The Trump administration appears to be walking back its statements from last year that the prescription drug leucovorin can be used to treat certain patients with autism.
The Food and Drug Administration on Tuesday updated the label of leucovorin, a high-dose B vitamin, to list it as a treatment for cerebral folate transport deficiency, an ultra-rare genetic condition, but not autism spectrum disorder, as administration officials promised last September.
FDA Commissioner Marty Makary, standing alongside Health and Human Services Secretary Robert F. Kennedy Jr. and President Donald Trump, had said last fall that leucovorin was “an exciting therapy that may benefit large numbers of children who suffer from autism.”
Makary and other Trump administration health officials said in a September op-ed that the FDA would “approve prescription leucovorin as a treatment for children with cerebral folate deficiency and autistic symptoms.”
But senior agency officials told reporters on Monday that the agency does not have sufficient evidence to support the use of leucovorin for autism symptoms across the spectrum.
Cerebral folate deficiency of the receptor 1 protein, for which the rare disease leucovorin was approved, causes a malfunction in proteins that guide the nutrient folate to the brain. This results in normal levels of folate in the bloodstream but not in the nervous system, where it is critical for speech, thinking, and movement.
Multiple outlets reported that FDA officials said before the label change announcement that the agency did not have sufficient evidence to support the use of leucovorin for patients specifically with an autism spectrum disorder diagnosis.
An HHS spokesperson told the Washington Examiner on Tuesday, following the announcement about leucovorin’s label change, that the September 2025 announcement was about treating symptoms associated with autism, such as speech and cognitive development delays, rather than treating autism spectrum disorder as such.
“This treatment is for a specific medical condition that can cause developmental delays with autistic symptoms rather than autism spectrum disorder, which obviously is a very complicated condition that requires a multi-disciplinary treatment approach,” the department spokesperson said via email.
The spokesperson said that cerebral folate transport deficiency “is not the same thing as autism.”
Makary made the announcement about leucovorin last September during a press conference, during which he also alleged that acetaminophen, the active ingredient in the painkiller Tylenol, is a likely cause of autism through exposure during pregnancy.
During the press conference last fall, Makary said, “Autism may also be due to an autoimmune reaction to a folate receptor on the brain, not allowing that important vitamin to get into the brain cells.”
He described leucovorin as a drug from which “hundreds of thousands of kids” could benefit.
Small studies have indicated that leucovorin could improve symptoms in children with folate deficiency or certain autism symptoms, including improving speech.
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But a 2024 paper supporting the connection between supplemental folate and improving autism symptoms was recently retracted by the European Journal of Pediatrics after errors were identified post-publication.
The Washington Examiner contacted HHS for comment.
