Just six months ago, the Trump administration promised to find the cause of autism. On September 22, top U.S. health officials announced both a cause and a treatment — though neither is on solid scientific footing, and no data were presented to back up the claims.

In an hour-long news briefing filled with inaccuracies, President Donald Trump claimed that acetaminophen, commonly sold in the United States as Tylenol, can cause autism, and repeatedly told pregnant people not to take it. And he claimed a drug called leucovorin, a form of folinic acid used to help counter the toxicity of chemotherapy, can treat symptoms.

“We’re going to save a lot of children from a tough life, a really tough life. We’re going to save a lot of parents from a tough life,” Trump said.

Yet evidence is scant that acetaminophen, a widely available drug for fever and pain, has any relationship to autism, much less that the drug can cause autism. And it’s too soon to say whether the drug leucovorin holds promise, many autism experts say.

“The data cited do not support the claim that Tylenol causes autism and leucovorin is a cure, and only stoke fear and falsely suggest hope when there is no simple answer,” the Coalition of Autism Scientists, a group of more than 250 autism researchers, said in a statement.

Autism rates are rising. As of 2022, an estimated 1 in 31 kids were diagnosed with autism by the time they were 8. The Trump administration has claimed that this increase must be driven by some sort of toxin or exposure, despite evidence that increased awareness and screening are behind the rise.

The relationship between acetaminophen and autism is one of those potential exposures that’s been studied. A recent review of scientific literature, published August 14 in Environmental Health, described studies that found an association between acetaminophen during pregnancy and later risk of autism. “But even [the authors of that review] say you can’t establish any sort of causality from those studies,” says Dennis Kuo, a pediatrician at the University of Rochester Medical Center in New York.

A large study published in JAMA last year found no association between acetaminophen during pregnancy and autism, attention-deficit/hyperactivity disorder or intellectual disability. In that study of nearly two and a half million children in Sweden, “they verified the exposure [to acetaminophen], they quantified the exposure, and they did very, very good follow-up,” Kuo says. When the researchers compared siblings, one with autism and one without, any connection between acetaminophen during a mother’s pregnancy and a later autism diagnosis disappeared. That comparison was key, Kuo says, because it suggests that other factors — not acetaminophen — were behind the purported link. “There’s no association.”

Even if such an association consistently turned up, that link wouldn’t necessarily mean that acetaminophen causes autism, says Noor Pervez, a community engagement manager at the Autistic Self Advocacy Network, a nonprofit organization based in Washington, D.C.

For one thing, autism is strongly genetic. What’s more, autistic people are at higher risk of certain health conditions that come with chronic pain, such as migraine, Pervez points out. “Autistic parents are more likely than non-autistic parents to have autistic children,” Pervez says. “So it is possible that parents with autistic traits are more likely than non-autistic parents to take Tylenol during pregnancy, and it is the parents’ autism, not the medicine, that contributes to a greater likelihood that the child will be autistic.”

Rhetoric that blames a parent for autism is harmful, Kuo says. “Autism is not something that a parent did or didn’t do.”

Pervez points out the harm such messages can cause. “Parents will think their actions are to blame for a child’s disability,” he says. “This is both not true and promotes stigma about autism.”

And reducing autism to a single cause is not realistic. “It’s so complex and there’s so many factors that could potentially go into it,” Kuo says. Claiming to have found a simple cause “is just not giving all of the research that’s already been done the attention it needs.”

In his remarks, President Trump told pregnant women to “tough it out.” “Don’t take Tylenol,” he said, over and over. “There’s no downside.”

But there is. Acetaminophen is one of the few options available to pregnant people for pain and fever, both of which can bring medical danger, Steven J. Fleischman, president of the American College of Obstetricians and Gynecologists, noted in a statement. “The conditions people use acetaminophen to treat during pregnancy are far more dangerous than any theoretical risks and can create severe morbidity and mortality for the pregnant person and the fetus.”

Fevers during pregnancy also have been tied to increased risk of disorders including autism and schizophrenia.

What’s more, foregoing pain relief will lead to suffering, Pervez points out. “These claims will also lead some pregnant people, including pregnant autistic people, to needlessly suffer by convincing them that the painkiller most commonly used during pregnancy is not safe.”

Also in the Sept. 22 announcement, the nation’s top health officials pointed to a drug that they claim will treat autism symptoms, also with no new evidence to back it up. The drug, called leucovorin, will be relabeled to treat people with autism who may have too little folate getting into their brain.

“We have a duty to let doctors and the public know we’re going to change the label to make it available,” U.S. Food and Drug Administration Commissioner Marty Makary, said in the news briefing. “Hundreds of thousands of kids, in my opinion, will benefit.”

Widespread treatment of children with this drug, which is a form of folinic acid, is premature, says Kevin Klatt, an expert in folate science at the University of California, Berkeley. “I would say don’t kill the hypothesis, but it’s early stage research,” he cautions.

Studies that have been done with autistic children so far have been small and mainly from one group of researchers, Klatt says. There have been no large clinical trials conducted on leucovorin. “To be serious about this, they should put $10 million behind a large, randomized controlled trial, multi-center,” Klatt says. “Or have a call for those applications, and have people go in and really say, ‘Does this hold any promise?’”

Rushing this drug out may “provide false hope,” Klatt says. “I’ve already seen pregnant women in my DMs asking me about, ‘How do I get folinic acid?’” He’s concerned that people will seek out unregulated folate supplements, also called vitamin B9, that may claim to do the same thing as leucovorin.

The process behind this change is flawed, Klatt says. “It’s like, well, if you really love science so much, why are you trying to take an experimental therapy with a signal for maybe it will do something, and mainstream it in American medicine?”

Beyond the dearth of scientific and medical evidence, the announcement heavily framed the idea of autism as an “epidemic,” one that is in desperate need of a solution.

This lens ignores what many autistic people need, Pervez says. “By focusing on ‘cure’ rhetoric, we’ve effectively seen people ignore the last 30 plus years in autism research. Autistic people, generally speaking, don’t want a cure. We want to be able to live our lives in our communities, as part of them. You don’t get there by ignoring our wishes and treating us existing as inherently bad.”