pain relief.

This new guidance from the Trump administration flies in the face of what numerous medical societies and organizations say reflects the current science.

“In more than two decades of research on the use of acetaminophen in pregnancy, not a single reputable study has successfully concluded that the use of acetaminophen in any trimester of pregnancy causes neurodevelopmental disorders in children,” Steven Fleischman, president of the American College of Obstetricians and Gynecologists (ACOG), said in a statement Monday.

Trump on Tuesday further called on parents not to give acetaminophen to their children, but also indicated he wasn’t absolutely convinced.

When asked about about groups like ACOG pushing back on this claim, Trump said, “You know what? Maybe they’re right.”

“I don’t think they are, because I don’t think the facts bare it out at all. They’re fighting for something that, in my opinion, they shouldn’t be fighting for,” he said. “But here’s the thing, there’s no downside to doing other than a mother will have to, as I say, tough it out a little bit.”

“The FDA is taking action to make parents and doctors aware of a considerable body of evidence about potential risks associated with acetaminophen,” FDA Commissioner Marty Makary said in a statement.

“Even with this body of evidence, the choice still belongs with parents. The precautionary principle may lead many to avoid using acetaminophen during pregnancy, especially since most low-grade fevers don’t require treatment. It remains reasonable, however, for pregnant women to use acetaminophen in certain scenarios.”

Health and Human Services Secretary Robert F. Kennedy Jr. vowed to identify a cause of autism by September of this year, but the FDA noted a causal relationship hasn’t been confirmed between acetaminophen and neurodivergent conditions.

The agency said this move was based on a possible “correlation” between acetaminophen and the diagnoses of autism and ADHD.

“It is important to note that while an association between acetaminophen and neurological conditions has been described in many studies, a causal relationship has not been established and there are contrary studies in the scientific literature,” the FDA said.

Tylenol manufacturer Kenvue disputed the White House’s characterization of its product.

“We believe independent, sound science clearly shows that taking acetaminophen does not cause autism. We strongly disagree with any suggestion otherwise and are deeply concerned with the health risk this poses for expecting mothers,” the company said.

“Acetaminophen is the safest pain reliever option for pregnant women as needed throughout their entire pregnancy. Without it, women face dangerous choices: suffer through conditions like fever that are potentially harmful to both mom and baby or use riskier alternatives.”