Acetaminophen | Spectacle of blame

Every political story needs a villain and a vehicle. In the latest ‘Make America Healthy Again’ edition, the vehicle is maternal behaviour: what pregnant mothers take, what they eat, what they fail to suspect. In a previous era, they were blamed for overlooking vaccines; now they are being blamed for taking acetaminophen, aka paracetamol, during their pregnancy. But between the vaccine and paracetamol narratives, the strategy has been to reframe autism as a preventable harm caused by bad choices, and to marginalise social determinants and advances in genetics and leave mothers to carry the blame.

Acetaminophen has, of course, been made the villain. For a century now, this drug has been kept near bassinets and on bedside tables, and has been trusted to deal with fever and ordinary pain when stronger versions of other drugs would have been reckless. Pharmacology texts say it blunts prostaglandin signalling in the central nervous system and nudges receptors that modulate pain. While this picture remains incomplete and the subject of ongoing research, acetaminophen has been reliable in its effects against pain and temperature. Both researchers and regulators have said for many years that in excess, acetaminophen can also maim the liver.

In the new script, fronted by U.S. President Donald Trump and his health secretary Robert F. Kennedy Jr., acetaminophen has been dragged from outside the culture wars to a podium and asked to confess to something that can’t possibly be proven: that it “causes” autism when used during pregnancy. Scientists and obstetric groups have already objected to this accusation. The World Health Organization has publicly repudiated it.

Some observational studies, but especially an analysis published in JAMA Psychiatry in 2019, reported that higher in-utero levels were statistically associated with later diagnoses such as autism. A consensus statement in Nature Reviews Endocrinology in 2021 urged a “precautionary” approach to the drug.

However, these and some other papers set out associations, not proof of causation, and admitted to being vulnerable to confounding by the very illnesses acetaminophen treats (including fevers), by genetics, and by family environment.

Rhetorical effect

However, the Trump-RFK combine has mutated “might be associated under certain conditions” into “is a primary cause”. The rhetorical effect has been to pin responsibility not on access to care and diagnostics and environmental exposure but on imputed maternal failings. But just as vaccines don’t cause autism — epidemiology and reviews have repeatedly proved this — professional bodies have maintained that acetaminophen is appropriate during pregnancy when medically indicated and at the lowest effective dose.

Indeed, in 2024, a large Swedish population study reported that the small increases in risk observed in simpler studies disappeared when matched siblings were analysed. Its findings were a powerful rebuttal to lazy causal claims. Courts have also had their say: one federal judge excluded plaintiffs’ experts in a multidistrict litigation and dismissed hundreds of cases, finding their methods unreliable. Only political theatre is breathing new life back into these claims.

Acetaminophen also has its own baggage and it would be dishonest to omit it. It’s the leading cause of acute liver failure in the U.S. Everyone who prescribes it is expected to be aware of the dosage ceiling as well as be mindful of the fact that certain combinations with other drugs can render it poisonous.

Ultimately, acetaminophen is a tool — and a sobering one at that. It returns the drug to the clinic, where decisions are individualised and the risks are explicit. It returns autism to being a spectrum of neurodevelopmental differences with a complicated matrix of causes, rather than a punishment for taking a pill during a difficult pregnancy. And ultimately, it returns public health to its first principles: that one shouldn’t claim causal links sans evidence, shouldn’t trade in fear where counsel is required, and shouldn’t allow the spectacle of blame to substitute for the work of care.