Last September, President Donald Trump, Robert F. Kennedy Jr., and some health officials announced they had found a potentially revolutionary treatment for autism spectrum disorder (ASD) using leucovorin, a medication already on the market. A new study reveals that many families were influenced by this statement.
Researchers from the University of California, San Diego, investigated prescription trends of leucovorin last year. They noticed a dramatic increase in prescriptions for children with autism, especially after that September announcement. This suggests, according to the researchers, that Trump’s endorsement had a considerable impact on families, even though there is little data backing the drug’s efficacy.
“Families of children with ASD often look for therapies to improve their quality of life, especially when they have limited options,” said Joshua Rothman, the study’s lead author and a clinical assistant professor at UCSD. “While a few small studies hint at promise, we don’t have solid evidence to recommend this treatment universally for all children with ASD.”
The Trump Effect
The September announcement primarily addressed acetaminophen (Tylenol). At that time, officials claimed a connection between women taking acetaminophen during pregnancy and an elevated risk of autism in their children. Many experts disagreed with this assertion, and new studies have continued to dispel this view. During the same conference, leucovorin was promoted as a possible autism treatment.
Leucovorin is a form of folate, or vitamin B9, crucial for several functions, including healthy fetal development. While it’s traditionally used to manage side effects from certain cancer therapies, it has also become a standard treatment for cerebral folate deficiency, a condition where folate can’t normally reach the brain. Unlike other folate forms, leucovorin effectively penetrates the brain and can reverse this deficiency.
Some limited studies have indicated that children with autism may have lower levels of folate in their brains, and symptoms of cerebral folate deficiency can mimic severe autism. Based on these tenuous connections, RFK Jr. touted leucovorin in September as a promising therapy that could help “large numbers of children” with autism. Former FDA Commissioner Marty Makary even stated it might assist “hundreds of thousands of kids,” suggesting it could potentially benefit up to “50% of kids with autism” with this deficiency.
Recognizing the significant attention garnered by the September announcement, Rothman and his team sought to analyze its impact on leucovorin prescriptions. They examined medical records from EPIC Cosmos, which holds over 300 million patient records from health systems across the U.S., tracking prescription rates among over 800,000 children with autism from January 2023 to January 2026.
A Fox News report in February 2025 also contributed to the growing interest in leucovorin, highlighting families who believed the drug helped improve their children’s symptoms, particularly in speech.
Rothman and his team observed a noticeable increase in leucovorin prescriptions following the Fox News report, with an even more significant spike after the Trump announcement. In 2023 and 2024, there were about 34 prescriptions per 100,000 outpatient visits for children with autism. By November 2025, that figure jumped to 835 prescriptions per 100,000 visits.
“We found that prescriptions of leucovorin for children with ASD increased by over 2,000% following extensive media coverage and statements from White House officials,” Rothman stated. Their findings were published in JAMA Network Open.
A Drug Without Strong Evidence
Since the initial announcement, the Trump administration has somewhat distanced itself from its strong endorsement of the drug.
In early March, the FDA approved the broader use of leucovorin for treating cerebral folate deficiency but pointedly did not endorse it for autism treatment, citing a lack of robust evidence to support such a decision.
Overall data supporting leucovorin’s effectiveness for autism has always been weak, and it appears to be getting weaker. Earlier this year, a journal retracted a positive trial of leucovorin supplements in children with autism after issues were found with the data, raising concerns. This trial was the largest conducted to date, involving 77 children and was one of only five trials total.
The study led by Rothman and his colleagues doesn’t aim to determine leucovorin’s usefulness for autism. However, given the growing number of families getting this prescription, more research is needed, Rothman argues.
“It would be beneficial to evaluate outcomes and share these results, especially since prescriptions for leucovorin have surged among children with ASD,” he noted. The team hopes future research will look into the long-term outcomes for families using leucovorin for autism.
“As scientists and clinicians, we have a responsibility to gather the rigorous data necessary to help families and clinicians make informed choices,” he concluded.
