Does Tylenol (Acetaminophen) Cause Autism?
The highest quality evidence from a 2024 nationwide Swedish cohort study with sibling control analysis found no causal association between acetaminophen use during pregnancy and autism, ADHD, or intellectual disability in children. 1
Key Evidence from the Most Recent High-Quality Study
The 2024 JAMA study analyzed 2.48 million children and is the most methodologically rigorous investigation to date because it used sibling control analysis to account for familial confounding 1:
- In sibling-matched analysis, acetaminophen exposure showed no increased risk for autism (HR 0.98,95% CI 0.93-1.04), ADHD (HR 0.98,95% CI 0.94-1.02), or intellectual disability (HR 1.01,95% CI 0.92-1.10) 1
- No dose-response relationship was found - children with low, medium, and high acetaminophen exposure had hazard ratios of 0.85,0.96, and 0.88 respectively for autism 1
- The study concluded that associations observed in earlier studies were likely due to familial confounding factors rather than acetaminophen itself 1
Why Earlier Studies Showed Associations
Previous observational studies reported modest associations, but these had critical methodological limitations 2:
- Earlier studies lacked sibling controls and could not account for shared genetic and environmental factors within families 1
- Risk ratios in prior systematic reviews ranged from 1.09-1.19, but these were based on studies with self-reported acetaminophen use and recall bias 2
- The 2016 Danish cohort study found associations only with ASD accompanied by hyperkinetic symptoms (HR 1.51), not with ASD alone 3
Current Clinical Guidance
The Society for Maternal-Fetal Medicine and FDA have concluded that the weight of evidence is inconclusive regarding a connection between acetaminophen use in pregnancy and neurodevelopmental disorders 2:
- Acetaminophen remains a reasonable and appropriate medication choice for treating pain and fever during pregnancy 2
- Use at the lowest effective dose for the shortest possible duration 2
- Communication regarding risks versus benefits should occur between patient and provider 2
Common Pitfalls to Avoid
- Do not withhold necessary pain or fever treatment based on earlier observational studies that did not control for familial confounding 1
- Do not assume causation from correlation - the apparent associations in earlier studies likely reflected unmeasured confounders such as the underlying maternal illness requiring treatment, genetic factors, or other shared family characteristics 1
- Recognize that untreated maternal fever and pain carry their own risks to pregnancy outcomes 2
The Bottom Line for Clinical Practice
The 2024 sibling-controlled study provides the strongest evidence to date and effectively refutes the hypothesis that acetaminophen causes autism 1. While prudent use of any medication during pregnancy is warranted, there is no credible evidence supporting acetaminophen as a cause of autism when accounting for familial confounding factors 1.