As interest grows in new and emerging autism therapies, some families are asking about leucovorin—also known as folinic acid—as a possible treatment. While there has been increasing discussion online and in clinical settings, medical experts emphasize the importance of understanding what the evidence does—and does not—show. 

According to MedPageToday.com, leucovorin is a prescription medication and a highly absorbable form of vitamin B9. It has long been used in oncology to reduce the toxic side effects of certain chemotherapy drugs and to treat specific metabolic conditions. The U.S. Food and Drug Administration (FDA) has approved leucovorin for cerebral folate deficiency (CFD), a rare neurological disorder in which folate cannot effectively cross the blood-brain barrier. Because CFD can include developmental delays and autistic features, leucovorin may significantly improve symptoms in affected individuals by addressing the underlying metabolic issue. 

However, leucovorin is not FDA-approved as a general treatment for autism spectrum disorder (ASD). Research supporting its use in autism remains limited and largely based on small studies, several conducted by the same research group. Some studies have also faced methodological concerns, and experts say larger, well-designed trials are still needed. 

Major medical organizations urge caution. The American Academy of Pediatrics and the Child Neurology Society do not recommend routine use of leucovorin for autistic children without a confirmed CFD diagnosis. Diagnosing CFD typically requires specialized testing, often including a lumbar puncture to assess folate levels in cerebrospinal fluid. Blood tests for folate receptor autoantibodies exist, but their reliability remains debated. 

Some clinicians prescribe leucovorin “off-label,” often using shared decision-making with families. For now, experts advise that families approach this treatment thoughtfully, prioritizing evidence-based care while research continues to evolve.