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Eric Feigl-Ding@DrEricDing · Sep 22, 2025

⚠️TYLENOL & AUTISM—RFK Jr and Trump are wrong—the largest & best study in the world in 2.5 MILLION KIDS—found no…

14 tweets2 min read26.8Koriginal

Summary

Large epidemiological studies from Sweden and Norway involving 2.5 million children found no association between acetaminophen (Tylenol) use during pregnancy and autism risk when controlling for family factors, contradicting claims by RFK Jr and Trump. The apparent 5% increased risk in unadjusted analyses disappeared when sibling controls were used, indicating the association was due to confounding rather than a true causal effect.

Summarized by ThreadOut AI from the full thread. May miss nuance — read the thread below.

  1. #1

    ⚠️TYLENOL & AUTISM—RFK Jr and Trump are wrong—the largest & best study in the world in 2.5 MILLION KIDS—found no increased autism risk with acetaminophen (aka paracetamol, Tylenol) use by the mother during pregnancy. A crude unadjusted analysis found only a preliminary 5% risk, but once you adjust for family by matching using sibling controls (who didn’t get autism), the even tiny 5% risk vaporizes to 0% 📉. (Fun fact: I used to do drug safety epidemiology and have been whistleblower against big pharma when their drugs were dangerous—so I know a few things about drug safety data). Thread 🧵.

  2. #2

    2) “To address unobserved confounding, matched full sibling pairs were also analyzed. Sibling control analyses found no evidence that acetaminophen use during pregnancy was associated with autism…” jamanetwork.com/journals/jama/…

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    3) “Conclusions and Relevance  Acetaminophen use during pregnancy was not associated with children’s risk of autism, ADHD, or intellectual disability in sibling control analysis. This suggests that associations observed in other models may have been attributable to familial confounding.” jamanetwork.com/journals/jama/…

  4. #4

    4) Interestingly, there is also no dose-response (higher dose, higher risk) relationship either. A higher dose of acetaminophen did not find a higher risk than a lower dose or medium dose pattern. This also suggests a lack of causality usually. While non linear results can occasionally happen, there usually is a reason, and so a funky unexplained up and down thing with no significant trend is a tell tale sign in epidemiology that Tylenol autism thing ain’t real.

  5. #5

    5) The above study was in Sweden. Meanwhile, did another study find the same phenomenon? Yes, in a Norwegian study, where once you adjust the acetaminophen-autism analysis by family sibling analysis, then the association goes away to a very non-significant null 📉. ➡️Also, short term acetaminophen use under 29 days had no increase risk in either type of analysis. pubmed.ncbi.nlm.nih.gov/37431475/

  6. #6

    6) I will post a more in depth analysis later tonight/tomorrow. Take a moment to subscribe to my Journal. I will publish a debunk on my site shortly. Thanks for your support. drericding.substack.com

  7. #7

    7) Live stream - discussion about Tylenol and autism and the pro death movement with @WajahatAli open.substack.com/live-stream/62…

  8. #8

    @WajahatAli 8) For those wondering my background - I have a doctorate in Epidemiology (and another doctorate in Nutrition) and was a faculty and researcher for 15+ years at Harvard, and was a whistleblower during the Vioxx drug safety debacle versus Merck.

    Eric Feigl-Ding@DrEricDing · Dec 21, 2021

    📝A note—Many say racist things to me—& some folks don’t like I share precautionary/doom-y COVID data. Some call me a CCP spy, pharma shill, attention seeking personal brand builder… But I’m none of those. Who I really am:🧵 This from exactly 10-yrs ago— well.blogs.nytimes.com/2011/12/08/a-w…

  9. #9

    @WajahatAli 9) it’s bleach/HCQ/ivermectin all over again….

    Wajahat Ali@WajahatAli · Sep 23, 2025

    Donald Trump Becomes Dr. Death and Declares War on Tylenol Donald Trump, an ignorant man without any medical experience, repeats dangerous, unfounded, and reckless claims about Tylenol and autism in another step advancing MAGA's pro-death march. With @DrEricDing open.substack.com/pub/thelefthoo…

  10. #10

    @WajahatAli 10) 📍LET’S TALK ABOUT TYLENOL AND AUTISM — quality of the data matters: open.substack.com/pub/drericding…

  11. #11

    @WajahatAli 11) You all need to learn what “confounding” by family differences is in epidemiology. And also confounding by indication of the underlying fever that made the pregnant mom take a Tylenol in the first place… read on:

    Eric Feigl-Ding@DrEricDing · Sep 23, 2025

    💡By popular request, since you’ve asked… here are my longer review of Tylenol and autism… but wait there’s more… open.substack.com/pub/drericding…

  12. #12

    @WajahatAli 12) Oh. Gee. Fun fact—I’ve never been paid for any expert testimony either for/against the maker of Tylenol. statnews.com/2025/09/23/res…

  13. #13

    @WajahatAli 13) This article has NOT been bought and paid for by big pharma or any legal fund. It’s free for all subscribers. drericding.substack.com/p/lets-talk-ab…

  14. #14

    @WajahatAli 14) Boom—the WHO agrees there is no conclusive evidence linking autism with acetaminophen/ paracetamol. RFK Jr and Trump are wrong again.

    World Health Organization (WHO)@WHO · Sep 24, 2025

    WHO statement on autism-related issues The World Health Organization (WHO) emphasizes that there is currently no conclusive scientific evidence confirming a possible link between autism and use of acetaminophen (also known as paracetamol) during pregnancy. Globally, nearly 62 million people (1 in 127) have autism spectrum disorder, a diverse group of conditions related to development of the brain. Although awareness and diagnosis have improved in recent years, the exact causes of #autism have not been established, and it is understood there are multiple factors that can be involved. Extensive research has been undertaken over the past decade, including large-scale studies, looking into links between acetaminophen use during pregnancy and autism. At this time, no consistent association has been established. WHO recommends that all women continue to follow advice of their doctors or health workers, who can help assess individual circumstances and recommend necessary medicines. Any medicine should be used with caution during pregnancy, especially in the first three months, and in line with advice from health professionals. Also, a robust, extensive evidence base exists showing childhood vaccines do not cause autism. Large, high-quality  studies from many countries have all reached the same conclusion. Original studies suggesting a link were flawed and have been discredited.  Since 1999, independent experts advising WHO have repeatedly confirmed that vaccines - including those with thiomersal or aluminum - do not cause autism or other developmental disorders. Childhood vaccine schedules are developed through a careful, extensive and evidence-based process involving global experts and country input. The childhood immunization schedule, carefully guided by WHO, has been adopted by all countries, and has saved at least 154 million lives over the past 50 years. The schedule remains essential for the health and wellbeing of every child and every community. These schedules have continually evolved with science and now safeguard children, adolescents and adults against 30 infectious diseases. Every vaccine recommendation by the Strategic Advisory Group of Experts on Immunization (SAGE), an independent advisory group to WHO, is grounded in rigorous review of evidence and carefully designed to offer the best protection against serious diseases and to be delivered when most needed. When immunization schedules are delayed or disrupted, or altered without evidence review, there is a sharp increase in the risk of infection not only for the child, but also for the wider community. Infants too young to be vaccinated and people with weakened immune systems or underlying health conditions are at greatest risk. Autism and neurodevelopmental disorders are among priority mental health and neurological conditions being discussed at the 4th UN High-Level Meeting on NCDs and mental health this Thursday, 25 September. As a global community, we need to do more to understand the causes of autism and how best to care for and support the needs of autistic people and their families. WHO is committed to advancing this goal working together with partners including autistic-led organizations and other organizations representing persons with lived experience. WHO also stands with people who are living with autism and their families, a dignified community entitled to evidence-based considerations free of stigma. Full statement: bit.ly/47YsgwI