Leucovorin for Autism: What Parents Should Know in 2026

Leucovorin for autism is not an approved or proven treatment. Leucovorin (folinic acid) is a prescription form of folate. In March 2026 the FDA approved it only for a very rare genetic brain-folate condition, not for autism. A few small trials suggest some autistic children may improve, but the evidence is limited, and one key trial was retracted.

Folate, folic acid and folinic acid: what is the difference?

Folate is a B vitamin (B9) that the body needs to make DNA and to support brain development. “Folate” is the general name for the forms found in food, supplements and fortified foods. Folic acid is the man-made form added to flour and used in most vitamins [19].

Folinic acid, sold as the medicine leucovorin, is a “reduced” form of folate. The body can use it without first converting it with an enzyme called DHFR. This is why it can still work when normal folate pathways are blocked [7]. In the US it is a prescription drug, and the AAP notes it is more readily used by the body than over-the-counter folate supplements [7].

Leucovorin’s long-standing medical uses

Leucovorin has been used for decades, mostly in cancer care. Approved uses include protecting patients from the toxic effects of high-dose methotrexate (a cancer drug), treating overdoses of folate-blocking drugs, treating megaloblastic anemia caused by folate deficiency when folic acid by mouth is not possible, and boosting the cancer drug fluorouracil (5-FU) in advanced colorectal cancer [5]. Because cancer patients rely on it, oncologists have raised concerns that extra demand could worsen existing leucovorin shortages [22].

What is cerebral folate deficiency (CFD)?

Cerebral folate deficiency means the brain and spinal fluid have too little active folate, even though blood folate levels are normal [7][15]. It usually shows up in infants and young children. Signs can include developmental delay or loss of skills, seizures, movement or muscle-tone problems, slowed head growth and autistic features [7].

The most reliable test measures a form of folate called 5-MTHF in spinal fluid, which needs a lumbar puncture (spinal tap). A normal blood folate result does not rule CFD out [7].

The FOLR1 gene

Folate gets into the brain partly through a “doorway” protein called folate receptor alpha. The instructions for this protein are in the FOLR1 gene. In 2009, researchers described children with harmful FOLR1 variants who had very low spinal-fluid folate, seizures, movement problems and loss of skills, and who improved with folinic acid [16]. This inherited form is extremely rare. The FDA estimates it affects fewer than one in a million people in the US [25].

Folate receptor autoantibodies (FRAA) and the FRAT test

A second suspected cause of CFD is the immune system making antibodies that block folate receptor alpha. These are called folate receptor alpha autoantibodies, or FRAA. A 2005 study found these antibodies in 25 of 28 children with CFD, and folinic acid raised their spinal-fluid folate [15].

Some autism studies report that FRAA are common in autistic children [13]. A blood test sold as the Folate Receptor Antibody Test (FRAT) looks for them. However, there is no FDA-cleared FRAA test, testing is not standardized, and the AAP says results should not be used alone to make decisions [7]. The Society for Developmental and Behavioral Pediatrics (SDBP) has called current FRAT testing unreliable [17]. Testing for common MTHFR gene variants is also not useful for diagnosing CFD [7].

What happened in 2025 and 2026

On September 22, 2025, the FDA and the US Department of Health and Human Services (HHS) announced plans to update leucovorin’s label for cerebral folate deficiency, saying people with CFD “have been observed to have developmental delays with autistic features” [1][2]. HHS said leucovorin “is not a cure” for autism [2]. The FDA itself noted “limitations on the available data” for the wider group of people with autistic features and FRAA, and said more studies were needed [1].

Interest grew quickly. One study of US health records found leucovorin prescriptions for autistic children were already rising in early 2025 and peaked in November 2025 at more than 24 times their 2023 to 2025 average [20].

On March 10, 2026, the FDA approved Wellcovorin (leucovorin calcium) tablets for “cerebral folate transport deficiency in adult and pediatric patients who have a confirmed variant in the folate receptor 1 gene (FOLR1-CFTD)” [3][4]. The approval was based on a review of published case reports and how the drug works, not on a new clinical trial [3]. It is not an approval of leucovorin for autism.

Leucovorin for autism: what the trials show

The main controlled studies are all small and short.

• Frye and colleagues, 2018 (US). 48 autistic children with language delays (average age about 7) received high-dose folinic acid or placebo for 12 weeks. Verbal communication improved more with folinic acid, especially in children who tested positive for FRAA. Side effects did not differ between groups [8]. As of October 2026 we found no retraction or correction for this paper.
• Renard and colleagues, 2020 (France). A pilot trial of 19 children using a lower fixed dose for 12 weeks. Autism observation (ADOS) scores improved more with folinic acid than placebo. The authors said a larger trial is needed [9].
• Batebi and colleagues, 2021 (Iran). 55 autistic children (average age about 13) took folinic acid or placebo alongside risperidone for 10 weeks. Some behavior scores improved, but irritability and social withdrawal did not differ from placebo [10].
• Zhang and colleagues, 2025 (China). 80 children were randomized for 12 weeks. Both groups improved, and the folinic acid group improved more on only one area, social reciprocity [14].

The 2026 retraction

A 2024 trial from India in the European Journal of Pediatrics included 80 children aged 2 to 10 and was one of the largest leucovorin trials. In early 2026 the journal retracted it. An independent statistical review “was unable to replicate the results” from the authors’ data, and the editor no longer had confidence in its conclusions [11]. The SDBP responded by calling for high-quality, reproducible evidence before practice changes [12].

Reviews of the evidence

A 2021 systematic review and meta-analysis found 21 studies that treated autistic people with leucovorin, including only four placebo-controlled trials. It concluded leucovorin was associated with improvements and was generally well tolerated [13]. Note that its two authors also led some of the trials it reviewed. A 2026 review concluded that clinical evidence remains limited, that long-term safety and benefit data are lacking, and that larger, well-designed studies are needed [21].

New randomized, blinded trials are recruiting, including one in Singapore planning 184 children and another planning 150 [23][24]. Their results should give clearer answers.

What professional groups say

• American Academy of Pediatrics: In interim guidance (October 31, 2025), the AAP “does not recommend the routine use of leucovorin (folinic acid) for autistic children.” It encourages shared decision-making, has no prescribing guideline for autism, and says families should keep well-established supports and therapies [6]. Its FAQ adds that current evidence does not support prescribing leucovorin for autism without CFD [7].
• Society for Developmental and Behavioral Pediatrics: Says “definitive recommendations about leucovorin treatment cannot be made without more rigorous studies” [17].
• American College of Medical Toxicology: In July 2026, it said it supports leucovorin for autism only within clinical research until more data exist [18].

Leucovorin side effects and safety

Side effects in autism studies were usually mild. Across studies, the most common were excitement or agitation (about 12%), aggression (about 10%), trouble sleeping (about 9%), increased tantrums (about 6%) and headache (about 5%) [13]. The AAP also lists irritability, stomach upset such as nausea or diarrhea, skin problems and, rarely, serious allergic reactions [7].

Other important safety points:

• Seizure medicines. High-dose folate may make some anti-seizure drugs, such as phenobarbital, phenytoin and primidone, work less well, so children on these need close monitoring [4].
• Vitamin B12. Leucovorin can hide signs of B12 deficiency in the blood while nerve damage continues [4].
• A rare metabolic disorder. Leucovorin should not be used in MTHFS deficiency, where it can worsen symptoms [7].
• Unknowns. Best dose, how long to treat and the risks of long-term high-dose use are not known [7].

Studies of leucovorin for autism used weight-based doses, and the FDA label for FOLR1-CFTD is also weight-based [4][8]. Only your child’s doctor can advise whether any dose is right. Please do not buy “folinic acid” online or self-dose. Supplement makers, not the FDA, are responsible for checking safety before sale [26], and an unmonitored child may have side effects or drug interactions that go unnoticed. For more on spotting risky claims, see our guide to unproven autism treatments to avoid.

What you can do: questions to ask your child’s doctor

If you are wondering about leucovorin for autism, it is reasonable to raise it at your next visit. Questions that may help:

1. Does my child have any signs that suggest a folate or metabolic problem, such as seizures, loss of skills, movement problems or slowed head growth?
2. Would genetic testing help us look for a cause, including FOLR1? (See our guide to genetic testing for autism.)
3. Should we see a child neurologist or metabolic specialist?
4. What would an FRAA blood test tell us, and how reliable is it?
5. If we tried leucovorin, what goal would we measure, how long would we try it, and when would we stop?
6. Could it interact with my child’s other medicines or supplements?
7. How do we keep speech, occupational and other therapies going at the same time?

When testing might be considered

According to the AAP, doctors may suspect CFD when a young child has features such as developmental regression, seizures, movement or tone problems, slowed head growth or abnormal brain MRI findings, and may refer to a specialist [7]. Testing is not recommended for every autistic child.

Red flags of hype

• Claims that leucovorin “cures” or “reverses” autism.
• Websites selling tests and treatment together, or offering prescriptions without a real exam.
• Advice to stop proven therapies or other medicines.
• Stories and testimonials instead of trial results.

To understand why most autism has many contributing causes, read what causes autism. For new studies as they appear, see our latest autism research roundup.

When to talk to a professional

Talk to your child’s doctor before starting leucovorin or any folate product. Seek help promptly if your child loses skills they once had, has seizures or unusual movements, or if their head growth seems to slow. If your child is already taking leucovorin, report new agitation, sleep problems, rashes or breathing trouble right away.

Frequently asked questions

Is leucovorin FDA-approved for autism?

No. In March 2026 the FDA approved Wellcovorin (leucovorin calcium) tablets for cerebral folate transport deficiency in people with a confirmed variant in the FOLR1 gene. That is a very rare genetic condition. The FDA said the evidence was not strong enough to approve leucovorin for autism in general, so any use for autism is off-label.

Does leucovorin help autistic children talk?

A few small trials reported gains in verbal communication, most notably a 2018 trial of 48 children. But studies are small and short, used different measures, and one of the larger trials was retracted in 2026 because its results could not be reproduced. We do not yet know which children, if any, benefit. Larger trials are under way.

What are the side effects of leucovorin in children?

In autism studies, side effects were usually mild. The most common were agitation or excitement, aggression, trouble sleeping, increased tantrums and headache. The AAP also lists stomach upset and irritability. Rarely, allergic reactions occur. Leucovorin can hide signs of vitamin B12 deficiency and may interact with some seizure medicines, so a doctor should monitor any child taking it.

Should I ask for an FRAA (FRAT) blood test?

Talk it through with your child’s doctor first. There is no FDA-cleared folate receptor antibody test, the tests are not standardized, and insurance may not pay. The AAP says results should not be used on their own to make treatment decisions. Doctors may instead consider genetic testing or a specialist referral if a child has signs that suggest a folate problem.

Can I buy folinic acid online instead?

We recommend against it. Leucovorin is a prescription medicine for good reasons: it can affect behavior, interact with seizure medicines and mask B12 deficiency. Supplements sold online are not reviewed by the FDA before sale, so strength and purity can vary. If you are curious about leucovorin for autism, start with your child’s doctor.

Learn how we research and review our articles on our how we check page, and read our medical disclaimer.

References

1. US Food and Drug Administration. FDA Takes Action to Make a Treatment Available for Autism Symptoms. News release, September 22, 2025. Link
2. US Department of Health and Human Services. President Trump, Secretary Kennedy Announce Bold Actions to Tackle Autism Epidemic. Press release, September 22, 2025. Link
3. US Food and Drug Administration. FDA Approves First Treatment for Patients with Cerebral Folate Transport Deficiency. News release, March 10, 2026. Link
4. GlaxoSmithKline / US Food and Drug Administration. WELLCOVORIN (leucovorin calcium) tablets: Highlights of Prescribing Information. NDA 018342/S-015, 2026. Link
5. National Cancer Institute. Leucovorin Calcium. Updated September 6, 2023. Link
6. American Academy of Pediatrics. Use of Leucovorin in Autistic Pediatric Patients: Interim Guidance. Updated October 31, 2025. Link
7. American Academy of Pediatrics. Leucovorin: Frequently Asked Questions for Pediatricians and Other Prescribing Pediatric Clinicians. Updated February 13, 2026. Link
8. Frye RE, Slattery J, Delhey L, et al. Folinic acid improves verbal communication in children with autism and language impairment: a randomized double-blind placebo-controlled trial. Molecular Psychiatry. 2018;23(2):247-256. Link
9. Renard E, Leheup B, Guéant-Rodriguez RM, Oussalah A, Quadros EV, Guéant JL. Folinic acid improves the score of Autism in the EFFET placebo-controlled randomized trial. Biochimie. 2020;173:57-61. Link
10. Batebi N, Moghaddam HS, Hasanzadeh A, Fakour Y, Mohammadi MR, Akhondzadeh S. Folinic Acid as Adjunctive Therapy in Treatment of Inappropriate Speech in Children with Autism: A Double-Blind and Placebo-Controlled Randomized Trial. Child Psychiatry and Human Development. 2021;52(5):928-938. Link
11. Panda PK, Sharawat IK, Saha S, Gupta D, Palayullakandi A, Meena K. Retraction Note: Efficacy of oral folinic acid supplementation in children with autism spectrum disorder: a randomized double-blind, placebo-controlled trial. European Journal of Pediatrics. 2026;185:109. (Retracts Eur J Pediatr. 2024;183:4827-4835.) Link
12. Society for Developmental and Behavioral Pediatrics. SDBP Affirms Commitment to Evidence-Based Care Following Retraction of Leucovorin Autism Study. January 30, 2026. Link
13. Rossignol DA, Frye RE. Cerebral Folate Deficiency, Folate Receptor Alpha Autoantibodies and Leucovorin (Folinic Acid) Treatment in Autism Spectrum Disorders: A Systematic Review and Meta-Analysis. Journal of Personalized Medicine. 2021;11(11):1141. Link
14. Zhang C, Chen Y, Hou F, et al. Safety and Efficacy of High-Dose Folinic Acid in Children with Autism: The Impact of Folate Metabolism Gene Polymorphisms. Nutrients. 2025;17(9):1602. Link
15. Ramaekers VT, Rothenberg SP, Sequeira JM, et al. Autoantibodies to folate receptors in the cerebral folate deficiency syndrome. New England Journal of Medicine. 2005;352(19):1985-1991. Link
16. Steinfeld R, Grapp M, Kraetzner R, et al. Folate receptor alpha defect causes cerebral folate transport deficiency: a treatable neurodegenerative disorder associated with disturbed myelin metabolism. American Journal of Human Genetics. 2009;85(3):354-363. Link
17. Society for Developmental and Behavioral Pediatrics. A Statement from the Society for Developmental and Behavioral Pediatrics on Recent Autism Claims. 2025 (undated PDF). Link
18. American College of Medical Toxicology. ACMT Position Statement: Use of Leucovorin for Autism Spectrum Disorder. Approved July 2026. Link
19. NIH Office of Dietary Supplements. Folate: Fact Sheet for Health Professionals. Link
20. Rothman JM, Kwan B, Longhurst CA, Jena AB. Rates of Leucovorin Prescriptions for Children With Autism. JAMA Network Open. 2026;9(5):e2613286. Link
21. Anuroj K. Cerebral folate deficiency, developmental difficulties in autism spectrum disorder and the role of leucovorin: a narrative review of mechanisms and clinical evidence. Drugs in Context. 2026;15. Link
22. Holle LM, Kratz J, Dow-Hillgartner EN, et al. HopeFOL, or FOL of problems? Leucovorin for autistic symptoms. The Oncologist. 2026;31(9):oyag304. Link
23. ClinicalTrials.gov. Folinic Acid as a Treatment for Autism Spectrum Disorder in Children (NCT07630506), KK Women’s and Children’s Hospital, Singapore. Link
24. ClinicalTrials.gov. A Placebo-controlled Trial of Folinic Acid in Children With ASD (NCT07642661). Link
25. Associated Press. FDA finds little evidence that the generic drug leucovorin can help people with autism. PBS News. March 10, 2026. Link
26. US Food and Drug Administration. Dietary Supplements. Link

Professional review: this guide is waiting for review by a qualified clinician. It was written and checked against the published sources listed above. How we check our guides.

This guide is general education, not medical advice. Always talk to your child’s doctor or care team. Last checked: October 2026.