Paracetamol and Autism: What’s the hype?
Author: Shubhankar Kunte
Think of the most used medicine in a regular household. Did you think of paracetamol (acetaminophen)? I did. Once a staple in every family’s medicine cabinet, it’s now the subject of a baseless smear campaign - a wave of misinformation that twists scientific uncertainty into fear. We find ourselves in strange times, where even something as unremarkable as a fever tablet has become politicised.
Figure 1. Person giving another person a medicine [7].
In 2025, several health-related statements were published by the US government. One of these announcements, backed by the HHS Secretary, was about the effect of acetaminophen use during pregnancy on the nervous system of a developing foetus [1]
The evidence that these statements are based on comes from two large scale studies that focused on specific population cohorts—the Boston Birth Cohort [2] and the Nurses’ Health Study II [3]. These studies reported an association between foetal exposure to paracetamol / acetaminophen and later diagnoses of Autism Spectrum Disorder (ASD) and Attention deficit hyperactivity disorder (ADHD) [2,3].
Let’s take a detailed look at these studies.
The Boston Birth Cohort [2] followed around 1,000 mother–infant pairs and reported an association between maternal use of paracetamol during pregnancy and a higher likelihood of autism or ADHD in children. Rather than relying on memory or questionnaires, researchers measured acetaminophen by-products directly in umbilical cord blood at birth.
Figure 2. Pregnant woman smiling indoors in warm lighting [5].
However, an important limitation of this study is that all participating mothers had some level of acetaminophen exposure. Because there was no truly unexposed comparison group, the researchers could only compare higher versus lower exposure; not exposure versus no exposure at all. This makes it difficult to determine whether acetaminophen itself played a role, or whether another factor common to all participants was responsible for the observed association.
The Nurses’ Health Study II [3] examined whether regular paracetamol use during pregnancy was linked to ADHD in children. To test whether this association was simply due to background factors like genetics or maternal health, the researchers compared paracetamol use during pregnancy with use several years before and after pregnancy. They found that only use during pregnancy showed an association. This suggested that background factors were unlikely to fully explain the result.
This study could not rule out factors unique to pregnancy such as illness, fever, or inflammation. These may require regular paracetamol use and are able to influence child development by themselves. As seen with other observational studies [4], the findings may show a possible association but are unable to establish a cause-effect relationship.
Figure 3. Sick woman lying on the sofa [6].
When considering the results of the studies mentioned above, a common factor blurring the results is the lack of comparison between children exposed to paracetamol in the womb vs those unexposed. This was addressed by a family-based Scandinavian study [4]. They compared siblings, one of them exposed to acetaminophen during pregnancy and one unexposed. This helped adjust for any deviations caused by other familial and environmental factors. [1]
This study found no increased ADHD risk with short-term exposure and an infinitesimally small risk with long-term exposure [4].
Some critics have argued that the statistical methods used in this study might hide a very small but real effect caused by paracetamol exposure during pregnancy. While this is true in a theoretical sense, in epidemiology the effects of certain exposures are consistently observed as causative across different study designs and sample sizes; for example, cigarette smoking and lung cancer.
To conclude, if a causative effect is real but small enough to be masked by statistical methods, it may be true at a biological level but does not carry sufficient weight to raise a public health alarm, as was seen with the paracetamol fact sheet presented by HHS [1].
References
Department of Health and Human Services (US). Autism announcement fact sheet [Internet]. Washington (DC): HHS.gov;2025 Sep 22 [cited 2026 Feb 2]. Available from: https://www.hhs.gov/press-room/autism-announcement-fact-sheet.html
Ji Y, Azuine RE, Zhang Y, Hou W, Hong X, Wang G, 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 [Internet]. 2020 Feb 1 [cited 2026 May 6];77(2):180-90. Available from: https://jamanetwork.com/journals/jamapsychiatry/article-abstract/2753512
Liew Z, Kioumourtzoglou MA, Roberts AL, O’Reilly EJ, Ascherio A, Weisskopf MG. Use of negative control exposure analysisto evaluate confounding: an example of acetaminophen exposure and attention-deficit/hyperactivity disorder in Nurses’ Health Study II. Am J Epidemiol. 2019 Apr;188(4):768-75.
Gustavson K, Ystrom E, Ask H, Ask Torvik F, Hornig M, Susser E, et al. Acetaminophen use during pregnancy and offspring attention deficit hyperactivity disorder – a longitudinal sibling control study. JCPP Adv [Internet]. 2021 Jun 22 [cited 2026 May 6];1(2):e12015. Available from: wiley.com
Da Silva Lopes F. Pregnant woman smiling indoors in warm lighting [photo on the Internet]. Pexels; 2024 Nov 3 [cited 2026 May 6]. Available from: https://www.pexels.com/photo/pregnant-woman-smiling-indoors-in-warm-lighting-29208528/
Danilyuk P. Sick woman lying on the sofa [photo on the Internet]. Pexels; 2021 Feb 8 [cited 2026 May 6]. Available from:https://www.pexels.com/photo/sick-woman-lying-on-the-sofa-6753238/
Danilyuk P. Person giving another person a medicine [photo on the Internet]. Pexels; 2021 Feb 8 [cited 2026 May 6], Available from: https://www.pexels.com/photo/person-giving-another-person-a-medicine-6753297/