Decades of research, including large-scale studies published in JAMA and statements from the NIH, have consistently found no causal connection.
By Matthew A. McIntosh
Public Historian
Brewminate
Introduction
Donald Trump and Robert F. Kennedy, Jr., are now claiming that acetaminophen, the active ingredient in Tylenol and one of the most commonly used pain relievers in the world, causes autism when taken during pregnancy. The assertion, delivered with political bravado, has already ricocheted across headlines and social media. But there’s a glaring problem: the science simply doesn’t back up the pseudoscience they spewed.
Autism was identified and studied decades before acetaminophen became widely available in the 1950s, and careful research has repeatedly shown no causal link between prenatal use of the drug and autism diagnoses. Large-scale studies, including one published this year in JAMA, found that once genetic and environmental factors were accounted for, the association essentially disappeared. The NIH and the Cleveland Clinic have gone further, stating flatly that the evidence does not support a causal connection.
So why advance the claim anyway? For Trump and Kennedy, it plays into a familiar strategy: sowing doubt about mainstream medicine while presenting themselves as truth-tellers willing to challenge “the establishment.” It’s a tactic with political payoff, even if it comes at the expense of public health. And the danger is real: exaggerated warnings can leave pregnant people confused, frightened, and unwilling to treat fevers and pain, conditions that themselves can endanger a developing fetus.
Background: The Claim and Political Context
They unveiled their latest claim in a joint announcement that framed acetaminophen as a hidden culprit behind rising autism diagnoses. The message was clear: mainstream medicine has been ignoring the “real” cause, and only they were bold enough to call it out. It was delivered with the same mix of alarm and certainty that has long fueled vaccine skepticism and conspiracy-driven health narratives.
The timing wasn’t accidental. Autism has become a political flashpoint, with communities still scarred by decades of misinformation linking vaccines to developmental disorders. By shifting the blame to a drug as common as Tylenol, they tapped into a familiar pattern: targeting something widely used, raising fear, and positioning themselves as the only leaders willing to “tell the truth.”
But the science doesn’t support them. Research into autism stretches back to the early 20th century, long before acetaminophen was even approved for over-the-counter sale. Its prevalence has risen largely because of expanded diagnostic criteria, better awareness, and improved screening, not because of a single household medicine. Casting acetaminophen as the new villain may play well politically, but it distorts decades of evidence and risks frightening millions of pregnant women without cause.
What the Best Scientific Evidence Says
Decades of research have tested the question Trump and Kennedy now claim to have answered, and the evidence is clear: acetaminophen use during pregnancy does not cause autism.
A massive sibling-control study published in JAMA this year found no increased risk once genetics and shared family environment were factored in. This method matters because it strips away many of the confounding variables (like parental mental health, socioeconomic factors, or environmental exposures) that could otherwise skew results.
The National Institutes of Health reinforced these findings in its own release, stating bluntly that no causal link exists between acetaminophen use before birth and neurodevelopmental disorders. The Cleveland Clinic reached the same conclusion in a separate review, emphasizing that families should not fear the medication when it’s used as directed.
Even studies that have suggested a possible connection, such as those relying on self-reported usage, have been criticized for serious methodological flaws. As the PBS NewsHour reported, those studies often fail to distinguish whether it was the drug itself or the underlying condition, such as fever or infection, that carried risk. When better controls are applied, the supposed link collapses.
The bottom line: the most rigorous evidence available shows no causal relationship. Claims to the contrary may generate headlines, but they are not grounded in science.
Why Confounding & Methodology Matter
Part of the reason the acetaminophen–autism claim refuses to die is that some early observational studies hinted at an association. But association is not causation, and those findings don’t hold up under stricter analysis.
One major issue is confounding. Pregnant women often take acetaminophen for fevers, infections, or chronic pain, conditions that themselves may affect fetal development. If you don’t separate the effect of the illness from the effect of the drug, it’s easy to misinterpret the results. That’s why more rigorous designs, like the JAMA sibling study, are crucial: they compare outcomes within families, controlling for genetics and shared environment.
Another problem is self-reporting. Many studies relied on pregnant women recalling how much acetaminophen they used, and when. This is prone to error and exaggeration, especially years later when autism diagnoses come into play. As the NIH noted, such data can suggest patterns, but it can’t prove causation.
Even dose and timing are rarely measured with precision. Occasional use for headaches or fevers is lumped together with long-term, high-frequency use. Without clear dosage data, the conclusions are shaky at best. In short, weak study design creates noise that conspiracy-minded politicians are only too eager to amplify.
Reaction from the Medical and Scientific Community
Medical experts moved quickly to push back against the claim, warning that it risks creating unnecessary fear among pregnant women. The American College of Obstetricians and Gynecologists reaffirmed that acetaminophen remains the safest pain reliever during pregnancy when used as directed. They stressed that untreated fever, pain, or infection can pose far greater risks to both mother and fetus than the medication itself.
International health agencies echoed that stance. The European Medicines Agency reiterated that paracetamol, the name for acetaminophen in Europe, is safe for use in pregnancy, rejecting any suggestion that it causes autism. The World Health Organization has issued similar guidance, emphasizing that no evidence supports a causal link.
Clinicians also raised concerns about the collateral damage of such rhetoric. As NBC News reported, overstated warnings could scare pregnant people away from using the only safe fever reducer available to them. High fever during pregnancy is a known risk factor for developmental complications, meaning the “cure” of avoiding acetaminophen could do more harm than the medicine itself.
The consensus is clear: acetaminophen has been used safely for decades, and the scientific evidence does not support their claim. What worries doctors most is not the medicine; it’s the misinformation.
Risks of Making Overstated Claims
The danger of this crazy claim isn’t abstract. When national figures suggest that a common medication causes autism, it creates confusion and panic among those least equipped to parse scientific nuance. Pregnant people may avoid acetaminophen out of fear, leaving them without the safest treatment for fever or pain. As PBS NewsHour pointed out, untreated high fever in pregnancy can itself increase risks for complications, potentially doing far more harm than the drug ever could.
There’s also the psychological toll. Suggesting a link between Tylenol and autism fuels guilt and shame, making parents feel as though a routine painkiller could be to blame for their child’s diagnosis. That kind of messaging doesn’t just lack evidence; it stigmatizes families already navigating the challenges of autism.
And beyond individual households, overstated claims erode trust in health authorities. If people believe the government has been “hiding” the truth about acetaminophen, it feeds the same conspiracy ecosystem that has already undermined vaccines, masks, and other public health measures. Once trust is broken, rebuilding it is far harder, and misinformation tends to linger long after the science is clear.
What We Still Don’t Know and Research Needs
Science is rarely absolute, and researchers continue to study how medications interact with fetal development. But the nuance here matters: ongoing research is about refining understanding, not uncovering some hidden link that proves acetaminophen causes autism.
Experts agree that more rigorous, long-term studies would be useful, particularly those that can measure actual dosage and timing rather than relying on self-reported use. As the NIH noted, current evidence is limited by reliance on surveys and recall. More precise tracking would help rule out even small risks.
There’s also interest in better controlling for confounding factors like maternal infections, genetic predispositions, and environmental exposures, all of which can influence neurodevelopment. As the JAMA sibling study demonstrated, when you compare children within the same family, the supposed link disappears, suggesting other variables, not acetaminophen, are the real drivers.
Finally, researchers continue to call for biological plausibility: evidence of a mechanism by which acetaminophen could alter brain development. To date, no such mechanism has been demonstrated in humans. Without that, bold claims about causation remain scientifically hollow.
The upshot: science is still refining its picture, but the data we have today do not justify the sweeping claims made by Trump and Kennedy.
Conclusion
The claim that acetaminophen use in pregnancy causes autism is not supported by science. Decades of research, including large-scale studies published in JAMA and statements from the NIH, have consistently found no causal connection. Acetaminophen has been used safely for generations, and professional bodies like the American College of Obstetricians and Gynecologists continue to recommend it as the safest pain reliever during pregnancy.
What they are offering isn’t science; it’s politics. By framing Tylenol as a hidden culprit, they’re recycling the same tactics used to cast doubt on vaccines: fear, suspicion, and the false promise of a simple cause for complex conditions. The real cost is public confusion, unnecessary guilt for parents, and potential harm to pregnant people who may avoid the only safe fever reducer available to them. History has already shown what happens when conspiracy theories drive health policy: trust erodes, science takes a back seat, and vulnerable people pay the price. Autism is not caused by Tylenol. Pretending otherwise won’t advance science, but it will deepen the damage of misinformation.
Originally published by Brewminate, 09.24.2025, under the terms of a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International license.
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