Tylenol and Autism: A Quick Take on Why the Science Doesn’t Match the Headlines
The Trump administration’s claim alarms expecting mothers—but decades of research show no proof that acetaminophen causes autism. What matters: fever, dose, genetics, and context.
The Claim
The Trump administration recently asserted that acetaminophen (Tylenol) use during pregnancy leads to autism. It’s a striking claim, especially for pregnant women navigating many decisions. In my research for PHARMA, I’ve read hundreds of drug-safety and adverse effect studies. After reviewing the ones cited by the administration, I can say this unequivocally: there is no concrete scientific proof that Tylenol during pregnancy causes autism.
What We Know: Fever Itself Is Risky
One reason this matters: fever during pregnancy isn’t harmless. Multiple studies and clinical guidelines warn that maternal fever—especially recurrent or high fevers in early trimesters—has been associated with risks to neurodevelopment, including neural tube defects and other birth defects.
Untreated pain or fever can destabilize maternal physiology and negatively affect fetal well-being.
Treatment Choices: Why Tylenol Often Remains the Option
After around 20 weeks, the FDA discourages use of NSAIDs like ibuprofen/Advil/Motrin because of risks such as fetal kidney issues and low amniotic fluid when used in late pregnancy. U.S. Food and Drug Administration
Beyond that, NSAIDs can also be linked to heart, ductus arteriosus or other fetal complications in the third trimester.
That leaves acetaminophen as the safer over-the-counter option in many obstetric practice guidelines.
The American College of Obstetricians and Gynecologists has issued a statement warning that the suggestion that acetaminophen causes autism is irresponsible, noting that in over two decades of data, no high-quality study has shown a causal relationship. Still, Tylenol’s manufacturer (Kenzie) had made a social media post in 2017 that said, “We recommend pregnant women do not take any over-the-counter medication, including acetaminophen, without talking to their doctor first.”
That’s the advice from the lawyers. What about the science?
What the Studies Show (and Don’t)
A large Swedish cohort study of ~2.48 million children examined acetaminophen use in pregnancy and later risk of autism, ADHD, and intellectual disability. In standard models, a slight increase in risk was seen (HR ~1.05 for autism), but in sibling-matched analyses (controlling for family confounders), no link emerged (HR ~0.98) for autism, ADHD, or intellectual disability.
Observational studies and reviews (e.g. Prada et al. 2025, using the “Navigation Guide” methodology) present associations between prenatal acetaminophen exposure and neurodevelopmental disorders (NDDs) including autism—but they emphasize the methodological limitations, possible confounding, bias, and inability to prove causation.
A recent Mount Sinai study applying rigorous review methods suggests that higher-quality studies are more likely to find associations, but still cannot conclude any constitute proof.
Reviews in major science outlets caution that strong evidence of a causal link is lacking, even if the issue requires further study.
Autism diagnoses are up. Remember, that in part is due to an ever expanding definition of the “autistic spectrum.”
The Gap & My View
No study today shows a definitive causal pathway linking Tylenol in pregnancy to autism. The Trump administration is right that more and better studies are needed.
But many studies do not reliably control for confounding variables (fever, infection, maternal genetic predisposition, socioeconomic factors).
Fetal livers are immature, and metabolism differs in pregnancy—meaning standard adult dosing is not optimal.
My non-medical opinion based on the literature: “less is more.” If acetaminophen must be used, it would make sense to take the lowest effective dose, for the shortest duration possible (double check always with your OB/GYN)
Other Risk Factors: Genes, Timing, Brain Changes
Genetics play a major role in autism risk; environmental exposures likely interact with predispositions.
Neuroimaging work shows brain changes very early in pregnancy—or even before conception—suggesting causative processes likely begin before later exposures.
Any observed associations with acetaminophen may possibly reflect underlying maternal conditions, illnesses, or genetic predispositions, rather than direct causation.
Bottom Line
There is no solid proof that Tylenol use in pregnancy causes autism.
Fever itself is dangerous to pregnant women and fetuses and often needs treatment.
After ~20 weeks, avoid NSAIDs when possible due to known fetal risks.
Use acetaminophen only when needed, at the lowest effective dose and as briefly as possible.
Recognize the difference: correlation does not result in causation—and treat media claims with sensational headlines with healthy skepticism.
Maybe one day a study will establish conclusively a link between acetaminophen and neurodivergent conditions such as autism or ADHD. But the solid evidence is not yet available.
Postscript
In my book Pharma, I covered in detail the claims about whether vaccines caused autism. That also fell short of proof although the conclusions of a link from the original study had drawn worldwide headlines. The problem was that the study was fundamentally flawed: a dozen children directed to the study, and some of the funding for it, came from lawyers acting for parents who were involved in lawsuits against vaccine manufacturers.
And finally, history fans might be interested to know that it was the German drug giant, Bayer, who discovered acetaminophen. It was one of 4 groundbreaking drugs a Bayer team found over a 5-year span. Acetaminophen was the first, in 1897. Then the following year the Bayer team discovered Aspirin and Heroin (the latter named after the German word for ‘heroic’). In 1903, Bayer developed the first barbiturate, Phenobarbital. The only drug it did not release for sale to the public was acetaminophen, because it had mistakenly found it unsafe in its lab tests.
Not only "just the facts" that we needed at this time, but also explained in a way that us 'mere mortals' can understand! Thank you!
Gerald, thank you for the fact-based clarity offered on this important topic. It’s easy to shorthand the findings and draw spurious or erroneous conclusions. Your clear-eyed outlook and reporting are much in need and greatly appreciated.