Scientists are warning that one of the most trusted painkillers used in pregnancy may not be as safe as once believed.
A sweeping review of studies finds links between prenatal acetaminophen exposure and higher risks of autism and ADHD in children. The medication crosses the placenta and may interfere with brain development, raising urgent questions about clinical guidelines.
Acetaminophen in Pregnancy Linked to Neurodevelopmental Risks
Scientists at the Icahn School of Medicine at Mount Sinai report that children exposed to acetaminophen before birth may face a greater chance of developing neurodevelopmental conditions such as autism spectrum disorder and attention-deficit/hyperactivity disorder (ADHD). Their findings, published in BMC Environmental Health, mark the first time that the Navigation Guide methodology has been applied to thoroughly assess the quality and reliability of the research on this subject.
Acetaminophen (commonly sold as Tylenol® in the United States and Canada, and known as paracetamol elsewhere) is the most widely used non-prescription treatment for pain and fever during pregnancy, taken by more than half of expectant mothers worldwide. For decades, it has been viewed as the safest option for relief from headaches, fever, and general pain. However, the Mount Sinai team’s review of 46 studies, which together involved over 100,000 participants from multiple countries, challenges this long-standing belief and highlights the importance of caution and additional investigation.
Gold-Standard Review Methodology Applied
The research team relied on the Navigation Guide Systematic Review, a leading framework used in environmental health. This method enables scientists to systematically evaluate each study, rating potential sources of bias such as incomplete data or selective reporting, while also weighing the overall strength and consistency of the evidence.
“Our findings show that higher-quality studies are more likely to show a link between prenatal acetaminophen exposure and increased risks of autism and ADHD,” said Diddier Prada, MD, PhD, Assistant Professor of Population Health Science and Policy, and Environmental Medicine and Climate Science, at the Icahn School of Medicine at Mount Sinai. “Given the widespread use of this medication, even a small increase in risk could have major public health implications.”
Possible Biological Mechanisms Behind the Link
The paper also explores biological mechanisms that could explain the association between acetaminophen use and these disorders. Acetaminophen is known to cross the placental barrier and may trigger oxidative stress, disrupt hormones, and cause epigenetic changes that interfere with fetal brain development.
While the study does not show that acetaminophen directly causes neurodevelopmental disorders, the research team’s findings strengthen the evidence for a connection and raise concerns about current clinical practices.
Call for Updated Guidelines and Safer Alternatives
The researchers call for cautious, time-limited use of acetaminophen during pregnancy under medical supervision; updated clinical guidelines to better balance the benefits and risks; and further research to confirm these findings and identify safer alternatives for managing pain and fever in expectant mothers.
“Pregnant women should not stop taking medication without consulting their doctors,” Dr. Prada emphasized. “Untreated pain or fever can also harm the baby. Our study highlights the importance of discussing the safest approach with health care providers and considering non-drug options whenever possible.”
Rising Autism and ADHD Rates Add Urgency
With diagnoses of autism and ADHD increasing worldwide, these findings have significant implications for public health policy, clinical guidelines, and patient education. The study also highlights the urgent need for pharmaceutical innovation to provide safer alternatives for pregnant women.
Reference: “Evaluation of the evidence on acetaminophen use and neurodevelopmental disorders using the Navigation Guide methodology” by Diddier Prada, Beate Ritz, Ann Z. Bauer and Andrea A. Baccarelli, 14 August 2025, Environmental Health.
DOI: 10.1186/s12940-025-01208-0
The study was conducted in collaboration with the University of California, Los Angeles; University of Massachusetts Lowell; and Harvard T.H. Chan School of Public Health.
Funding for this study was provided by the National Cancer Institute (U54CA267776), the National Institute of Environmental Health Sciences (R35ES031688), and the National Institute on Aging (U01AG088684).
Important: These findings indicate a correlation, not definitive proof of causation. The medical community remains divided, and further research is needed. Always seek guidance from your healthcare professional before altering or discontinuing any treatment.
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6 Comments
Amazing. Autism was first recorded in 1943. Acetaminophen aka Tylenol wasn’t sold until 1955. Quit bowing to fascism.
Your politics may be clouding your judgment.
Tylenol is indeed a brand of acetaminophen that was first sold in 1955. However, acetaminophen was first synthesized in 1878 and sold as a pain and fever treatment since 1893.
I’m curious to know more specific details on what chemicals in Tylenol actually affect the brain. Maybe it’s still being studied out, but I can’t wait to see more info other than “there may be a link.”
Also, I’m wondering if the age of the parents was considered during these studies?
Yes, it appears maternal age and other key confounders were considered overall. You can see more in the actual study’s “discussion” section, and the sections leading up to it regarding risk-of-bias assessment. “Studies were rated as higher risk of bias (score of 3 or 4) if they lacked adjustment for key confounders, such as maternal age, chronic illness, socioeconomic status, smoking, alcohol use, or clinical indications for acetaminophen use (e.g., fever or infection).” // “Our Navigation Guide-based evaluation of the existing literature showed a strong, consistent association between prenatal acetaminophen exposure and ADHD/ASD/other NDDs. These studies were controlled for multiple potential confounders that might have plausibly explained the associations, yet the associations persisted.”
This isn’t about politics. It’s about confusion. The ACOG is filled with physicians who monitor drug safety in pregnancy and care passionately about this topic and spend all day every day working with pregnant women and delivering babies for years and years of their lives, monitoring outcomes, watching for trends, updating medication safety guidelines frequently when new information comes to light. Yet somehow all of these physicians missed this or somehow covered it up? It doesn’t make sense.
The reason pregnant women take acetaminophen is to reduce fever. Has this study looked at the role of fever and the illnesses that lead to fever as a possible causes for poor neurodevelopmental outcomes and children. This is the prime example of correlation not causation.