Autism is not caused by Tylenol. That blunt fact emerges from the largest inquiry yet into the supposed link. Last year Swedish researchers, led by Viktor H. Ahlqvist, published in JAMA the results of a study following 2.48m births between 1995 and 2019. By matching prescription and exposure records with later diagnoses of autism, ADHD and intellectual disability, they found no evidence of a causal connection.
The conclusion was stark. Across the breadth of Sweden’s population, there appeared at first to be a weak correlation: mothers who took paracetamol during pregnancy seemed slightly more likely to have children later diagnosed with autism, ADHD, or intellectual disability. But that shadow of a link dissolved under closer scrutiny. When researchers examined siblings within the same family—one exposed to paracetamol in the womb, the other not—the pattern vanished.
The authors put it plainly: “After accounting for familial confounding using sibling comparisons, acetaminophen use during pregnancy was not associated with increased risks of autism spectrum disorder, attention-deficit/hyperactivity disorder, or intellectual disability.”
What looked like evidence of harm was nothing more than statistical noise, explained by genetics and environment shared between siblings. This study, massive in scope and rigorous in design, cuts through years of speculation. It is, in effect, the most methodical dismantling yet of a myth that has haunted American medicine—proof that what so many feared was never there at all.
That’s the truth.
Sweden's sharp scalpal
The Swedish study matters because of its scale, its methods and its setting. Sweden’s national health registers are among the best in the world, covering virtually the entire population, prospectively and in detail. That allows scientists to link prescriptions, pregnancy records and child outcomes with remarkable precision. The design also offered an extraordinary tool: the sibling comparison. By holding constant parental genetics and family environment, the study stripped away the noise that bedevils observational medicine. What remained was nothing.
Across 2.48m births, including more than 185,000 pregnancies where mothers reported acetaminophen use, the risk ratios for autism, ADHD and intellectual disability in sibling analyses hovered around one—meaning no association. In effect, the apparent danger seen in cruder population models was not caused by the drug at all but by the families who happened to use it.
This is not just another footnote in epidemiology. It is a rebuke to the many voices that have trafficked in fear and confusion about Tylenol, sowing mistrust of basic medicine.
American addiction to alarm
In America, acetaminophen has long been a punching bag for conspiracy entrepreneurs. Once whispers of a link between prenatal Tylenol and autism appeared in a handful of small observational studies, the cottage industry of pseudoscience moved swiftly. Lawyers scented class actions. Grifters filled YouTube channels with dire warnings. Facebook groups metastasised with tales of damage supposedly wrought by a cheap, over-the-counter painkiller.
The myth took hold because it fit a pattern. Vaccines had already been falsely accused of causing autism. Paracetamol, so common and so banal, offered the next scapegoat. Each new paper, no matter how limited, was paraded as proof. That these studies were riddled with bias and confounding did not matter. The story was too good, too lucrative, too politically useful.
The Swedish result leaves those claims in ruins. It shows that what looked like harm was in fact the product of background factors—maternal health, genetics, family environment—that predispose both to paracetamol use and to developmental risk. In other words, it was never the medicine. It was the messiness of human life.
The cost of incompetetence
If the problem stopped with internet cranks, the story might end here. But the more harmful damage came when elements of the American state lend credibility to the panic. Worse still when the President weaponise the lies.
This is wilful blindness masquerading as caution. Ordinary Americans, bombarded by claims of danger, are left to wonder whether a standard headache tablet could ruin their child’s future. Some women may skip treatment for fever or pain during pregnancy, not realising that untreated maternal illness can itself threaten a fetus.
Public health is not only about science but about trust. When governments fail to correct falsehoods, they allow corrosive stories to spread.
What's happening in America today is much worse. It is deliberate malfeascence.
The cost is measured not just in anxiety but in lives disrupted by untreated illness.
The Swedish researchers did not stumble on their result by chance. They designed their study to address precisely the weaknesses of earlier work. Prior studies, often based on parental recall, were vulnerable to misreporting. Many were too small to yield reliable answers. Almost all failed to account for the shared family factors that confound observational research.
By drawing on registers covering nearly 25 years, and by exploiting sibling comparisons, the Ahlqvist team sidestepped these traps. Their method was not flashy; it was rigorous. That is the quiet power of well-designed epidemiology: it can cut through noise that entire legal and media industries have amplified.
The lesson should be obvious. Science advances not by cherry-picking associations but by asking whether those associations survive serious attempts to falsify them. In this case, they did not.
The broader disease
What does this tell us about American health politics? That the real contagion is not autism but credulity. Each time a false scare gains traction, the pattern repeats: a small observational finding, inflated into a headline, then weaponised by lawyers and opportunists. Citizens lose faith in medicine.
This cycle is not harmless. It corrodes confidence in vaccines, in pain relief, in the very idea that science can answer questions of safety. It drains energy from genuine research into the causes of autism, which remain complex and poorly understood. And it distracts from the practical steps, early diagnosis, tailored education, family support, that could make life better for those affected.
The Tylenol myth is just one episode in a longer saga of medical misinformation. But it is instructive. Here is a case where extraordinary data, drawn from an entire nation, delivers clarity. It should have been greeted with relief, even celebration.
Instead, America panders to conspiracy theories, and to the ego of a Health Secretary whose brain was chewed by a worm.
Armed with the facts
There are all kinds of practical steps that could follow from this study. First, regulators could say clearly that paracetamol in pregnancy is safe when used as directed. Second, courts could recognise that class-action litigation built on phantom science is itself harmful, diverting attention and resources from real public health needs. Third, politicians could learn to confront nonsense quickly.
Or Amercia decided, we could ignore the evidence and ban Tylenol. Yeah, let's do that.
Critics may say that caution is prudent, that medicine is littered with once-safe drugs later found to cause harm. True enough. But prudence is not the same as paralysis. To stand mute while grifters peddle falsehoods is not prudence. It is incompetence. Worse, it is reckless. The refusal to confront misinformation allows it to harden into belief, which is harder to reverse than it is to prevent.
The comparison with Europe is instructive. There, regulators acknowledged the questions but placed them in proportion, insisting on evidence before alarm. The result: less litigation, less hysteria, more trust. America, by contrast, has exported its culture of suspicion, damaging confidence in safe drugs around the world.
The stakes
Why does this matter? Because every scare has knock-on effects. If mothers doubt paracetamol, what next? Doubts about antibiotics? About obstetric anaesthesia? About vaccines? Once mistrust takes root, the consequences are broad. The harm is cumulative.
And the harm is political, too. Each false alarm fuels the narrative that elites cannot be trusted, that science is a racket, that experts are corrupt. This narrative is then harnessed by populists who thrive on chaos. Thus a mistaken belief about a household painkiller morphs into a weapon in the wider war on reason.
The Ahlqvist study should be read not only as a medical paper but as a public document. It speaks with clarity at a time when clarity is rare. It restores proportion to a debate warped by speculation. And it demonstrates the power of good science, properly designed and patiently executed, to answer questions that gossip and litigation cannot.
Autism is not caused by Tylenol. That is the headline. Everything else is noise.
The disease Americans should be most concerned about is the contagion of stupidity spreading across the body politic.