Q&A: Acetaminophen-Autism Link Highlights Issues of Confounding Evidence

Since the COVID-19 pandemic, the role of scientific evidence in the greater health care community has been significantly distorted. From the public’s belief in myths about a variety of vaccines to misinformation surrounding reproductive health,¹ the Trump Administration’s recent call linking acetaminophen (Tylenol) use with autism spectrum disorder is the next event in the saga of conflicting scientific information.

“Generally speaking, people seem to be foggy on what ‘science’ is, in terms of ‘what does the science say?’ Should ‘science’ include every single publication, regardless of the business of journals?” asked Mark Garofoli, PharmD, BCGP, CPE, CTTS, clinical assistant professor at the West Virginia University School of Pharmacy and host of the Pharmacy Podcast Network’s Pain Pod. “There is a publication or 3 for every single point of view. It is not enough to say that one single study (or even a handful of small studies) makes something correct.”

To get insights from a pharmacist and medical professional with expertise on drugs like Tylenol, we caught up with Garofoli to get his thoughts on the circulation of scientific evidence regarding this monumental link between a major neurodevelopmental disorder and one of the most well-known over-the-counter medications.

Garofoli explored the referenced studies in the Trump Administration’s push to link acetaminophen use with autism. | image credit: Andy Dean / stock.adobe.com

From the studies that the administration has referenced to the overarching implications this link has on the health care and scientific communities, he helped us better understand the importance of questioning and scrutinizing scientific evidence.

READ MORE: Q&A: Pain Medication Expert on Controversy Surrounding Acetaminophen-Autism Link

Drug Topics: Have you had a chance to peruse the studies that link acetaminophen use with autism that the Trump Administration has been referencing? What are your opinions on those studies?

Mark Garofoli: It would be rather inappropriate for anyone to comment on a publication without having not only read the article yet also scrutinized its components. Although that is obvious, so many clinicians have been faced with strong contrary comments from folks who didn’t even read the article.

Before reviewing the review, let’s pause to consider one of the author’s comments when recently interviewed, ‘What we recommend is judicious use—the lowest effective dose [for] the shortest duration of time under medical guidance and supervision, tailored to the individual.’ Does that sound the same as what was conveyed to our American public? No.²

The largest study included in the respective review article involved 2.5 million Sweden babies born from 1995 to 2019 with follow up in 2021. Unlike previous studies, this study compared siblings within the same family to remove genetic and familial bias—and poof, the risk disappeared. In other words, acetaminophen [was] not guilty. Also of note, the authors’ conclusion was, ‘Acetaminophen use during pregnancy was not associated with children’s risk of autism, ADHD, or intellectual disability in sibling control analysis. This suggests that associations observed in other models may have been attributable to familial confounding.’ That is a powerful statement; a mic drop.³

A high percentage of the studies in the review article had statistical concerns including confidence intervals crossing ‘1.’ For the sake of conversation, that’s a no-no.

A 2021 European Journal of Epidemiology study involving about 74,000 children found a mild odds ratio of 1.2 for autism/ADHD symptoms (meaning 2 additional children out of every 100), however, that’s symptoms, not diagnoses, a major consideration.⁴

A 2019 JAMA Psychiatry biomarker study measured acetaminophen and metabolites in the cord plasma of almost 1000 newborns (relatively small sample size) after one exposure to acetaminophen for the mother and found a hazard ratio of 3.62 for autism in those with the highest levels but did not account for the original acetaminophen dosages and frequency. [It] very importantly did not account for familial nor genetic factors as was the case with many earlier studies.⁵

Generally speaking, people seem to be foggy on what ‘science’ is, in terms of ‘what does the science say.’ Should ‘science’ include every single publication, regardless of the business of journals? There is a publication or 3 for every single point of view. It is not enough to say that one single study (or even a handful of small studies) makes something correct. Or not at the time, rather, substantiated studies endorsed by reputable professional organizations can lead the way. One would think that the peer review process would accomplish this herculean task, yet we all know that is simply not the case. If I had a nickel for every time I asked myself, “How, or even why, was that published?”

READ MORE: Trump Administration Claims Link Between Autism and Acetaminophen Use in Pregnancy

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REFERENCES

1. Poll: Most Americans encounter health misinformation, and most aren’t sure whether it’s true or false. News Release. KFF. August 22, 2023. Accessed September 26, 2025. https://www.kff.org/covid-19/poll-most-americans-encounter-health-misinformation-and-most-arent-sure-whether-its-true-or-false/

2. Prada D, Ritz B, Bauer AZ, et al. Evaluation of the evidence on acetaminophen use and neurodevelopmental disorders using the Navigation Guide methodology. Environ Health. 2025 Aug 14;24(1):56. doi: 10.1186/s12940-025-01208-0.

3. Ahlqvist VH, Sjöqvist H, Dalman C, et al. Acetaminophen use during pregnancy and children’s risk of autism, ADHD, and intellectual disability. JAMA. 2024;331(14):1205–1214. doi:10.1001/jama.2024.3172

4. Alemany S, Avella-García C, Liew Z, et al. Prenatal and postnatal exposure to acetaminophen in relation to autism spectrum and attention-deficit and hyperactivity symptoms in childhood: meta-analysis in six European population-based cohorts. Eur J Epidemiol. 2021 Oct;36(10):993-1004. doi: 10.1007/s10654-021-00754-4.

5. Ji Y, Azuine RE, Zhang Y, et al. Association of cord plasma biomarkers of in utero acetaminophen exposure with risk of attention-deficit/hyperactivity disorder and autism spectrum disorder in childhood. JAMA Psychiatry. 2020;77(2):180–189. doi:10.1001/jamapsychiatry.2019.3259