The Trump administration is expected to link autism to Tylenol use during pregnancy

The Trump administration is expected to assert later today that use of acetaminophen — the active ingredient in Tylenol — can increase the risk of autism when used during pregnancy, despite the fact that scientific research has not conclusively demonstrated a causal link.

White House officials are also expected to suggest that a form of vitamin B that is typically used in conjunction with cancer treatment could be used to treat autism.

“We’re gonna have one of the biggest announcements, really, medically, I think, in the history of our country,” President Trump said Sunday night, referring to a press conference scheduled for Monday afternoon. “I think we found an answer to autism.”

This would be the administration’s latest move questioning the science of commonly used medications, from vaccines to abortion medications, and stirring up controversy in what many say is an effort to undermine the scientific establishment and advance a political agenda.

Autism has long been a target for Health and Human Services Secretary Robert F. Kennedy Jr. Shortly after taking office, he pledged to swiftly identify the cause “by September,” and has cited the use of everything from synthetic food dyes, childhood vaccines, and painkiller use as potential culprits.

But while autism diagnoses have tripled in the past two decades, the use of acetaminophen has not — remaining largely steady over that time.

In addition, scientists agree that genetics play a central role in a child’s risk of developing autism. The disorder runs in families, and if one identical twin is on the spectrum, most of the time the other will be too.

A few small studies have suggested an association between fetal exposure to acetaminophen and the subsequent risk of diagnosis with autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD). But the largest study to date, an NIH-funded collaboration between U.S. and Swedish scientists, found no increased risk.

Even before that study was published in 2024, a U.S. District Court had reached a similar conclusion in a product liability case.

Meanwhile, groups like the Society for Maternal-Fetal Medicine have stood by recommendations to use acetaminophen to treat fever and pain in pregnant women. The group argues that untreated fever, for example, can cause grave harms such as miscarriage, birth defects or premature birth, especially early in a pregnancy.

The administration is also expected to say in its report that leucovorin or folinic acid — a form of vitamin B that is sometimes used to treat deficiencies caused by chemotherapy — could prevent or treat the disorder. The use of leucovorin is based on research suggesting that many people with autism have a metabolic difference that could reduce the amount of folate that reaches the brain. Leucovorin appears to offer a way around that metabolic roadblock.

And although leucovorin affects a system that is important for brain and nervous system development and is sometimes prescribed off-label as a treatment for autism, the evidence that it works is scant.

The Autism Science Foundation said in a statement last week that there are four studies suggesting low folate levels in pregnant women could increase the risk of autism, but it said “this science is still in very early stages, and more studies are necessary before a definitive conclusion can be reached.”