Following a White House press conference suggesting leucovorin as a treatment for autism in September 2025, and despite a lack of supporting data, US prescriptions of the drug soared, according to a paper published yesterday in The New England Journal of Medicine (NEJM). 

“Our findings suggest the press conference may have increased off-label prescribing of leucovorin to children with autism,” lead author Kao-Ping Chua, MD, PhD, from the University of Michigan School of Public Health, said in a press release. “This increase is concerning because the effectiveness and long-term safety of leucovorin for children with autism is uncertain.” 

700% increase in 2025

Leucovorin is a folic acid analog that doctors use to help patients who have side effects from methotrexate, a drug that treats some cancers and autoimmune conditions. Leucovorin isn’t approved to treat autism, but the US Food and Drug Administration has said it can be used for children with cerebral folate deficiency.

Cerebral folate deficiency is “a rare disorder that can mimic symptoms of autism,” Michael Barnett, MD, of Brown University, and Jeremy Faust, MD, of Mass General Brigham, said in a commentary on a previous study in JAMA Network Open in June. 

To understand prescribing trends of leucovorin, in the NEJM study, researchers examined data from the IQVIA Longitudinal Prescription Database, which tracks 93% of prescriptions from retail pharmacies, from December 29, 2024, to December 14, 2025. 

Prior to the press conference, leucovorin prescriptions increased from 1.0 per 100,000 children to 4.6 per 100,000. Following the press conference, the number of prescriptions increased 46%, from 4.6 per 100,000 children to 6.7 per 100,000. By the end of the study, prescriptions had risen to 8.0 per 100,00 children