Trump’s Tylenol Warning Led to Shifts in Painkiller & Autism Drug Use

“Don’t take Tylenol. Don’t take it.”

That stark warning, issued by former President Trump last year, reverberated through emergency departments and pharmacies, leading to a measurable shift in medication use among pregnant individuals, according to a new study published Thursday in The Lancet. The president’s claim – that using acetaminophen, the active ingredient in Tylenol, increased the risk of autism in children – despite a lack of scientific consensus, prompted a significant decrease in its use during pregnancy and a corresponding spike in prescriptions for leucovorin, a drug with limited evidence of effectiveness for autism.

A Rapid Response to Unsubstantiated Claims

The study, led by researchers at Brown University and Brigham and Women’s Hospital, analyzed electronic health records from nearly 90,000 emergency department visits involving pregnant individuals and over 850,000 visits from non-pregnant individuals. The findings reveal a 16% initial dip in acetaminophen orders in emergency departments following Trump’s September press conference, leveling off to a 10% decrease over the subsequent twelve weeks. Notably, no statistically significant change was observed in acetaminophen use among non-pregnant women. Simultaneously, outpatient prescriptions for leucovorin surged by 71% during the same period, equating to an increase of 17 prescriptions per 100,000 visits.

“This is an embodiment of how much power our federal health officials have,” explained Michael Barnett, a study author and professor at the Brown University School of Public Health. “Even when nothing in the evidence base has changed, even for something as ubiquitous and familiar as Tylenol, it can still shift things to a measurable degree within days.”

The Evidence – and Lack Thereof – Linking Acetaminophen and Autism

The former president’s assertion regarding a link between acetaminophen and autism stemmed from concerns about potential neurodevelopmental effects. Although, as Nature reported in September 2025, the scientific community largely cautions against drawing definitive conclusions. While acetaminophen is one of the most commonly used medications during pregnancy – utilized by roughly half of all pregnant people worldwide – the evidence linking it to autism remains inconclusive. Researchers emphasize that observed associations are, at best, very small and that focusing solely on acetaminophen risks diverting attention from other potential contributing factors to the rising prevalence of autism.

James Cusack, chief executive of Autistica, a UK-based autism research charity, and himself autistic, stated, “There is no definitive evidence to suggest that paracetamol use in mothers is a cause of autism, and when you see any associations, they are very, very small. At the heart of this is people trying to look for simple answers to complex problems.”

Beyond Acetaminophen: The Rise of Leucovorin

Alongside the warnings about acetaminophen, the Trump administration also promoted the use of leucovorin, a drug primarily used in cancer treatment. While some researchers, like Robert Hendren, have suggested leucovorin may have modest benefits for a subset of individuals with autism, research has tempered initial expectations. The 71% increase in leucovorin prescriptions following the administration’s public endorsement, however, reflects a significant shift in prescribing patterns, driven in part by its relatively small existing market.

The administration’s promotion of leucovorin took on the characteristics of a direct-to-consumer pharmaceutical advertisement, raising concerns among some experts.

Unanswered Questions and Potential Risks

The Lancet study highlights several critical gaps in our understanding. It doesn’t reveal whether the decrease in acetaminophen use was driven by clinicians or patients, nor does it account for changes in acetaminophen use outside of emergency department settings. Perhaps most concerningly, the study doesn’t indicate whether patients substituted acetaminophen with other pain relievers, some of which may pose greater risks during pregnancy.

Lisa Croen, director of the Kaiser Permanente Autism Research Program, emphasized this point: “Tylenol is the medication that is safe, the one medication that is safe to control pain and fever during pregnancy. We don’t grasp if people were substituting paracetamol for other pain meds that are known to be hazardous [during pregnancy], like ibuprofen.”

A Broader Context: Autism Research and Public Health Messaging

The Trump administration’s actions extended beyond medication recommendations. Officials also characterized the rising rates of autism diagnoses as an “epidemic,” a claim disputed by many researchers. The administration removed federal webpages providing information on the potential harms of controversial autism treatments and proposed a national autism registry that sparked fear and mistrust within the autism community.

Croen cautioned that making statements unsupported by rigorous scientific evidence is “very harmful to the U.S. Population, children and adults,” and necessitates ongoing efforts to re-educate the public about evidence-based practices.

What Comes Next: Continued Surveillance and Evaluation

The Department of Health and Human Services, under the current administration, has indicated it will not alter its approach to this issue, defending its messaging as “pro-patient” and committed to transparency regarding public health risks. However, ongoing surveillance of medication use patterns and autism diagnoses will be crucial to assess the long-term consequences of these policies. Further research is needed to determine whether the observed changes in acetaminophen and leucovorin use have any impact on autism rates or other health outcomes. Public health officials will also need to continue to address misinformation and promote evidence-based guidance to ensure informed decision-making among pregnant individuals and their healthcare providers.