The Promise and Pitfalls of Leucovorin for Autism Symptoms

A Surge in Off-Label Use

In March 2026, the FDA approved leucovorin, a folate-based drug, for treating cerebral folate deficiency—a rare genetic condition. However, the agency explicitly excluded autism spectrum disorder (ASD) as an approved indication, despite earlier speculation that the drug might help with autism symptoms. This decision hasn’t stopped a surge in off-label prescriptions for leucovorin in autism, according to research from UC San Diego.

Leucovorin, also known as folinic acid, has been explored in small clinical trials like this 2018 study (N=48) showing modest language improvements in some autistic children, though the study lacked a control group. An ongoing clinical trial (NCT02839915) with 100 participants is investigating leucovorin’s effects on language differences in ASD using a double-blind, placebo-controlled design, but results aren’t expected until late 2027.

Currently, only two drugs—risperidone and aripiprazole—are approved for autism-related irritability, as noted in a 2021 review.

The Evidence Gap

The FDA’s rejection of an autism indication for leucovorin highlights a broader issue: the lack of FDA-approved medications targeting core autism characteristics like communication and social interaction differences. Currently, only two drugs—risperidone and aripiprazole—are approved for autism-related irritability, as noted in a 2021 review. These medications don’t address core autism characteristics, and their use can be limited by side effects like weight gain and sedation.

Pharmacogenomic research is advancing in preclinical stages, offering theoretical hope for more personalized treatments. A recent minireview in Frontiers in Pharmacology explored how genetic differences might influence responses to risperidone, but this work remains years away from clinical application.

Preclinical Promise, Human Challenges

Preclinical studies using animal models have identified potential drug candidates for autism. A systematic review in Nature highlighted several promising approaches, including drugs repurposed from epilepsy treatments. However, translating these findings to humans has proven difficult due to autism’s heterogeneity, as noted in Yale zebrafish research.

The disconnect between preclinical optimism and clinical reality underscores autism’s complexity. While leucovorin and other repurposed drugs offer hope, experts urge caution due to potential risks like gastrointestinal side effects and lack of proven efficacy. As CNN reported, the FDA’s decision reflects a need for more rigorous evidence before widespread use.

Ethical Considerations and Next Steps

For now, families and clinicians navigate a landscape of limited options with important ethical considerations. The Autism Self-Advocacy Network emphasizes that treatment decisions should prioritize autistic individuals’ needs and autonomy. The allure of off-label treatments like leucovorin is understandable, but the lack of robust data means risks and benefits remain unclear. As research continues, the hope is for more targeted, evidence-based supports to emerge—ones that respect neurodiversity while addressing specific challenges.