Scientists find no link between Tylenol and autism, again, after Trump’s warning

Similar structure to siblings

The researchers conducted a sibling matching study, comparing autism and ADHD among siblings, some who were exposed to acetaminophen in utero and others who were not. This research design helps account for unmeasured family factors that influence the likelihood of conditions, particularly genetics and environmental factors. The autism analysis included more than 124,000 sibling-matched children, and the attention-deficit/hyperactivity disorder (ADHD) analysis included a group of more than 97,000 sibling-matched children.

The researchers did not see a link between prenatal acetaminophen use and any complications. It did not matter how much acetaminophen was taken, when it was taken during the pregnancy (in the third trimester), how often it was taken, or how old the woman was at the time. There was no association between acetaminophen and autism or ADHD.

Interestingly, there was a link when the researchers abandoned the comparative design of his siblings and instead compared the acetaminophen-exposed and unknown children, which is a finding that has come in other studies. But when the researchers looked at the “adverse effects” and compared children whose mothers took acetaminophen before pregnancy or just after giving birth to mothers who didn’t use the painkiller, they also saw an association—one that was “naturally impossible.”

“Together, these findings suggest that the positive sign observed in both the controls and the negative controls reflect family residuals, rather than a true effect of paracetamol exposure,” the researchers concluded.

The finding that there is no association between the use of acetaminophen during pregnancy and neurodevelopmental disorders in children was also found in a large comparative study of its siblings. Sweden in 2024 and Japan in 2025.