Tylenol and Autism: FDA Warning Claims Fact-Checked

I. The September 2025 Announcement

In a joint press conference, President Trump and HHS Secretary RFK Jr. announced that the FDA would issue new warnings about acetaminophen use during pregnancy. Kennedy stated that the drug was a "major contributor" to what he termed the "autism epidemic." [1]

What Was Claimed:

• Tylenol during pregnancy "causes" autism
• This is a newly discovered risk
• The FDA would issue formal warnings
• Parents should avoid acetaminophen entirely during pregnancy

Expert Response:

The American College of Obstetricians and Gynecologists (ACOG) responded swiftly: "Today's announcement is not backed by the full body of scientific evidence." [9]

The Autism Science Foundation called the claims "disingenuous and misleading": "To simplify it and boil it down to 'It's just acetaminophen' ignores the complex, multifactorial nature of autism." [8]

II. What the Science Actually Shows

The scientific literature on acetaminophen and neurodevelopment is more nuanced than the administration's claims suggest. [3]

Association Studies (Earlier Research)

Several observational studies from 2013-2021 found statistical associations between prenatal acetaminophen exposure and increased risk of ADHD, autism spectrum disorder, and other neurodevelopmental conditions. These studies observed correlations but could not establish causation. [10]

The 2024 JAMA Swedish Study

The most rigorous study to date, published in JAMA in 2024, examined 2.4 million Swedish children using advanced methodology: [4]

• Population-level analysis: Initially showed association (like previous studies)
• Sibling control analysis: Compared children whose mothers used acetaminophen during some pregnancies but not others
• Key finding: The association disappeared when genetics were controlled

Dr. Zeyan Liew of Yale School of Public Health, a leading researcher in this field, stated: "We cannot prove a causal relationship between acetaminophen use during pregnancy and autism at this time." [7]

III. The Confounding Factor Problem

The fundamental issue with observational studies on this topic is confounding by indication - the very reasons pregnant women take acetaminophen may themselves be associated with neurodevelopmental outcomes. [5]

Key Confounders:

1. Infection During Pregnancy: Women who take more acetaminophen often have more infections or fevers during pregnancy. Research shows that maternal infection itself is associated with increased neurodevelopmental risk - independent of any medication. [15]

2. Genetic Factors: The sibling control study found that when comparing children from the same mother (sharing genetics and environment), the acetaminophen-autism association vanished. This suggests genetics explain the correlation, not the medication. [11]

3. Recall Bias: Parents of children diagnosed with autism may be more likely to recall and report medication use during pregnancy, skewing observational study results.

4. Chronic Pain Conditions: Women with chronic pain take more acetaminophen and may have underlying conditions that independently affect fetal development.

IV. The Complexity of Autism

The claim that Tylenol "causes" autism ignores the fundamental complexity of autism spectrum disorder. [14]

What Science Has Established:

• Hundreds of genes have been linked to autism risk
• Autism is highly heritable - genetics explain 80-90% of risk
• Multiple environmental factors may play modest roles
• No single cause has been identified
• Autism develops prenatally, before most medication exposure

The Autism Science Foundation emphasized: "Autism is not caused by any single factor. The scientific evidence points to a complex interplay of genetic and environmental factors, with genetics playing the dominant role." [8]

V. Medical Context: Why This Matters

Acetaminophen is one of the few pain relievers considered safe during pregnancy. The alternatives - NSAIDs like ibuprofen and aspirin - carry documented risks including: [16]

• Increased risk of miscarriage
• Heart defects
• Kidney problems
• Premature closure of the ductus arteriosus

ACOG warned that the FDA announcement could lead pregnant women to avoid necessary pain treatment or turn to more dangerous alternatives. [9]

Kenvue (Tylenol Manufacturer) Statement:

Kenvue, the company that makes Tylenol, stated: "We believe there is no causal link between acetaminophen use during pregnancy and autism or ADHD in children. The scientific evidence does not support such a conclusion." [12]

VI. The Litigation Context

Thousands of lawsuits have been filed against Tylenol manufacturers, claiming the drug caused autism and ADHD. Understanding this litigation context is important: [13]

• Over 2,000 cases consolidated in federal court
• Bellwether trials were scheduled for 2024-2025
• Plaintiffs rely on the same observational studies discussed above
• Scientific experts for defendants cite the sibling control studies

Chemical & Engineering News noted that the lawsuits have helped fund and amplify claims about acetaminophen, creating a circular dynamic where litigation publicity drives more studies, which drive more litigation. [10]

VII. Final Verdict

The Evidence Shows:

• No causal link established between acetaminophen and autism
• Association disappears when genetic factors controlled
• Confounding factors (infection, genetics) explain correlations
• Major medical organizations reject the causal claim
• Autism is complex with hundreds of genetic factors

What the Announcement Got Wrong:

• Conflated association with causation
• Ignored the most rigorous research (sibling control studies)
• Oversimplified autism's multifactorial etiology
• May lead to worse health outcomes for pregnant women