US regulators say there is not enough strong evidence to support claims that a drug promoted by former President Donald Trump could help most people with autism.
On Tuesday, the US Food and Drug Administration (FDA) approved the drug leucovorin, but only for a very rare brain disorder linked to low levels of folate in the brain.
Officials estimate that the genetic condition affects fewer than one in a million people in the United States.
The decision marks a step back from earlier statements made during a White House news conference last September.
At the event, Trump and FDA Commissioner Marty Makary said the drug was being reviewed because it might help children with autism.
According to AP News, Makary said at the time that the condition treated by the drug "might be 20, 40, 50% of kids with autism."
However, senior FDA officials said this week that their scientific review focused only on the strongest available data. That evidence showed the drug may help patients who have the rare mutation that blocks folate, a type of vitamin B, from reaching the brain.
The agency also noted that one research study supporting the drug's use for autism was retracted earlier this year, raising further concerns about the reliability of the evidence.
The Trump administration did an about-face Tuesday on an autism treatment it had promoted with great fanfare.
— Yahoo News (@YahooNews) March 10, 2026
It had said back in September it would approve use of a drug called leucovorin - synthetic vitamin B9 - to treat the disorder. But on Tuesday the FDA backed off, citing… pic.twitter.com/ck5HP83bq5
Doctors Say Autism Drug Evidence Is Weak
Autism researchers say the drug has not been proven safe or effective for most people with autism.
Alycia Halladay of the Autism Science Foundation said there is still little proof that the medication works broadly.
"There is no evidence to say that leucovorin will help most people with autism, and there's certainly no evidence to say it's safe," Halladay said.
Leucovorin is a synthetic form of folate and has long been used for other medical purposes. The FDA already allows it to help reduce side effects from certain chemotherapy drugs and to treat a rare blood disorder.
Patients with the newly approved brain condition can experience seizures, movement problems, and other neurological symptoms that sometimes resemble autism.
But experts say it remains unclear whether the drug can truly improve autism symptoms.
Major medical groups, including the American Academy of Pediatrics, do not recommend routine use of leucovorin for autistic children.
Despite the uncertainty, prescriptions for the drug have risen sharply.
A recent paper published in The Lancet found that prescriptions for children ages 5 to 17 increased by 71% in the three months after Trump's September announcement, LasVegasSun reported.
David Mandell of the University of Pennsylvania said the early publicity created confusion for many families.
"We've seen huge increases in leucovorin prescriptions for autism because of the initial premature and ill-informed announcement," he said.
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