Use of Leucovorin After the FDA Announcement of Its Use for Autism Spectrum Disorders

BACKGROUND AND OBJECTIVES: Leucovorin, or folinic acid (vitamin B9), is approved by the Food and Drug Administration (FDA) to reduce adverse effects from antifolate cancer treatments including methotrexate. In September 2025, the FDA announced that it would expand the label of leucovorin to include treating an extremely rare neurologic condition, cerebral folate deficiency, which shares some symptoms with autism spectrum disorder (ASD).1 The FDA's announcement was accompanied by a widely-publicized White House press conference in which the use of leucovorin for ASD was touted and was preceded by national media reports of the potential benefits of leucovorin for treating ASD in February 2025.2 We measured changes in leucovorin prescriptions in the US during this period of heightened political attention and media coverage.