Originally published on www.sayerji.substack.com
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Tylenol and Autism, Part II: The Swedish Study That Got It Wrong
As first reported in the WSJ, a breaking HHS report under RFK Jr. will officially tie prenatal Tylenol use to autism--sending Kenvue's stock plummeting--and vindicating researchers who've warned for years of acetaminophen's hidden dangers to developing brains.
It's official: after years of dismissal by the medical establishment, the U.S. Department of Health and Human Services (HHS) is finally preparing to publicly acknowledge an association between acetaminophen (Tylenol) use in pregnancy and autism. U.S. Health Secretary Robert F. Kennedy Jr. will reportedly announce an HHS report linking prenatal Tylenol exposure to autism spectrum disorder (ASD) in children. The mere news of this impending announcement has sent shockwaves through both the medical community and Wall Street. In fact, shares of Kenvue -- the new parent company of Tylenol -- plunged around 10% on the report, hitting their lowest levels since the company's spinoff. This immediate market reaction is a telling sign: investors understand that the liability and public health implications are enormous, and that years of warnings about acetaminophen's neurotoxic risks are being dramatically vindicated.
For those of us at GreenMedInfo, who have long tracked concerns about Tylenol's safety, this development is both groundbreaking and bittersweet. Autism diagnoses have exploded from about 1 in 1,000 children in the early 1990s to roughly 1 in 31 children today1, and the official stance has always been that the causes are "unknown" or purely genetic. If a common over-the-counter drug like Tylenol is even partially responsible for this epidemic, acknowledging that link publicly marks a seismic shift in public health policy. It also raises an urgent question: How many of these children's lives might have been different if our health authorities had heeded the warning signs sooner?
IMPORTANT NOTE: We welcome HHS's move on Tylenol -- and we also emphasize the multi-factorial nature of autism risk. In our synthesis, vaccination exposures represent the primary causal driver, compounded by prenatal ultrasound, C-section-related stressors, acetaminophen, and other environmental/iatrogenic factors (we have 50+ indexed on our Autism Spectrum Disorder Database).
GreenMedInfo's Two-Decade Crusade on Acetaminophen Risks
As someone who has been writing about natural and integrative health for well over thirty years, I can say this moment feels like a vindication. We at GreenMedInfo have been sounding the alarm on Tylenol's brain and behavioral risks for nearly two decades, long before any government agencies or mainstream journals would entertain such a connection. In the early 2000s, hints of trouble began emerging -- observant clinicians and researchers posited that the rise in routine Tylenol use (especially after aspirin was shunned in the 1980s) might be contributing to surging neurodevelopmental problems. By 2008, the first peer-reviewed paper had been published suggesting a link between early acetaminophen exposure and neuropsychiatric disorders (a study by Stephen Schultz and colleagues). Throughout the 2010s, study after study from around the world reported associations between prenatal acetaminophen and conditions like autism, ADHD, and behavioral issues2. We reported on all of it, cataloguing the science as it unfolded.
Yet for years, these warnings were ignored---or actively shot down. The prevailing medical dogma was that acetaminophen is the only truly safe pain reliever for pregnant women. The American College of Obstetricians and Gynecologists (ACOG), for example, has insisted that Tylenol is safe during pregnancy and "one of the only" painkillers that expectant mothers should use. As late as 2021, when a coalition of 91 scientists and clinicians published a consensus statement in Nature Reviews Endocrinology urging caution with acetaminophen use during pregnancy, ACOG (a professional organization heavily funded by pharmaceutical interests) publicly opposed their recommendations. The scientists had warned that prenatal exposure to Tylenol might alter fetal development and increase risks of neurological, urogenital, and reproductive disorders. ACOG's response? To dismiss those concerns and reassure the public that decades of use proved the drug's safety. In effect, the attitude was "Everybody uses Tylenol, so it must be okay" -- a lazy and dangerous assumption that we have challenged at every turn3.
GreenMedInfo's independent research database has amassed dozens of citations on acetaminophen's hidden toxicity. You can review ~300 peer-reviewed studies on Tylenol's broad spectrum toxicity on our database dedicated to the subject here.
Back in 2018, we published a widely-read article by Duke University scientist William Parker, Ph.D. titled "Tylenol Damages the Brains of Children, Research Reveals." In it, Dr. Parker laid out a litany of concerns, from epidemiological studies linking Tylenol to autism/ADHD, to mechanistic insights about how the drug can induce oxidative stress in the brain4. He pointed out that as of 2017, every single study examining acetaminophen's long-term effects on child neurodevelopment had found evidence of harm -- not a single one showed it to be safe5. These studies weren't cherry-picked anomalies; all the data were pointing in the same troubling direction, even after adjusting for confounding factors like the illnesses or fevers that led the mothers to take Tylenol in the first place6.
In 2019, I penned a piece titled "Consumer Alert: Tylenol's Empathy-Killing Properties Confirmed in 2nd Study,"highlighting a startling psychological side effect (more on that later) of this over-the-counter drug. And going back even further, we have repeatedly raised questions about acetaminophen's role in everything from asthma to infertility to Reye's syndrome alternatives. Time and again, our reporting was met with skepticism or silence. We were "alarmist," they said. After all, how could something so common and doctor-endorsed possibly be harmful? In mainstream media coverage, it was typical to see an obligatory quote from an expert asserting that no causal link had been proven and that pregnant women should not worry. These "experts" often had not spent any real time poring over the literature on acetaminophen's neurotoxicity; they were simply parroting the conventional wisdom (or the party line) that they themselves had been taught7. In essence, the false reassurance machine was in full force -- "If it were dangerous, surely we'd know by now!"
Well, it turns out we did know. The data were there all along for those willing to look. And now with HHS preparing to take a public stance, it appears the truth can no longer be denied.
The Science: How Acetaminophen Harms Developing Brains
Prenatal Tylenol Exposure Linked to Autism and ADHD
Let's dig into the science that brought us here. Acetaminophen (paracetamol) is one of the most widely-used drugs in the world, especially by pregnant women and children. Over the past 10-15 years, a growing number of studies have examined whether prenatal exposure to this drug might be affecting childhood brain development. The results have been alarming and strikingly consistent. By 2022, more than 20 peer-reviewed studies had reported statistically significant associations between maternal acetaminophen use and increased rates of neurodevelopmental disorders (NDDs) in offspring. These NDDs include autism spectrum disorder (ASD) and attention deficit/hyperactivity disorder (ADHD), primarily, but some studies also noted impacts on language delays, behavioral problems, and lower IQ.
For example, a 2018 systematic review and meta-analysis led by researchers at Hebrew University (Jerusalem) looked at data from over 130,000 mother-child pairs. It found that children whose mothers had used a lot of acetaminophen while pregnant had about a 30% higher relative risk of ADHD and a 20% higher risk of ASD, compared to children not exposed. The following year, a massive birth cohort study at Johns Hopkins (as part of the Boston Birth Cohort) reported that newborns with higher cord blood markers of acetaminophen exposure had significantly higher odds of later being diagnosed with autism or ADHD, with a clear dose-response pattern. And in 2021, another meta-analysis (this one published in the European Journal of Epidemiology) concluded that prenatal acetaminophen exposure is associated with roughly 19% higher odds of autism and 21% higher odds of ADHD -- remarkably similar risk increases to the 2018 analysis.
Most recently, in August 2025, an international team of scientists (from the Icahn School of Medicine at Mount Sinai, Harvard, UCLA and elsewhere) published a comprehensive review of 46 studies investigating acetaminophen use during pregnancy and neurodevelopmental outcomes8. Using the rigorous Navigation Guide methodology for environmental health, they evaluated the quality and consistency of the evidence. Their conclusion could not have been clearer: "evidence [is] consistent with an association between acetaminophen exposure during pregnancy and increased incidence of NDDs"9. In plainer terms, the bulk of the scientific literature now supports a link between prenatal Tylenol and developmental disorders. Out of those 46 studies, 27 found positive associations (more acetaminophen correlated with more neurodevelopmental problems), 9 found no significant link, and 4 oddly suggested a protective effect (the authors noted those 4 "negative" studies tended to be lower-quality)10. The review's authors -- including Dr. Andrea Baccarelli, chair of environmental health at Harvard Chan School -- urged that "appropriate and immediate steps should be taken to advise pregnant women to limit acetaminophen consumption to protect their offspring's neurodevelopment."9 In other words, apply the precautionary principle now, given what the evidence shows.
It's important to note that these human studies are observational in nature (for obvious ethical reasons, we can't do randomized trials where we intentionally expose babies to a potential toxin). Critics often point out that correlation isn't proof of causation. And indeed, researchers have bent over backward to account for confounding factors -- could it be, for instance, that mothers who take Tylenol have more infections or pain, and those underlying issues raise autism risk? So far, the data suggest that acetaminophen itself is the culprit rather than whatever underlying condition prompted its use6. Many of the studies controlled for factors like maternal infections, fevers, use of other medications, etc. One 2016 JAMA Pediatrics study by Evie Stergiakouli et al. even compared women to themselves -- looking at differences in outcome between one of their children exposed in utero to Tylenol and another child not exposed -- finding higher behavior problem scores in the exposed children, effectively controlling for genetic and socioeconomic factors11. Time and again, the association holds. As Dr. Parker summarized in 2018, every well-designed epidemiological study up to that point had pointed toward acetaminophen being neurotoxic to the developing brain⁴. This consistency across different countries and cohorts is part of why experts are now more confident that the link is real, not just a fluke. And now, apparently, HHS agrees.
Before moving on, let's address when the risk is greatest. Interestingly, it's not only prenatal exposure that's concerning. Giving acetaminophen to infants and young children (especially in the first year or two of life) might be just as harmful, if not more so, to neurodevelopment. A recent review noted that the highest risks for autism related to acetaminophen were observed when the drug was given to newborns (e.g. for circumcision pain or fever) and in early infancy, more so than in pregnancy. Why? Possibly because a pregnant mother's metabolism provides some protective buffering (she can help clear the drug), whereas a newborn's immature system is hit with the full brunt of acetaminophen's effects. Indeed, we've written about the troubling practice of routinely giving infants Tylenol right before and after vaccinations, ostensibly to reduce fever or fussiness. Many pediatricians have recommended this for years. Yet acetaminophen depletes glutathione (the body's key antioxidant -- more on that below), potentially hampering a baby's ability to detoxify the ingredients in vaccines (like aluminum and mercury preservatives) and possibly worsening any inflammatory brain reactions. It's a one-two punch we should carefully reconsider. In short, timing matters: the developing brain can be affected by Tylenol in utero and in early childhood, which means caution is warranted across the board in young populations.
The Glutathione Connection: Acetaminophen Depletes the "Master Antioxidant"
What could be causing acetaminophen to have these neurodevelopmental effects? One well-established mechanism is oxidative stress. Acetaminophen is metabolized in the liver through pathways that produce a toxic intermediate (NAPQI), which is normally neutralized by glutathione, a powerful antioxidant tripeptide. Glutathione is often called the "master antioxidant" of the body -- as Dr. Mark Hyman puts it, the "mother of all antioxidants, the master detoxifier". Every cell relies on it to combat oxidative damage and to process toxins safely. When you take acetaminophen, a portion of your glutathione gets used up to safely break down the drug. This is why, in an overdose, acetaminophen can literally destroy the liver -- it depletes glutathione to nothing, and cell damage runs rampant. The standard ER treatment for Tylenol overdose is N-acetylcysteine (NAC), which is a precursor that helps restore glutathione levels.
Learn more about the profound therapeutic properties of NAC on the GreenMedInfo NAC database on the subject below.
Now consider a developing fetus or infant. Their antioxidant defenses are not as robust as an adult's to begin with. Acetaminophen crossing the placenta (it readily does) or given to a baby will lower the availability of glutathioneduring a critical window of brain development. This could leave the brain more vulnerable to other stressors -- say, inflammation from an illness, or environmental toxins like mercury, lead, or pesticide residues. Notably, during pregnancy the fetus is already exposed to a slew of potential toxicants (everything the mother is exposed to, from plastics chemicals to pollution), and many mothers are now also urged to get certain vaccines during pregnancy (flu shots, Tdap), which contain preservatives like mercury (Thimerosal) or adjuvants like aluminum. If the mother takes Tylenol as well -- perhaps to deal with fever or aches from those shots -- it could compound the oxidative burden on the fetus. We at GreenMedInfo have raised this point repeatedly: stacking acetaminophen on top of other exposures is potentially a recipe for trouble. Unfortunately, conventional medicine never considered this possibility until very recently.
Beyond the realm of theory, there's evidence that children with autism and ADHD tend to show signs of oxidative stress and impaired detox pathways. Some studies have found lower glutathione levels or related biomarkers in kids on the autism spectrum. So acetaminophen's glutathione-depleting effect is a biologically plausible trigger or contributor to neurodevelopmental injury. It might be especially relevant in kids who have genetic polymorphisms affecting their antioxidant and methylation pathways (e.g., variants in GST or MTHFR genes). In simpler terms: acetaminophen can turn a manageable stress into a tipping point for some individuals whose ability to neutralize toxins is limited.
Another mechanistic angle is mitochondrial dysfunction. Glutathione depletion can impair mitochondria (the energy factories of cells), and there is substantial research now suggesting that many cases of autism involve mitochondrial dysfunction in the brain. It's not hard to see how Tylenol -- if given repeatedly during development -- might contribute to such issues by creating chronic low-grade oxidative stress.
Boys at Higher Risk? The Hormonal and Epigenetic Factors
It has long been observed that autism affects boys about 3-4 times more frequently than girls. Interestingly, research by Dr. Margaret McCarthy, chair of pharmacology at the University of Maryland, indicates that male brains are considerably more sensitive to acetaminophen's effects than female brains12. This could be one clue to the sex discrepancy in autism rates. McCarthy's lab and others have explored how acetaminophen might interfere with hormones (like testosterone) that are crucial for male brain development in utero12. In male fetuses, a surge of testosterone in mid-gestation helps "masculinize" the brain; anything that blunts that hormone signal could potentially alter the typical neural development trajectory.
Indeed, acetaminophen is now recognized as a potential endocrine disruptor. Studies have shown that prolonged use of acetaminophen during pregnancy can reduce testosterone production by the fetal testicles, leading to effects such as undescended testes (cryptorchidism) in baby boys13. In one notable experiment, researchers grafted human fetal testicular tissue into mice and found that giving the mice therapeutic doses of acetaminophen significantly reduced testosterone levels in that human tissue14. The worry is that disrupting the male hormonal environment in utero could not only cause urogenital abnormalities but also impact brain development, since testosterone influences the formation of male-typical neural circuits. Some have even theorized that the autism spike in the 1980s (when Tylenol began to be heavily used during pregnancy and infancy) disproportionately affected boys partly due to this mechanism. Girls, with generally higher baseline glutathione levels and different hormonal milieu, might be somewhat more protected from acetaminophen's impact -- though they are by no means immune (girls can and do develop autism or ADHD, just at lower rates).
Beyond hormones, epigenetic effects are also being studied. Acetaminophen might induce oxidative stress that leads to subtle DNA methylation changes or other epigenetic modifications during development, altering gene expression in ways that later manifest as neurodevelopmental disorders. Research into these pathways is ongoing, but the takeaway is that acetaminophen's impacts are not limited to the liver -- they extend to hormone systems and the very genetic programming of the developing brain.
Animal Studies: "Cause and Effect" in the Lab
While we obviously can't experimentally give pregnant women Tylenol vs. placebo and see what happens to the kids, scientists have done extensive experiments in animal models -- and the results are deeply concerning. In rodents (mice and rats), exposure to acetaminophen during critical periods of brain development causes long-term changes in behavior and brain chemistry. For instance, Dr. Henrik Viberg at Uppsala University in Sweden has shown that when mice are given acetaminophen as neonates, they later exhibit persistent neurological deficits, including problems with memory and social behavior15. These deficits in mice mirror some of the features of ASD/ADHD in humans (e.g., reduced social play, hyperactivity, etc.). Importantly, the timing of exposure in these animal studies is key -- giving the drug during a narrow developmental window leads to effects that don't occur if you give the same dose to an older animal. That strongly suggests it's the early brain development interference that's the issue.
One study published in 2017 found that male rat pups exposed to acetaminophen in late gestation had altered brain plasticity and subtle cognitive impairments as they grew up, whereas female pups were not as affected -- again pointing to a sex-specific vulnerability. Another study (published in Toxicological Sciences in 2019 by Axelstad et al.) reported that developmental exposure to acetaminophen in rats led to dose-dependent reductions in male behaviors (like less mounting behavior and changed play patterns), consistent with a demasculinization effect of the drug on the brain. These animal findings provide a proof of concept: yes, acetaminophen can directly cause developmental neurotoxicity under experimental conditions.
Critics might argue that rodent studies don't always translate to humans, which is fair. But in this case, the animal results align disturbingly well with the epidemiological trends we're seeing in people. When you have human data and lab data both pointing in the same direction, the argument for causality becomes much stronger. In fact, even some government scientists have raised alarms. A 2022 review in the journal Minerva Pediatrics by a team that included Dr. William Parker (again) laid out 17 distinct lines of evidence -- from biochemistry to population health patterns -- supporting the idea that acetaminophen has contributed to the autism epidemic. Parker bluntly stated that given all we know now, "acetaminophen would never be approved for pediatric use by today's regulatory standards". In other words, if Tylenol were a new drug coming onto the market in 2025, regulators might well reject it for use in children or pregnant women due to red flags in the data. But since it's been sold over-the-counter for generations, we've assumed it must be fine. That complacency is finally crumbling.
A Psychotropic Side Effect: Blunting Pain and Emotion
Most people think of Tylenol as a simple pain and fever remedy with no effects on one's mental state. It's not a narcotic, it's not considered psychoactive. But emerging research has turned that assumption on its head. Acetaminophen, it turns out, has a subtle yet profound effect on psychology: it blunts emotions. The drug doesn't just kill pain -- it dulls our capacity to feel both negative and positive feelings, a phenomenon known as "affect flattening."
The first hint of this came in 2015, when a groundbreaking study in the journal Psychological Science found that college students who took a normal dose of Tylenol (around 1,000 mg) showed less extreme emotional responses to both unpleasant and pleasant stimuli, compared to those who took a placebo. In other words, on acetaminophen they weren't as bothered by distressing things -- but they also weren't as joyful about uplifting things. Their emotional range was compressed.
This was followed by a 2016 study that observed similar effects on social emotions. And then in 2019, a team of researchers published a paper titled "A Social Analgesic? Acetaminophen (Paracetamol) Reduces Positive Empathy,"which zeroed in on empathy specifically. In a randomized trial, participants read scenarios about other people's fortunate experiences (for example, someone describing a happy event). Those who had taken Tylenol beforehand consistently reported diminished empathy -- they felt less happy for the other people or less "moved," compared to participants who took a placebo. The drug users also reported less personal pleasure in response to the stories, indicating that Tylenol was muting their own positive emotions.
Painkiller or Soul-Killer? The Troubling Connection Between Tylenol and Decreased Empathy compiles the 2015 Psychological Science study and the 2019 Frontiers in Psychology trial with plain-language explanation and societal implications.
Neuroscientists have tried to understand why this happens. One clue is that the same brain regions that register physical pain overlap with those that process social and emotional pain. Functional MRI studies show that acetaminophen reduces activation in the anterior insula (AI) and anterior cingulate cortex (ACC) during experiences of pain. Those regions are also crucial for empathy and emotion. So if Tylenol is turning down the dial in the ACC/insula to make your headache bother you less, it's likely also impairing your ability to resonate with others' feelings or even to feel your own highs and lows fully. It's like an emotional anesthetic.
Now, you might ask: so what if Tylenol slightly chills out your feelings for a couple hours? Is that really a big deal? Consider that an estimated 1 in 4 American adults takes an acetaminophen-containing medication every week (often unknowingly, since it's in so many combo products for colds, flu, allergies, etc.). This means at any given moment, a substantial portion of the population is under its influence. The researchers of the empathy study noted that positive empathy -- the ability to share in others' joy -- is part of the "social glue" that bonds people together and promotes prosocial behavior. If a ubiquitous drug is systematically eroding that empathy, even just a bit, the aggregate impact on society could be non-trivial. Think of it: millions of people walking around slightly numbed, less able to connect emotionally.
As the author of that 2020 GreenMedInfo article, I speculated: Could Tylenol be contributing to the epidemic of social disconnection, anxiety, and even aggression we see in modern society? It sounds far-fetched until you realize just how pervasively used this chemical is. When layered on top of other empathy-reducing factors (like social media or certain psychiatric medications), it might be another brick in the wall. I referred to Tylenol's emotion-dulling effect as adding "soul-deadening" properties to its list of side effects -- a stark phrase, but one I stand by. Because what is the soul, metaphorically, if not our capacity to feel and care deeply?
I'm not alone in these concerns. The researchers themselves raised questions about societal impact, noting that the pro-social benefits of shared joy could be undermined by widespread acetaminophen use. To be clear, taking a Tylenol won't turn you into a sociopath. But it might make you a bit more indifferent, less empathetic -- and if you compound that over years, or generations, who knows? We often focus (rightly) on the direct health harms of pharmaceuticals, but we should also consider these subtler psycho-social effects. Especially for a drug so many give to their children regularly ("Here, take this, you'll feel better" -- it's practically a reflex for some parents), one has to wonder how it shapes the emotional development of those kids over time.
In summary, acetaminophen is not the inert, benign substance we were led to believe. Biochemically, it can stress the antioxidant system; developmentally, it can derail hormone signals and brain connectivity; behaviorally, it can flatten affect and social emotions. It's truly a pharmacological wolf in sheep's clothing. We're only now seeing its fangs.
Policy Whiplash: From "Totally Safe" to "Use Caution" -- What Happens Next?
The forthcoming HHS report linking autism to Tylenol is not happening in a vacuum. It comes after years of advocacy, scientific debate, and yes, stonewalling by certain interests. Let's put this in context.
For decades, the FDA maintained a relatively blasé stance on acetaminophen in pregnancy. To this day, if you go on the FDA's website, you'll find statements to the effect that "current evidence is inconclusive" and that there's "no clear proof" Tylenol causes developmental issues. Back in January 2015, amidst rising chatter about autism links, the FDA did issue a warning of sorts: it advised that expectant mothers should be cautious when using acetaminophen, only taking it when necessary. However, in the same breath, the agency hedged that it had "not found clear evidence" of risk and was not recommending against use. So essentially: be careful, but it's still officially safe. That half-measure did little to change medical practice. Obstetricians, guided by ACOG, continued to routinely tell pregnant patients that Tylenol was perfectly fine for headaches, fever, etc., and that they should avoid NSAIDs like ibuprofen (which do have known risks in pregnancy). In fact, acetaminophen was often the only pain reliever formally recommended for use by pregnant women16. The result: well over 50% of pregnant women worldwide use acetaminophen at some point, and a sizable subset (perhaps 20% of pregnant women) use it frequently or for extended periods17.
The 2021 consensus statement by 91 scientists and health professionals was a major attempt to push back on this complacency. Published in a top endocrine journal, it sounded the alarm that prenatal acetaminophen might indeed be causing harm and urged that pregnant women be educated about the potential risks and advised to curb use. The response from mainstream medical authorities, however, was defensive. ACOG (along with the UK's NHS and others) basically said, "no new action needed, keep calm and carry on." ACOG's official statement basically argued that the consensus authors were unnecessarily scaring women and that Tylenol remained the safest choice for pain/fever in pregnancy (since untreated fever can also cause problems). They emphasized that correlation isn't causation, and cited the lack of a known mechanism and the possibility of confounders. Some commentators even framed the concerns as anti-pharmaceutical scaremongering.
One particularly telling episode: The Center for Accountability in Science (a corporate-aligned advocacy group) and certain "fact-checking" media outlets strongly criticized a pivotal 2016 Spanish study (by Jordi Júlvez et al.) that had found acetaminophen use during pregnancy was linked to higher rates of autism and ADHD in the resulting children². Rather than thoughtfully consider the finding, these groups published articles with titles like "Don't worry, Tylenol is safe" and insinuated that the researchers hadn't accounted for X or Y. Dr. Parker noted in his review that these critics often employed logically flawed arguments such as, "Well, everyone uses it, so it can't be that bad," or "One single study isn't perfect, so let's ignore it," instead of looking at the big picture of accumulating evidence3. This strategy succeeded for a while in keeping public concern at bay.
Now, however, the dam is breaking. With the head of HHS himself (RFK Jr.) publicly embracing the acetaminophen-autism link, we are seeing a remarkable about-face. It's not just about one report; it symbolizes a broader shift toward finally applying the precautionary principle in mainstream medicine. It also sets up some potential clashes. How will organizations like ACOG and the FDA react to being effectively contradicted by HHS leadership? Will they double down, or will we see updated guidelines acknowledging the risks?
Read my 2023 call to have Tylenol Banned Immediately due to Widespread Harms here.
We may not have to wait long to find out. Reportedly, the HHS document will also propose that certain interventions (like high-dose folinic acid, i.e. leucovorin) might help treat or mitigate autism symptoms. That suggests a proactive stance: identify causes and propose fixes. If Tylenol use in pregnancy is identified as one contributor to autism, logically the next step would be for public health agencies to issue strong warnings about it -- perhaps similar to the warnings about alcohol and smoking during pregnancy. We might see label changes on acetaminophen products, OBs including warnings in their first prenatal visits, etc. The HHS announcement could also influence the CDC's messaging, since the CDC tracks autism rates and could incorporate this risk factor into its materials.
Of course, not everyone is on board. Kenvue/Johnson & Johnson are still in PR defense mode. A Kenvue spokesperson, reacting to the news, reiterated that the company "continuously evaluates the science" and "continues to believe there is no causal link between acetaminophen use during pregnancy and autism." They also trotted out that "the FDA and leading medical organizations agree on the drug's safety when used as directed". This line is to be expected -- no corporation will preemptively admit their product might be harming babies unless absolutely forced. But it's worth noting: internal documents uncovered in litigation (see next section) indicate that J&J and other makers have been aware of the brewing science for some time. They could have acted responsibly by at least updating their labels to mention the existence of these studies. In 2019, a citizen petition was even filed to the FDA asking for a pregnancy warning on acetaminophen products, highlighting the consensus statement and recent studies. The FDA dragged its feet (as of 2023, they had not resolved the petition).
This is why HHS's move is so consequential. If the top health agency in the nation stakes a position that "Tylenol may cause autism," that gives cover to regulators and organizations to reverse course without as much fear of reputational damage. It's a signal that the taboo is lifted. I suspect we'll see, in the coming year, a lot of the folks who said "no evidence of harm" now shifting to "well, out of an abundance of caution, limit use." Fine -- as long as the message of caution does get out there. Thousands of families have already paid a devastating price for the decades of denial. Let's not add thousands more.
Legal Reckoning: Tylenol Lawsuits, J&J's Defense, and the Precautionary Shift
Another major factor that likely spurred HHS to act now is the pressure of litigation. When scientific warnings fail, often the courts become the venue for accountability. And indeed, Tylenol-autism lawsuits have exploded in the last few years. By 2023, thousands of families across the U.S. had filed suits alleging that prenatal acetaminophen exposure caused their child's autism or ADHD. These cases have been consolidated into a federal Multidistrict Litigation (MDL) in the U.S. District Court for the Southern District of New York -- effectively a giant combined proceeding to handle all the pre-trial issues collectively. The MDL, overseen by Judge Denise Cote, includes claims not just against manufacturers (like J&J's subsidiary McNeil, which made Tylenol) but also against major retailers like Walmart, CVS, Walgreens, Costco, etc.. Why retailers? Because they sold store-brand acetaminophen and marketed Tylenol products as "safe for use during pregnancy" without any warning labels, thus arguably misleading consumers. It's an unusual twist -- holding retailers liable for an over-the-counter drug's risks -- but it reflects the breadth of this alleged corporate failure. Everyone in the chain, from drug maker to point-of-sale, effectively assured pregnant women that Tylenol was harmless, and the lawsuits claim that assurance was false and negligent.
As of mid-2025, more than 3,000 cases are formally docketed in MDL 3043, with thousands more pending review, making it one of the largest active product liability dockets in the U.S.
Johnson & Johnson, of course, has been fighting tooth and nail to avoid accountability. In 2023, J&J employed a "rare legal challenge" by filing a motion for an interlocutory appeal -- essentially asking an appellate court to review an issue before the trial has concluded. They did this after Judge Cote denied J&J's motion to dismiss the lawsuits on preemption grounds. J&J had argued that because Tylenol is regulated by the FDA (under an OTC monograph) and the FDA didn't require a pregnancy neurodevelopmental warning, no state court or jury can punish them for not having such a warning (federal law would preempt state failure-to-warn claims). The judge wasn't convinced. In April 2023, she ruled that "nothing in the federal rules and regulations actually prevented J&J from adding a warning to Tylenol about the risks of in utero exposure." In other words, J&J always had the ability to update its label if it wanted to alert customers -- the FDA wouldn't have stood in the way (especially not if presented with strong evidence). This is a crucial point: companies often hide behind the FDA, saying "we can't change labels without permission." But in the case of an OTC monograph, they could petition to add warnings. They didn't.
Judge Cote's rejection of J&J's preemption argument is precedent-setting: it confirms that OTC drug makers cannot hide behind the FDA's silence when mounting evidence calls for stronger warnings.
J&J's attempt to pause the litigation via interlocutory appeal was widely seen by legal observers as a long shot. One legal expert noted that the court is "unlikely to approve the appeal, as it would halt litigation that the judge is evidently determined to expedite." Sure enough, as of this writing, the MDL is charging forward. The judge has set an aggressive schedule for bellwether trials -- a handful of representative cases that will be tried first to gauge how juries respond to the evidence. Currently, only about 124 cases have been fully integrated into the MDL (those cleared initial hurdles), but thousands more sit in the wings, awaiting outcomes of certain Daubert hearings (where the admissibility of scientific expert testimony is decided). It's conceivable that if the plaintiffs start winning jury verdicts in these early cases, J&J and other defendants will feel pressure to settle the remainder en masse -- which could mean multi-billion dollar payoutsand, just as importantly, warning labels or product reformulations as part of settlement terms.
Interestingly, Judge Cote has reached out to the FDA for input -- she formally asked the FDA to weigh in on whether a warning about prenatal use should be added to acetaminophen products. The FDA has not yet given a substantive response (one reason being that such a statement could influence the litigation or be seen as taking sides). But if HHS (which oversees FDA) is now saying "yes, there is a link," that could prompt the FDA to finally act. One could envision the FDA moving to require a label warning such as: "If you are pregnant, consult your physician before using acetaminophen. Prolonged use during pregnancy may affect fetal development." Even a fairly mild warning would be a sea change from the current scenario of silence.
It's worth noting that Johnson & Johnson recently spun off Kenvue (which includes the Tylenol brand) in what some see as a strategy to protect J&J's core business from consumer health liabilities. Kenvue, as a separate company, inherits the Tylenol legal mess. The stock plunge we saw last week -- wiping out billions in market cap -- will surely not be the last shock if these cases move forward and more damning evidence emerges in discovery. Observers note that J&J's spin-off of Kenvue, which now carries Tylenol's liabilities, may function as a firewall strategy akin to the 'Texas two-step' bankruptcy maneuvers J&J attempted in the talc litigation.
What kind of evidence might come out in court? Perhaps internal emails or memos where company scientists discuss the emerging autism link data. Maybe correspondence with the FDA or NIH. We already have some public evidence: for example, in 2009 the FDA's own scientists expressed concern about infant acetaminophen being used routinely with vaccines, after studies in animals hinted it could worsen vaccine adverse reactions. Those concerns went nowhere at the time. If such documents surface, showing that the industry knew of red flags but opted to not warn consumers, it will significantly bolster the plaintiffs' case (and moral high ground).
If Parker's in-silico modeling and biomarker-based evidence withstand Daubert scrutiny, juries will be presented with a unified story: that industry knew signals of harm existed, ignored them, and continued to market Tylenol as universally safe.
From a legal perspective, HHS publicly affirming the Tylenol-autism link could be a boon for plaintiffs. Juries tend to lend weight to government pronouncements. Defendants will no doubt protest that HHS (under RFK Jr.) is politicized or out of step with mainstream science, but a government report is still a government report. It might also pave the way for a global settlement if J&J/Kenvue see the writing on the wall.
Legal momentum almost certainly influenced HHS's decision to acknowledge a Tylenol–autism link, providing political cover for regulators while strengthening the plaintiffs' position in court.
The litigation has also forced a broader discussion of corporate responsibility. Should drug companies be allowed to peddle a product to pregnant women for generations without ever having formally tested its effects on the fetus? (Acetaminophen was grandfathered in and never underwent modern FDA approval studies for pregnancy safety; it's Category B mainly by convention.) The fact that **the primary manufacturer privately acknowledged that Tylenol "has never been shown to be safe for brain development when used during pregnancy or in childhood"**18 is absolutely damning. Dr. Parker highlighted that admission in 2018 -- it came from a legal brief where the company essentially said "no one ever checked neurodevelopment in our safety studies." To me, that speaks volumes. We, as a society, assumed safety where there was none demonstrated. We are now living with the consequences.
This acknowledgment dovetails with Parker's broader critique: not only has Tylenol never been proven safe for fetal neurodevelopment, but methodological flaws in recent 'reassuring' studies risk compounding decades of regulatory negligence.
What Should Parents and Doctors Do Now?
In the wake of this news, I'm sure many reading this (especially expectant parents or those planning to have children) are wondering: What do we do? Have we been unknowingly putting our babies at risk? And if so, how can we protect them going forward?
First, let me say this plainly: If you are pregnant (or a caregiver to a young child), you should treat acetaminophen as a medication that carries real risks, not as a benign routine aid. This doesn't mean "never take it under any circumstance." It means the threshold for use should be high. The new consensus -- even among many cautious academic scientists -- is that acetaminophen should be used sparingly in pregnancy, only when absolutely necessary8. The authors of the 2025 Navigation Guide review explicitly recommend *"judicious acetaminophen use -- [the] lowest effective dose, [the] shortest duration -- under medical guidance, tailored to individual risk-benefit assessments"*8. In plain English: if you're expecting and in pain or have a fever, try to find alternative methods to manage it first. Non-drug approaches like rest, hydration, a cool compress for fever, or perhaps approved supplements (under a practitioner's guidance) should be considered. If you truly need relief -- for instance, a high fever in pregnancy can be dangerous, so bringing it down with with alternative methods with the assistance of a medical professional is essential. You can explore evidence-based, alternative approaches on our Fever database here.
The same goes for infants and children: don't reflexively give antipyretics for every mild fever or fussiness. Fever, unless dangerously high, is a natural immune response; a temperature of 100-101°F in a toddler is not automatically an emergency that needs medicating. Many pediatricians in other countries advise letting a moderate fever run its course, as long as the child is hydrated and not in extreme discomfort. If a fever becomes high enough to risk febrile seizure or the child is in pain, by all means treat it -- but again, dose carefully and avoid serial dosing for days.
For healthcare providers, this paradigm shift means changing the advice you give. OB/GYNs should start discussing acetaminophen's potential risks with their patients early in pregnancy. This can be done without causing panic -- just frame it as, "We have new evidence that suggests frequent Tylenol use might not be as safe as we thought. Let's try to limit it and explore other ways to keep you comfortable." Given that mainstream institutions (HHS, etc.) are now recognizing the link, doctors should feel less fear of going against guidelines. In fact, not updating patients at this point could expose providers to liability in the future ("Why didn't my doctor tell me about this?").
Pediatricians, too, should reconsider that age-old advice of pre-medicating babies with Tylenol before shots or handing out free acetaminophen samples to new parents "just in case." Instead, they should emphasize supportive care for mild fevers and pain -- like lukewarm baths, gentle rocking, and patience. If medication is needed, they might consider ibuprofen in babies over 6 months (which, while not risk-free, has not been linked to autism and does not deplete glutathione the way Tylenol does -- note that ibuprofen is contraindicated in late pregnancy, however, due to a different set of issues).
Let's also address a key point: Many pregnant women have been taking Tylenol under the assumption it was 100% safe. If you're reading this and you did so -- do not despair. Remember that the increased risks we're talking about, while significant on a population level, are still modest on an individual level. A 20-30% increase in relative risk means that if your baseline chance of having a child with ASD was, say, 1%, it might become ~1.3% if you took a lot of Tylenol. The vast majority of women who used acetaminophen will not have a child with autism or ADHD because of it. These disorders are multi-factorial; acetaminophen is likely one contributor among many (genetics, other toxic exposures, etc.). So if you did use some Tylenol, don't beat yourself up -- you were following prevailing medical advice. The best you can do now is focus on supporting your child's health and development proactively. There are many ways to bolster a child's neurodevelopment (healthy diet, minimizing further toxin exposures, early intervention if any delays appear, etc.). Knowledge is power going forward.
For those currently pregnant, you now have information your mother or grandmother didn't: exercise caution. Consider having a conversation with your healthcare provider about what to do if you get a fever or severe pain during pregnancy before it happens -- have a plan that doesn't default to Tylenol unless truly necessary. Some OBs are now recommending alternatives like acetaminophen combined with small doses of caffeine for headaches (since you can use less acetaminophen that way), or non-pharmacological interventions for back pain (e.g. prenatal yoga, physical therapy). Every situation is unique; the key is to treat Tylenol with respect, not as candy.
One more piece of practical advice: spread the word to other parents and parents-to-be. Many will not hear about this HHS report because these kinds of announcements often slip under the radar or get drowned in controversy. Share credible information (perhaps the Harvard press release⁸ or the consensus statement or even this article) with friends or family who are expecting. It's not about scaring anyone; it's about empowering informed choices. The worst-case scenario is that this news comes and goes and nothing changes at the grassroots level. We can't let that happen. We owe it to the next generation to apply what we've learned. As the authors of that 2021 consensus statement wrote, it would be a disservice to pregnant women to keep them in the dark about a potential risk this important19. Pregnant individuals have the right to make an informed decision about what they put in their bodies -- they may still choose to use Tylenol, but it should be a conscious choice, not an ignorant one.
A Turning Point for Accountability and Precaution
As I reflect on these developments, I feel a mix of anger, hope, and resolve. Anger, that it took this long and that so many families suffered while establishment medicine dragged its feet. Hope, that this could mark the beginning of a new era where environmental and pharmaceutical factors in children's health get taken seriously at the highest levels. And resolve, to continue our mission at GreenMedInfo: to bring real evidence-based information to light, especially on topics that threaten powerful interests and thus often get suppressed.
Robert F. Kennedy Jr., heading HHS, is certainly a polarizing figure, but one thing no one can deny is that he's willing to challenge entrenched narratives about public health. By tackling the Tylenol issue head on, he's doing something extraordinary that past HHS officials (many of whom later go work for pharma companies) likely wouldn't have done. This speaks to a broader potential policy shift toward precaution. If we accept that acetaminophen -- a drug used ubiquitously for over 70 years -- can have such grave unintended consequences, what other "accepted safe" exposures might be contributing to our epidemics of childhood chronic illness? RFK Jr. has hinted that the autism puzzle likely has multiple pieces ("certain interventions" in plural). Tylenol may be a big piece, but there are surely others (pesticides, other pharmaceuticals, nutritional deficiencies, etc.). Identifying and eliminating those could finally stem the tide of ever-increasing developmental disorders. We're talking about potentially reclaiming the health of future generations.
Meanwhile, the Tylenol saga should serve as a cautionary tale to the medical community and regulators. Complacency and groupthink can be devastating. Acetaminophen was first introduced in the 1950s. It became over-the-counter in 1959. It wasn't until the late 2000s that serious questions about neurodevelopment started getting aired, and even then they were marginalized. Imagine if we had acted in, say, 2010 -- put a warning on then, curbed use -- perhaps tens of thousands of cases of ASD/ADHD could have been prevented. Instead, autism rates went from 1 in 150 (2000) to 1 in 36 (2020), and we're still scratching our heads as to why. It's time to admit that "coincidence" is not an explanation. It's time to hold these companies accountable and demand real proof of safety for products that we give to pregnant women and babies.
I'll end with this thought: when thalidomide was found to cause birth defects in the 1960s, it led to a revolution in drug regulation and the establishment of stricter safety testing (especially in pregnancy). We are now, I believe, on the cusp of another such inflection point. Acetaminophen's story could very well rewrite the rules on what is required to declare something "safe for pregnancy/children." At the very least, it's going to force doctors to rethink the casualness with which they hand out OTC advice. And for parents, it's a wake-up call that we have to be our own advocates. The authorities and experts don't always have it right -- sometimes far from it. Trust your intuition, stay informed, and don't be afraid to question the consensus when your child's health is on the line.
The coming months will be fascinating. Will we see Tylenol bottles with warning stickers by year's end? Will ACOG issue a revised statement? How will the pending lawsuits resolve -- a huge settlement, or dragged-out trials? We'll be following all of it closely here at GreenMedInfo, just as we have for years. And you can bet we'll continue to shine a light on these issues, no matter how uncomfortable it makes the powers that be. Because ultimately, our loyalty is to the truth and to the well-being of our readers and their families.
Stay tuned, stay informed, and as always, take care of your health -- no one else can do it for you.
Learn more by reading PART II below.
Tylenol and Autism, Part II: The Swedish Study That Got It Wrong
Sayer Ji · Sep 7
Part I: Breaking: Government Finally Admits Tylenol-Autism Link After Years of Corporate Cover-Up
Looking for natural alternatives to Pain? You can consult hundreds of studies and dozens of translational articles on natural, evidence-based alternatives like tart cherry, lavender extract, noni, and turmeric on our Pain database below.
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References
1. Baletti, Brenda. "U.S. Health Secretary Robert F. Kennedy Jr. Plans to Link Autism to Tylenol Use During Pregnancy, WSJ Reports." The Defender (Children's Health Defense), September 5, 2025.
2. Cáceres, Marco. "Acetaminophen Linked to Autism and Other Neurological Disorders in Children." The Vaccine Reaction, October 6, 2022. Reposted on GreenMedInfo. www.greenmedinfo.com/blog/tylenol-damages-brains-children-research-reveals
3. Parker, William, Ph.D. "Tylenol Damages The Brains of Children, Research Reveals." GreenMedInfo, December 22, 2018. www.greenmedinfo.com/blog/tylenol-damages-brains-children-research-reveals
4. Ibid.
5. Ibid.
6. Ibid.
7. Ibid.
8. Lau, Jay. "Using Acetaminophen During Pregnancy May Increase Children's Autism and ADHD Risk." Harvard T.H. Chan School of Public Health News, August 20, 2025. https://hsph.harvard.edu/news/using-acetaminophen-during-pregnancy-may-increase-childrens-autism-and-adhd-risk/
9. Prada, Diddier, et al. "Evaluation of the Evidence on Acetaminophen Use and Neurodevelopmental Disorders Using the Navigation Guide Methodology." Environmental Health 24, Article no. 56 (2025). https://ehjournal.biomedcentral.com/articles/10.1186/s12940-025-01208-0
10. Ibid.
11. Parker, "Tylenol Damages The Brains of Children."
12. Ibid.
13. Kristensen, David Møbjerg, et al. "Prolonged exposure to acetaminophen during pregnancy reduces testosterone production by the human fetal testis." Science Translational Medicine 9, no. 388 (2017). https://pmc.ncbi.nlm.nih.gov/articles/PMC5451610/
14. Ibid.
15. Parker, "Tylenol Damages The Brains of Children."
16. Prada et al., "Evaluation of the Evidence on Acetaminophen Use."
17. Ibid.
18. Parker, "Tylenol Damages The Brains of Children."
19. Bauer, Ann Z., Shanna H. Swan, David Kriebel, et al. "Paracetamol Use During Pregnancy -- A Call for Precautionary Action." Nature Reviews Endocrinology 17 (October 2021): 757-766.
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