A White House briefing that made unsubstantiated medical claims about two medications — without new clinical evidence and bypassing the FDA's standard review process — has left a measurable trail of altered prescribing patterns across the United States. The damage includes a dangerous drop in a pregnancy-safe painkiller and an explosive surge in an unapproved autism drug whose largest supporting clinical trial was subsequently retracted. Two peer-reviewed studies, the most comprehensive published in JAMA Network Open on May 18, 2026, have now quantified that damage in national electronic health record data covering more than 300 million patients.
What Officials Claimed at the September 22 Briefing
On September 22, 2025, President Trump, Health and Human Services Secretary Robert F. Kennedy Jr., FDA Commissioner Marty Makary, and other federal officials held a White House briefing on autism. During the event, Trump warned pregnant women to limit their use of acetaminophen — the active ingredient in Tylenol — claiming it was linked to autism in children. Kennedy called leucovorin, a drug primarily used to counteract the toxic side effects of chemotherapy, "an exciting therapy that may benefit large numbers of children who suffer from autism."
Neither claim was supported by new clinical evidence, and neither followed the FDA's standard regulatory process for updating drug guidance — a process that normally involves peer review, public input, and transparent scientific evaluation.
The best available evidence on the acetaminophen question ran firmly in the opposite direction. A 2024 sibling-controlled cohort study published in JAMA, which analyzed 2.48 million children born in Sweden between 1995 and 2019, found no increased risk of autism, ADHD, or intellectual disability when sibling pairs with and without prenatal acetaminophen exposure were directly compared — the strongest methodological design available for controlling genetic and environmental confounding.
Leucovorin Prescriptions for Autistic Children Jumped 2,000%
The UC San Diego study, published May 18, 2026 in JAMA Network Open, analyzed Epic Cosmos electronic health record data covering more than 300 million patient records from over 1,800 hospitals and 41,500 clinics across all 50 states. It tracked leucovorin prescription rates for 838,801 children with autism over 11.9 million outpatient encounters between January 2023 and January 2026.
For roughly two years, prescribing held steady at about 34 prescriptions per 100,000 outpatient encounters. The first detectable rise began in February 2025, coinciding with a CBS Evening News segment featuring a family who reported dramatic language improvements in their autistic child after starting leucovorin. By August 2025, prescribing had risen to 335 per 100,000 encounters. After the September 22 White House briefing, it climbed further to more than 835 per 100,000 encounters in November 2025 — an increase of more than 2,000% above the two-year baseline.
"Families of children with autism are often searching for therapies that might improve communication and quality of life, especially when treatment options are limited," said lead author Joshua Rothman, MD, a clinical assistant professor of pediatrics at UC San Diego School of Medicine. "What this study shows is how quickly information shared through news coverage, social media, and public figures can influence real-world prescribing patterns, even before large clinical trials establish whether a treatment is truly safe and effective."
Acetaminophen Orders Among Pregnant Patients Fell 10%
A companion study published in The Lancet in March 2026, by researchers at Harvard Medical School's emergency medicine division and Brown University's School of Public Health, analyzed prescribing changes in a separate national Epic dataset covering 88,857 emergency department visits by pregnant patients and 853,216 visits by non-pregnant patients between September 22 and December 7, 2025.
The findings were stark. Acetaminophen orders for pregnant women in emergency rooms dropped by 10% compared with expected rates — with the initial-month decline reaching 16% and a low point of 20% below expected levels in the third week after the briefing. No equivalent change was seen among non-pregnant women, confirming the effect was targeted specifically at expectant mothers.
Acetaminophen is one of the only pain and fever medications clinically recommended for use during pregnancy, according to the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine. Untreated fever and pain during pregnancy carry documented risks for both mother and fetus. "The results show just how much political leaders can steer health behavior even when there has been no change in the evidence for these therapies," said Dr. Michael Barnett, a co-author of the Lancet study and a professor of health services, policy and practice at Brown University.
How Leucovorin Works — and Why It Cannot Treat Most Autism
Leucovorin is a biologically active reduced form of folic acid, also known as folinic acid. Unlike standard folic acid, leucovorin can cross the blood-brain barrier via an alternate pathway called the reduced folate carrier (RFC), in addition to the standard folate receptor alpha (FRα). In cerebral folate deficiency, the FRα receptor is blocked or absent due to a specific gene mutation, and leucovorin's ability to use the RFC pathway is precisely what makes it effective for that specific condition.
The FDA formally approved leucovorin on March 10, 2026 — but only for cerebral folate deficiency in patients with a confirmed variant in the FOLR1 gene, a condition affecting fewer than one in a million people. The FDA explicitly declined to endorse leucovorin for autism spectrum disorder broadly, because the molecular mechanism that makes it effective for FOLR1-variant patients does not apply to children with autism who do not have this specific genetic defect. There is no established evidence that most autistic children have impaired FRα transport.
American Academy of Pediatrics Does Not Recommend Leucovorin for Autism
The American Academy of Pediatrics published interim guidance in late 2025 stating it does not recommend leucovorin for autism spectrum disorder. The AAP noted that existing evidence is limited to small studies, mostly in children who have specific folate metabolic differences, and that effects can be "positive, neutral, or negative, depending on an individual child's biology." According to the AAP, the 2,000%+ surge meant clinicians were prescribing leucovorin at a rate far outpacing any coherent clinical rationale.
Several small randomized controlled trials had suggested that a subset of autistic children with folate receptor autoantibodies might show some communication improvements on leucovorin. But that narrow evidence base became even narrower on January 29, 2026.
Largest Clinical Trial Supporting Leucovorin for Autism Was Retracted
The largest randomized controlled trial of leucovorin in autistic children — a study by Panda and colleagues, originally published in the European Journal of Pediatrics in September 2024 and enrolling 77 children — was formally retracted by the journal on January 29, 2026, citing data inconsistencies and statistical errors that a post-publication review could not reconcile.
"The retraction of this paper removes a significant portion of the already weak evidence supporting the value of folinic acid as a treatment for autism," Thomas Challman, a pediatric neurodevelopmental specialist at Geisinger College of Health Sciences, said in a statement at the time. "Until we have acceptable evidence of safety and effectiveness, folinic acid use as a treatment for autism is not appropriate outside of a well-designed clinical trial."
The retraction meant that by the time the UC San Diego prescribing surge data was published in May 2026, the 2,000%+ rise in off-label leucovorin prescribing had occurred nearly entirely on the basis of evidence that had since been formally invalidated. The surge also created immediate harm for a different group of patients: children with confirmed FOLR1-variant cerebral folate deficiency — the only population for whom the drug is both approved and effective — reported difficulty finding leucovorin due to supply shortages driven by autism-related demand.
What Researchers Are Calling For
"An important implication of these results is also that it's not just patients who were influenced by the unconventional press conference," Barnett said. "Their doctors were either influenced themselves or pushed by patients to adopt a new practice." He described the leucovorin surge as "a bit of a failure of the medical system."
Both research teams called for action on parallel tracks. The UC San Diego group urged larger, well-designed randomized trials to evaluate whether leucovorin benefits specific subpopulations of children with autism — particularly those with documented folate autoantibody abnormalities — before off-label prescribing continues at current scale. The Harvard and Brown team called for tighter standards governing how federal health communications are developed, noting that the September 22 briefing bypassed every procedural safeguard that normally governs changes to drug guidance.
A third study published in Pediatrics this week by researchers at Harvard's Program On Regulation, Therapeutics, and Law corroborated both the leucovorin surge finding and its connection to the September briefing, adding further weight to the evidence that federal messaging drove the prescribing shift without clinical justification.
For pregnant patients specifically: acetaminophen remains the analgesic and antipyretic of choice during pregnancy, according to both ACOG and the Society for Maternal-Fetal Medicine, and avoiding it when clinically warranted carries real risk.
Frequently Asked Questions
Is leucovorin an approved treatment for autism?
No. As of June 2026, leucovorin is not FDA-approved for autism spectrum disorder. The FDA approved leucovorin in March 2026 for a specific ultra-rare genetic condition — cerebral folate transport deficiency caused by a confirmed FOLR1 gene variant — that affects fewer than one in a million people. The FDA declined to endorse leucovorin for the broader autism population after reviewing the available evidence and finding it insufficient.
Is acetaminophen safe to take during pregnancy?
Yes, according to the leading obstetric organizations. The American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine both continue to recommend acetaminophen as the first-line pain and fever medication for pregnant patients. The most rigorous study on the subject — a 2024 Swedish sibling-controlled cohort of 2.48 million children — found no causal link between prenatal acetaminophen use and autism, ADHD, or intellectual disability.
What happened to off-label autism drug prescriptions after the White House briefing?
Following the September 22, 2025 briefing, leucovorin prescriptions for children with autism rose more than 2,000% above baseline levels by November 2025, tracking a CBS News segment from February 2025 and then accelerating sharply after the federal announcement. At the same time, acetaminophen orders in hospital emergency departments for pregnant women fell roughly 10%, with an initial low of 20% below expected levels in the third week — despite no change in clinical guidelines or new clinical trial evidence.
How does leucovorin work, and why does it matter for autism?
Leucovorin crosses the blood-brain barrier via the reduced folate carrier pathway, bypassing the folate receptor alpha that standard folic acid depends on. This makes it an effective treatment when that receptor is absent due to the FOLR1 gene mutation. Whether children with autism who do not have this specific mutation benefit from leucovorin is unresolved — the question is the subject of ongoing research, and the largest clinical trial examining it was retracted in January 2026 due to data errors.
This article is based on peer-reviewed research. TechTimes does not provide medical advice. Readers should consult a qualified clinician before making any changes to their medication regimen.
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