The Tylenol–Autism Pseudoscience Pipeline
How false testimony about Tylenol and autism failed in court, was repackaged as “peer-reviewed” junk science, and is now driving Trump’s dangerous medical advice.
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Yesterday, Donald Trump held a lengthy press release where he spewed a lot of disinformation and gave dangerous medical advice. He told people that you shouldn’t take acetaminophen (paracetamol for you European folks) during pregnancy because it causes autism.
Trump’s solution? Just grit your teeth. Pregnancy might be “uncomfortable” without pain and fever relief, but you can just suck it up, right?
Let’s be clear: that claim is false, unsupported by evidence, and harmful. Acetaminophen is the only recommended pain and fever reducer in pregnancy, and untreated fever and pain pose legitimate risks to pregnancy outcomes.
So where did Trump get this idea? Straight from the pseudoscience litigation playbook that RFK Jr and his buddies have profited from for decades.
The proof that Trump, RFK Jr, and MAHA allies are using to claim Tylenol causes autism is a paper published in BMC Environmental Health in August. The paper does not prove this, and it isn’t new data. It’s actually a very poor review of existing studies that tries to claim a link between Tylenol use in pregnancy and autism that the studies themselves don’t support. And it’s not the first time the senior author, Andrea Baccarelli, has tried this.
Demonizing Tylenol in Pregnancy isn’t New
In 2023, hundreds of lawsuits were lumped together in a multi-district litigation (MDL): In re: Acetaminophen – ASD/ADHD Products Liability Litigation.
Parents were suing based on the claim that that taking Tylenol during pregnancy caused autism or ADHD in their children. As such, the manufacturer of Tylenol (McNeil/Kenvue/Johnson & Johnson) and Walmart (that sells it) were to blame because they didn’t warn them.
The plaintiffs and their lawyers used “expert witnesses” to try to show a causal relationship. In this case, that question was whether there was a causal relationship between Tylenol use during pregnancy and autism.
Among the paid witnesses was Andrea Baccarelli, an endocrinologist with no toxicology or pharmacology background who proclaims to be an expert in “environmental exposures.”
His testimony claiming Tylenol use in pregnancy was associated with autism was junk.
He cherry-picked weak observational studies that found associations.
He brushed past far more rigorous studies that found no association at all.
He lumped autism and ADHD together as if they were the same disorder.
He ignored obvious confounders that have known relationships to autism like genetics, maternal illness, or fever (the reason people would use Tylenol in the first place).
Federal Judge Denise Cote rejected his testimony (and that of the other four witnesses) because they did not adhere to the Daubert standard — criteria used in trials when an ‘expert’ is presenting scientific evidence to assess whether the methodology is valid, if it is applicable to the topic at hand, or if they are merely using an appeal to authority to try to legitimize unsupported and unsubstantiated claims.
TL;DR: they were manipulating bad science to push a false narrative.
Since the entire group of lawsuits was based on these expert testimonies and since the testimonies were not based on credible data, the lawsuits got rightly thrown out.
The Tort Litigation Pseudoscience Pipeline is Lucrative
For most people, that would have been the end. But this wasn’t a one-off for Baccarelli — it’s part of a deliberate, profitable industry, one that is exploited by far too many with science or health credentials.
Here’s how it works:
Produce weak research as an academic researcher, usually relying on observational studies with soft endpoints or survey-based qualitatitive data, under the umbrella of studying “environmental exposure” or “exposure science.”
Serve as a paid expert witness in lawsuits against chemical, pharmaceutical, consumer product companies, citing their weak research as evidence.
When testimony gets tossed out for methodological failures, repackage and publish it in a predatory journal as a peer-reviewed paper. Now it can be cited in future cases as “published evidence.”
Use the paper in new lawsuits or lobbying efforts as “proof” of these claims that are not supported by robust data.
The cycle continues….
This is why you often see the same names repeated, people with MDs or PhDs with no credible expertise in toxicology or pharmacology self-branding as “environmental exposure experts.”
It’s a cottage industry built around lawsuits, not science. And it’s lucrative: expert witnesses get paid hundreds of dollars an hour in consulting fees. They also get press attention in their job at their academic institute, ensuring they can continue to get funding to conduct their unscientific “studies” to keep filling their resume. These individuals work hand-in-hand with tort lawyers to profit off pseudoscience, chemophobia, and clickbait.
This is the exact model RFK Jr. has used for decades: manufacture doubt around vaccines, chemicals, and consumer products; find “experts” willing to testify; and use litigation and settlements as both funding and amplification. He’s targeted vaccines, glyphosate, genetic engineering, fluoride—and now Tylenol.
A Paper that Repackaged Tossed Out Testimony
Fast-forward to August 2025. Baccarelli is a senior author on a systematic review in BMC Environmental Health, the paper being cited as “proof” there is a link between acetaminophen use in pregnancy and autism. But it isn’t proof.
It reviews 46 studies, assigns a rating for bias (based on the authors’ judgment), and concludes there are “consistent associations” between prenatal acetaminophen and ADHD, with more tentative evidence for autism.
To be clear: there still isn’t a link between prenatal acetaminophen and autism.
Here’s what the review really does:
It still discards or downplays the largest, most rigorous studies that show no association, including a recent cohort study in JAMA that included nearly 2.5 million children and compared between siblings, an incredibly strong normalization method.
It relies heavily on studies whose data center on self-reported recall of Tylenol use years after pregnancy. If you can’t guess, this is an incredibly weak way to measure exposure, since people’s memories are notoriously fallible.
It’s functionally the same testimony Judge Denise Cote tossed in 2023, now with the appearance of legitimacy. He separated ASD and ADHD and briefly acknowledges studies that find no association, but then concludes there is a “consistent positive association” — essentially throwing out the largest and most rigorous studies that refute that.
Why publish it? Because now it can be cited in lawsuits and political rhetoric as “peer-reviewed evidence.”
BMC Environmental Health isn’t a blatant predatory journal, but it charges ~$3,000 per article and has a track record of publishing weak, “positive association” papers about chemicals and scary health outcomes without real-world evidence.
BMC Journals have a history of numerous retractions due to poor methodology, compromised peer review processes, and failed fact checks. In 2015, 43 papers were retracted because of fake peer review. In 2016, 58 papers were retracted for fake peer review, manipulated authorship, and plagiarism. In 2024, 10 editors of BMC Pregnancy and Childbirth and BMC Women’s Health resigned en masse because they reported data fabrication and the journal refused to respond.
BMC Environmental Health is an ideal place to launder junk science into something with a “peer-reviewed” stamp, because if you didn’t know the history, it looks legit at face value.
Baccarelli’s courtroom claims that had no scientific credibility were repackaged, polished, and published. This is a deliberate legal strategy to fuel pseudoscience, chemophobia, and lawsuits built on unfounded fears. Media outlets and academic institutes are directly contributing to this, by branding this predatory publication as a “Harvard study” (that’s where Baccarelli works) without giving it any degree of scrutiny.
From Predatory Publication to Federal Health Policy
But it’s worse than that. Because now, Trump, Marty Makary, RFK Jr, and our captured health agencies are using this paper as proof Tylenol causes autism. It doesn’t. But because it’s “peer-reviewed,” it is going to be weaponized, doesn’t matter than the author has serious conflicts of interest and the journal is pay-to-publish.
Trump is already spreading deadly medical advice based on this. The White House published their “Autism Action Plan” which includes adding warning labels on acetaminophen.
And let’s not forget the kicker: the “treatment” they claim works: leucovorin, aka folinic acid (not folic acid). Leucovorin (regulated folinic acid) does have some medical indications, but they aren’t to treat or cure autism.
But that didn’t stop Marty Makary, grifter extraordinaire, from bypassing ALL scientific and regulatory guardrails to initiate a process to grant FDA approval for leucovorin for autism symptoms and cerebral folate deficiency.
It gets even better. You’ve got a wellness industry supplement marketplace that is ready to capitalize on this by selling folinic acid supplements (that means they haven’t even passed basic safety scrutiny)
That includes Mehmet Oz (he runs Centers for Medicare and Medicaid Services, btw) who has a financial stake in the company iHerb that… you guessed it: sells folinic acid supplements.
This adoption of health disinformation by what should be bastions of scientific rigor is egregious — and it will cause so much harm to countless people, all while the individuals who fabricate and propagate these falsehoods get richer and richer.
Tylenol does not cause autism. Neither do vaccines, trace pesticide residues, or the nebulous “chemical exposures” fearmongers love to blame.
The strongest predictor of autism is genetics. Twin studies show that if one identical twin has ASD, the other has a 90–99% chance as well, compared with 31–67% for fraternal twins. That’s consistent with an average genetic heritability of 83%. Non-twin siblings have about a 20% likelihood of ASD, which is a seven-fold increase over the general population. The likelihood increases further in families with multiple members with ASD. Over 100 genes have been implicated, many involved in early brain development and neural communication.
Environmental exposures in a household isn’t a driving factor. And blaming “chemicals” isn’t science — it’s distraction.
What can increase likelihood of ASD and autism? Factors that impact fetal development, like maternal fever and infection. Ironically, these are some of the very reasons pregnant people take Tylenol in the first place. Funny how Baccarelli left that out.
So let’s be clear: autism is overwhelmingly genetic, sometimes influenced by biological and developmental factors like maternal fever, but not acetaminophen.
I wrote a lot more about causes of autism, diagnostic criteria, and prevalence of autism over time back in April, so read that if you want those data:
Trump, RFK Jr., and their MAHA allies are recycling a dangerous grift.
Tylenol doesn’t cause autism. Weaponizing bad science to score lawsuits, push supplements, and undermine our science and health infrastructure will cause harm.
The science hasn’t changed. Weak observational associations aren’t causation, and the most rigorous studies don’t support a link. What does predict autism? Genetics, family history, and known developmental factors like maternal fever or infection.
And who pays the price? Pregnant patients who are scared, confused, and at risk. Children who will be subjected to treatments with no evidence to support them. Parents who are being told it’s their fault their child is neurodivergent. Our society is made worse every time health disinformation is legitimized.
When pseudoscience wins, public health loses, and people suffer. That’s the goal of this administration.
Last night, I also joined Dr. Kaveh Hoda (hepatologist) and Dr. Ryan Marino (toxicologist) to discuss all of this and more on The House of Pod, so make sure to listen to our discussion as well! (links are below):
Listen on Spotify:
Listen on Apple Podcasts:
We all must join in the fight for science.
Thank you for supporting evidence-based science communication. With outbreaks of preventable diseases, refusal of evidence-based medical interventions, propagation of pseudoscience by prominent public “personalities”, it’s needed now more than ever.
Stay skeptical,
Andrea
“ImmunoLogic” is written by Dr. Andrea Love, PhD - immunologist and microbiologist. She works full-time in life sciences biotech and has had a lifelong passion for closing the science literacy gap and combating pseudoscience and health misinformation as far back as her childhood. This newsletter and her science communication on her social media pages are born from that passion. Follow on Instagram, Threads, Twitter, and Facebook, or support the newsletter by subscribing below:
My guess is that Kennedy’s clown car simply decided that Tylenol was the low hanging fruit they needed for a scalp.
I’m not going to presume to tell you anything you don’t already know about concerns regarding Tylenol (I very much appreciate your efforts and am humbled by your demonstrated proficiency in a wide range of PH topics). Though if I had to guess the direction they’ll go with propaganda is that of oxidative stress > glutathione depletion > autism, regardless that a variety of drugs can be argued to have the same issue.
Thanks again for everything. Your posts are a great resource for me and my MPH offspring.
You have a true gift to be able to communicate all the nuance of the misinformation in such a concise and understandable way. Hopefully the poor souls who actually listen to RFK Jr can comprehend it.