Is Tylenol (acetaminophen) linked to autism?

Acetaminophen and Autism: Current Evidence

Based on the most recent and highest quality evidence, acetaminophen (Tylenol) use during pregnancy is not associated with increased risk of autism spectrum disorder in children. 1

Evidence Overview

The relationship between prenatal acetaminophen exposure and neurodevelopmental outcomes has been extensively studied with mixed results until recently:

• Earlier studies and reviews suggested potential associations between prenatal acetaminophen use and neurodevelopmental disorders, including autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) 2, 3
• Some studies reported increased risk ratios for ASD (1.19) and ADHD (1.28-1.34) with prenatal acetaminophen exposure 2
• A Danish cohort study found an association specifically with ASD accompanied by hyperkinetic symptoms (HR = 1.51), but not with other ASD cases 4

Most Recent Evidence

The most recent and methodologically robust evidence comes from a 2024 nationwide cohort study with sibling control analysis that included 2,480,797 children born between 1995-2019 in Sweden 1:

• This study specifically addressed familial confounding through sibling control analysis
• While initial models showed marginally increased risks (HR 1.05 for autism)
• Sibling control analyses found no evidence that acetaminophen use during pregnancy was associated with autism (HR 0.98,95% CI 0.93-1.04)
• No dose-response relationship was observed in sibling control analyses
• The study concluded that previously observed associations were likely attributable to familial confounding factors

Clinical Recommendations

Based on the current evidence:

1. Acetaminophen remains the safest medication option for necessary pain or fever relief during pregnancy 3
2. The Society for Maternal-Fetal Medicine (SMFM) and American College of Obstetricians and Gynecologists (ACOG) continue to recommend acetaminophen as a reasonable and appropriate medication choice for treating pain/fever during pregnancy 3

Important Considerations

• Use acetaminophen judiciously during pregnancy:

  • Use the lowest effective dose for the shortest possible time
  • Avoid prolonged use without periodic evaluation of continued need
  • Consider non-pharmacological approaches for mild to moderate pain when appropriate

• The conditions requiring acetaminophen (fever, inflammation) may themselves contribute to neurodevelopmental outcomes 3

Common Pitfalls

1. Confusing correlation with causation: Earlier studies showing associations failed to adequately control for familial confounding factors
2. Ignoring indication bias: The medical conditions requiring acetaminophen use may themselves influence neurodevelopmental outcomes
3. Overlooking recent evidence: The 2024 study 1 provides the strongest evidence to date with its large sample size and sibling control design

The weight of evidence, particularly from the most recent and methodologically robust research, does not support a causal relationship between prenatal acetaminophen use and autism in offspring.