Lead: In March 2026, the U.S. Food and Drug Administration declined to expand approval of the generic drug leucovorin for use in treating autism, instead approving it only for a rare genetic condition, cerebral folate deficiency caused by FOLR1 mutations in adults. The decision follows high-profile promotion of the drug by FDA Commissioner Marty Makary and other Trump administration officials in September, which coincided with a sharp rise in outpatient prescriptions for children. Regulators told the Associated Press that the agency saw insufficient evidence to endorse leucovorin as an autism treatment. The FDA’s narrow approval underscores a split between political messaging and the agency’s evidence-based review.
Key Takeaways
- In September 2025, senior administration officials promoted leucovorin as a promising autism therapy; Commissioner Marty Makary publicly suggested it might help “20, 40, 50 percent of kids with autism.”
- A Lancet-published analysis found outpatient prescriptions of leucovorin for children aged 5–17 rose 71% in the three months after the administration’s actions.
- The FDA approved leucovorin only for cerebral folate deficiency (CFD) in adults caused by FOLR1 mutations—not for autism—citing limited evidence for broader use.
- Senior FDA officials told the Associated Press they found “little evidence for expanding the drug’s use to autism,” leading to a restricted regulatory decision.
- Promotional statements from political leaders appear to have influenced prescribing behavior despite the absence of robust, autism-specific randomized controlled trial data.
- Off-label use in pediatric autism remains legally permissible for clinicians but now lacks an FDA-backed indication, affecting payer coverage and clinical guidelines.
- The episode highlights tensions between political advocacy and regulatory standards for drug indications and the potential public-health consequences of premature endorsement.
Background
Leucovorin (folinic acid) is a well-known, inexpensive folate derivative used clinically for several indications, including as a rescue after methotrexate and to treat certain folate metabolism disorders. For years, a subset of clinicians and some parent advocates have sought broader use of folate-pathway agents, including leucovorin, as off-label interventions for autism spectrum disorder (ASD), arguing biological subtypes of ASD might respond to metabolic treatments. Evidence supporting those claims has been mixed, with small trials and case series but no large, definitive randomized controlled trials showing consistent benefit across the broad autism population.
The U.S. regulatory process separates political statements from the technical review that determines drug labeling. In September 2025, the Trump administration staged events promoting “bold actions” on autism and spotlighted leucovorin as a candidate therapy. Those messages reached clinicians and families quickly, as prescribing data later showed. The FDA’s formal approval pathway, however, requires substantial evidence of safety and efficacy for a specific indication; that standard underlies the agency’s March 2026 decision to restrict the approval to a genetically defined adult condition, not ASD.
Main Event
The controversy began with high-profile promotion in September 2025. At a White House event, FDA Commissioner Marty Makary and other officials described leucovorin as having mounting supportive evidence and suggested sizable benefit rates for children with autism. Makary told the press that a broad share of children could respond, citing percentages and estimating large numbers of beneficiaries.
Following that publicity, a study published in The Lancet documented a 71% increase in new outpatient leucovorin prescriptions for children ages 5–17 in the three months after the administration’s statements. The spike suggests rapid translation of political messaging into prescribing patterns, particularly for off-label use in pediatric populations.
On March 2026, the FDA issued an announcement detailing its approval decision: leucovorin was approved for use in adults with cerebral folate deficiency caused by pathogenic variants in the FOLR1 gene (CFD-FOLR1). The agency explicitly declined to broaden the approval to autism, citing insufficient evidence that the drug improves autism-related core symptoms across the heterogeneous ASD population.
Senior FDA officials spoke to the Associated Press to explain the rationale, saying reviewers found little evidence to support expanding the drug’s labeled use to autism. The agency narrowed its regulatory review to the genetically defined CFD-FOLR1 indication where trial or observational data met the threshold for approval.
Analysis & Implications
The FDA’s decision separates an evidence-based regulatory judgment from politically driven promotion. When high-level officials publicly endorse a treatment before robust clinical proof exists, clinicians and families can act on those statements, creating rapid shifts in prescribing that outpace evidence and guideline development. The 71% rise in pediatric prescriptions after September indicates how quickly off-label use can increase when amplified by political attention.
For clinicians, the ruling leaves a practical dilemma. Off-label prescribing remains allowed and in some cases clinically reasonable, particularly when caregivers request treatments for which limited evidence exists. However, an FDA approval affects insurance coverage, clinical guidelines, and liability considerations; without an autism indication, many payers are unlikely to reimburse leucovorin for ASD, shifting costs to families and potentially exacerbating inequities.
For researchers and funders, the episode underscores the need for well-powered randomized trials that target biologically defined subgroups within autism, rather than blanket approaches. The FDA’s approval for CFD-FOLR1 highlights a precision-medicine pathway: when a clear genetic mechanism links to metabolic disturbance, targeted treatment can meet regulatory thresholds. Whether similar, replicable subgroups can be defined in ASD remains an open research challenge.
Politically, the divergence between administration messaging and the FDA’s technical conclusion may prompt internal and public scrutiny of how health recommendations are communicated. The incident could lead to calls for clearer boundaries between agency science and political advocacy, and for stronger channels to prevent premature endorsements from driving clinical practice absent sufficient evidence.
Comparison & Data
| Metric | Pre-September 2025 | Post-September 2025 (3 months) |
|---|---|---|
| New outpatient leucovorin prescriptions (ages 5–17) | Baseline (index) | +71% relative increase |
| Regulatory status for autism | Not approved | Still not approved |
| Regulatory status for CFD-FOLR1 (adults) | Not approved | Approved (March 2026) |
The table summarizes the key quantitative signal— a 71% increase in new pediatric prescriptions after high-profile promotion—alongside the unchanged regulatory stance on autism and the new approval for a narrowly defined adult genetic condition. That juxtaposition illustrates how prescribing behavior can change rapidly while the evidence base and labeling do not.
Reactions & Quotes
“It might help 20, 40, 50 percent of kids with autism,”
Marty Makary, FDA Commissioner (at White House event)
Makary’s public projection of possible response rates was a central catalyst for media attention and public expectation, cited repeatedly by clinicians and families seeking options.
“Hundreds of thousands of kids, in my opinion, will benefit,”
Marty Makary, FDA Commissioner (White House remarks)
That broader claim of population-level impact amplified demand and likely contributed to the observed prescription spike documented by researchers.
“We found little evidence for expanding the drug’s use to autism,”
Senior FDA officials (comments to Associated Press)
FDA reviewers emphasized that available studies did not meet the threshold for labeling a treatment for ASD, prompting the agency to confine approval to a defined genetic folate-receptor disorder.
Unconfirmed
- Exact number of children who will receive leucovorin off-label for autism nationwide remains unverified; prescription data show a surge but not absolute counts.
- The proportion of children with autism who might benefit from leucovorin (the “20–50%” range cited by officials) is unproven and not supported by large-scale trials.
- Long-term safety and developmental impact of routine leucovorin use in broad pediatric ASD populations are not established.
Bottom Line
The FDA’s March 2026 decision draws a clear line between political promotion and the agency’s scientific standard: leucovorin is approved for a narrowly defined adult genetic folate-receptor disorder (CFD-FOLR1) but not for autism. The gap between public statements and regulatory evidence has already changed prescribing behavior, illustrated by a 71% rise in pediatric prescriptions following the administration’s September messaging.
For families and clinicians, the ruling means off-label use remains an option but without the regulatory, reimbursement, and guideline support an indication provides. Policymakers and health leaders should consider mechanisms to prevent premature endorsement of therapies before sufficient evidence is available, while researchers should prioritize rigorous trials to test targeted hypotheses about metabolic subtypes within autism.
Sources
- Ars Technica (technology and science reporting)
- U.S. Food and Drug Administration (official regulatory announcements)
- The Lancet (peer-reviewed academic journal; analysis of prescribing trends)
- Associated Press (news reporting; FDA official comments)