Researchers have long been trying to pinpoint the specific factors that play a role in the development of autism spectrum disorder as diagnosis rates skyrocket.
Robert F. Kennedy Jr.’s Department of Health and Human Services is planning to release a report this month that will link prenatal exposure to acetaminophen — a popular pain reliever most commonly known by the brand name Tylenol — and certain vitamin deficiencies to autism, The Wall Street Journal reported.
“We are using gold-standard science to get to the bottom of America’s unprecedented rise in autism rates,” an HHS spokesperson told The Post Friday after the WSJ published its article.
“Until we release the final report, any claims about its contents are nothing more than speculation.”
In the meantime, here’s a look at the research into the use of acetaminophen and autism.
What is autism?
It’s a complex disorder that affects brain development, resulting in differences in social communication as well as repetitive behaviors and focused interests.
According to federal estimates, autism affects one in 31 US children.
And these numbers are on the rise, with diagnoses in the US jumping 175% between 2011 and 2022.
Extensive evidence suggests that interactions between genetic and environmental factors are key to the development of autism.
These factors may include advanced parental age, infections during pregnancy, birth complications, a premature baby or one with lower-than-expected fetal growth or use of certain medications while pregnant.
What is acetaminophen?
It’s an over-the-counter medication designed to relieve mild to moderate pain and reduce fever, though scientists aren’t exactly sure how it works.
It’s most famously sold as Tylenol. It’s also known as paracetamol outside the US. Acetaminophen is widely used to treat maternal fever and pain.
What do the studies say?
A 2024 study of nearly 2.5 million Swedish children found no causal link between prenatal use of acetaminophen and neurodevelopmental disorders like autism or attention deficit hyperactivity disorder (ADHD).
The Icahn School of Medicine at Mount Sinai led a 2025 analysis of 46 studies that did identify a potential link to an increased risk of these conditions.
The researchers warned that acetaminophen may trigger oxidative stress, interfere with hormones and cause genetic changes that disturb fetal brain development, but cautioned that more research is needed to establish a causal relationship.
“We recommend judicious acetaminophen use — lowest effective dose, shortest duration — under medical guidance, tailored to individual risk-benefit assessments, rather than a broad limitation,” the researchers wrote last month in BMC Environmental Health.
One theory is that any potential link may be due to the underlying conditions that caused the mother to take the acetaminophen.
The American College of Obstetricians and Gynecologists (ACOG) maintains that acetaminophen is safe for pregnant women, though it advises all expectant mothers to consult with their doctor before taking any medication.
For its part, a spokesperson for Tylenol-maker Kenvue told the WSJ that it “continues to believe there is no causal link between acetaminophen use during pregnancy and autism.”
Kenvue’s shares fell more than 14% on Friday after the WSJ published its report.
Many Tylenol-related lawsuits claiming links to autism have been dismissed due to a lack of credible scientific evidence supporting the claims.
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