Science Vs (Spotify Studios)

Episode: Does Tylenol Cause Autism?
Date: September 18, 2025
Hosts: Meryl Horne (filling in for Wendy Zuckerman), Rose Rimler
Guest: Dr. Brian Lee, Professor of Epidemiology, Drexel University

Overview: Main Theme & Purpose

This episode tackles claims circulating in the media and social media that taking Tylenol (acetaminophen) during pregnancy may increase the risk of autism in children. Prompted by news of a pending U.S. Government report and rising public anxiety, Science Vs examines the scientific evidence behind the headlines—exploring where this claim comes from, what the best studies show, and what pregnant people should actually do.

The episode breaks down the complexities of the research linking acetaminophen and neurodevelopmental disorders like autism and ADHD. It separates fact from speculation and addresses the role of confounding factors like genetics, maternal age, and illness during pregnancy.

Key Discussion Points & Insights

1. Origins of the Tylenol-Autism Claim

• The idea that acetaminophen (Tylenol) use in pregnancy might cause neurodevelopmental issues has appeared in scientific literature for over a decade ([05:42]; Dr. Lee).
• Early concerns: Some studies found links to sex hormone issues and certain birth defects, like undescended testicles in males ([06:06–08:06]).
• Acetaminophen was long believed to be the "safer" painkiller during pregnancy compared to ibuprofen ([06:19]).
• Researchers speculated acetaminophen could act as an endocrine disruptor, similar to phthalates ([07:09]).

2. Early Studies and Mixed Findings

• Studies from the past 10–15 years produced inconsistent results; some suggested a higher autism risk, especially when paired with hyperactivity or in males, but findings weren't conclusive ([09:00–09:37]).
• Other studies found a stronger correlation with ADHD than autism ([09:56]).
• Dose-response signals suggested more frequent or prolonged acetaminophen use might show higher risk ([10:06]).

3. "Consensus Statement" and Scientific Backlash

• In 2021, a highly publicized consensus statement published in a prestigious Nature journal called for precautionary reduction of acetaminophen use during pregnancy ([10:09–11:08]).
• This statement got widespread scientific attention and led to lawsuits demanding product warning labels ([11:08]).
• Many experts objected, calling the evidence "weak, inconsistent, and to a large extent, methodologically inadequate" ([11:42]).
• Notable quote:

  "[The consensus statement] gave it like a stab of authority." – Dr. Lee, [10:50]
  "The answer right now points towards no." – Dr. Lee on Tylenol causing autism, [12:25]

4. A Landmark Study: Sweden Sibling Analysis

• Dr. Brian Lee and Swedish colleagues leveraged Sweden's detailed medical records to examine 2.5 million births over 24 years ([15:08]).
• Initial findings: Kids exposed to acetaminophen in utero had a 20–30% higher autism risk ([15:46]).
• Confounders examined: When adjusting for maternal age and health conditions, the risk dropped to about 5% ([17:38]).

  "When it's down to, like, a 5% increase in risk, you start to actually wonder whether or not it's real or not." – Dr. Lee, [17:38]

• Sibling comparison: Looking within families—comparing siblings with and without in utero exposure—eliminated the association completely; the risk "flatlined" ([19:30]).

  "Everything flatlined in terms of risk... absolutely no difference in risk for a child who is exposed." – Dr. Lee, [19:30]

5. Alternate Explanations & Genetics

• Genetic factors are overwhelmingly significant, accounting for 70–90% of autism risk ([18:18]).
• There's a plausible third-variable effect: Parents with autism traits (and associated pain/migraines) may be more likely to need acetaminophen, inflating association in observational data ([21:04]).

6. Meta-Analyses and Remaining Debate

• Some systematic reviews still suggest a link, but Dr. Lee critiques these, noting that "garbage in, garbage out"—meta-analyses can't correct for weak or confounded studies ([22:30]).
• Recent Japanese research using similar sibling designs also found no increased risk ([23:31]).

7. Clinical Guidance & Practical Takeaways

• Big medical groups, the FDA, OB-GYN organizations, and European regulators agree: No credible evidence links acetaminophen use in pregnancy to autism or neurodevelopmental disorders ([24:35]).
• Studies that found risk only did so with high, prolonged exposure.
• Untreated high fever during pregnancy poses real risks, including birth defects and possibly increased autism risk ([25:31]).

8. Impact of Blame and Anxiety

• Dr. Lee emphasizes the real harm of misplaced guilt on parents:

  "Blame is damaging, it's harmful... if we can help take away some of that guilt, I think that's nice because people shouldn't be feeling guilty about these things in the past." – Dr. Lee, [26:23]

Notable Quotes & Memorable Moments

| Timestamp | Quote | Speaker | |-----------|-------|---------| | [12:25] | "The answer right now points towards no." | Dr. Brian Lee | | [10:50] | "Up until that point, most people just... you aren't really sure what to believe or not. But once the consensus statement came out, it gave it like a stab of authority." | Dr. Brian Lee | | [17:38] | "When it's down to, like, a 5% increase in risk, you start to actually wonder whether or not it's real or not." | Dr. Brian Lee | | [19:30] | "Everything flatlined in terms of risk... absolutely no difference in risk for a child who is exposed." | Dr. Brian Lee | | [22:30] | "[Meta-analysis is] a garbage in, garbage out kind of a thing. You can feed it garbage, but your meta-analysis is not going to turn this garbage into something beautiful." | Dr. Brian Lee | | [26:23] | "Blame is damaging, it's harmful... people shouldn't be feeling guilty about these things in the past." | Dr. Brian Lee | | [24:35] | "Big medical groups agree here. They say that we don't have evidence that taking acetaminophen during pregnancy causes autism or issues with the development of the fetus." | Meryl Horne |

Timestamps for Key Segments

• Opening/Setting the Stage – [00:00–04:29]
• Science: Early Concerns and Studies – [05:03–11:03]
• Consensus Statement & Backlash – [10:09–12:05]
• Landmark Swedish Study Details – [14:17–21:04]
• Genetics and Sibling Analysis – [18:18–19:45]
• Meta-Analysis Critique & New Japanese Study – [22:30–23:31]
• Medical Consensus and Practical Advice – [24:35–25:56]
• Psychological Impact & Guilt – [26:23–26:59]
• Citations & How to Learn More – [27:01–27:44]

Conclusion: Bottom Line

Does Tylenol Cause Autism?

• Current scientific evidence, especially rigorous sibling-comparison studies, finds no credible causal link between acetaminophen use in pregnancy and risk of autism or ADHD in children.
• Early studies may have been confounded by genetics, maternal health, or environmental factors.
• Pregnant people should not blame themselves for taking Tylenol and should focus on treating conditions (like fever) that are proven to harm pregnancy outcomes.
• Medical authorities' guidance remains unchanged: acetaminophen is considered safe to use in moderation during pregnancy.

For listeners seeking more details or citations, check the full transcript and episode notes in your podcast app.