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I just saw news that leucovorin might be used to treat autism in kids. Is there actually good evidence it helps, or is this more hype than reality?
—Unsure About a Cure
In a September 2025 press conference, President Trump and his medical advisors discussed what they framed as a new “exciting treatment” for treating autism in children: leucovorin. They indicated that they would be starting the process of making this drug more widely available, but provided relatively few additional details about the evidence behind the drug’s efficacy.
Leucovorin, also known as folinic acid, is actually not “new” at all; it’s a decades-old medication that is primarily used in cancer treatment. It treats side effects from a particular chemotherapy drug called methotrexate and is used to enhance the effectiveness of other chemotherapy drugs, colon cancer in particular. There are a number of other related uses, mostly in cancer.
There has been speculation that this medication could help treat autism because individuals with autism are more likely to have cerebral folate deficiency, a condition this medication treats. The fact that it is more common in autistic children than non-autistic children does not necessarily mean that treating it would help, but it suggests a hypothesis to test this.
A number of small randomized controlled trials have provided early results suggesting that, indeed, treatment could improve some symptoms of autism. One of the larger examples is this 2024 study in which 80 children with autism were randomized into a treatment group that received folinic acid and a control group that did not. The treatment group had larger improvements on a scale measure of autism symptoms, which include speech and communication, as well as in behavioral symptoms, relative to the control group. These results were statistically significant.
Another small study found improvement in language skills, concentrated in children with a particular folate status. A 2021 meta-analysis pointed to four randomized studies at that time, along with a number of observational studies, which provided suggestive positive results. In total, fewer than 300 children have been involved in randomized trials for this condition.
Overall, these are interesting and exciting findings and certainly worthy of more research with a few caveats. First, although the effect sizes are meaningful from a research standpoint, they do not imply a “cure” for autism. Second, most of the studies suggest that some individuals benefit more than others, but in ways that are not fully understood. Finally, more work is needed to understand if there are meaningful risks, especially over longer-term dosing.
These studies feel like an exciting first research step. The next step would be a much larger randomized controlled trial with longer follow-up, which would allow researchers to better understand the overall effect and how it varies across individuals. I hope this will happen. Unfortunately, the current plan in the administration is to immediately approve this drug for treating autism and to encourage widespread adoption. This is not the typical approach in these cases and, in fact, may make it more difficult to learn about the actual impact of the medication.
Bottom line: There is a lot of interesting promise here, and I hope that we can continue to learn more, but I’m worried we will not. If we move very quickly to widespread dosing of the medication, it may be difficult to run the kind of careful studies that would help understand who benefits from this. In addition, moving too fast generates risks for side effects, which would otherwise be uncovered in further controlled studies.
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