Competing Papers Diverge on Possible Link Between Tylenol and Autism

One review says evidence shows acetaminophen triggers autism, while the other says there is no clear link.

Tylenol and acetaminophen tablets in a CVS store, in a file photograph. Ronaldo Schemidt/AFP via Getty Images

Two new papers diverge on whether the active ingredient in Tylenol, when used by pregnant women, leads to the development of autism or attention deficit/hyperactivity disorder (ADHD) in children.

An umbrella review published on Nov. 10 analyzed nine systematic reviews and concluded that “existing evidence does not clearly link maternal paracetamol use during pregnancy with autism or ADHD in offspring.”

Paracetamol, also known as acetaminophen, is the active ingredient in the pain reliever Tylenol.

A separate paper said that available evidence “shows that exposure of susceptible babies and children to acetaminophen (paracetamol) triggers many if not most cases of autism spectrum disorder, and that oxidative stress causes susceptibility.” The paper was published by the Journal of the Academy of Public Health on Oct. 26.

Both papers came after health officials said that there was enough evidence suggesting that maternal acetaminophen use results in autism that they were issuing a new warning about pregnant women taking Tylenol or other drugs containing the ingredient.

“We now have data we cannot ignore,” Dr. Marty Makary, the Food and Drug Administration’s commissioner, said during a briefing in September.

A spokesperson for Kenvue, which makes Tylenol, recently told The Epoch Times in an email, “We stand firmly with the global medical community that acknowledges the safety of acetaminophen.”

Umbrella Review

Systematic reviews look at available research on a topic. The umbrella review, conducted by researchers in the United Kingdom, Australia, and Spain, analyzed nine reviews on maternal acetaminophen intake that included 40 studies, including six studies dealing with autism.

The researchers said that most of the reviews failed to meet certain criteria, such as not including a list of studies they excluded with reasons for the exclusions.

While all reviews found a positive association between pregnant women taking acetaminophen and children developing neurodevelopmental problems, seven of the reviews cautioned that they could not establish that acetaminophen use led to the problems. Two of the reviews adjusted for confounding by analyzing siblings. Those reviews initially pointed to small, positive associations, but including siblings “shifted the estimates towards a null effect,” the researchers said.

They concluded that the quality of the reviews was low and that the current evidence “is insufficient to definitively link in utero exposure to paracetamol with autism and ADHD in childhood.”

The authors declared funding from several institutions, including the Instituto de Salud Carlos III, and no competing interests.

Other Paper

Researchers in the other paper previously concluded that pregnant women using acetaminophen caused neurodevelopmental issues, including autism.

In the new paper, they said they systematically analyzed papers available through PubMed, a library maintained by the National Institutes of Health, that dealt with acetaminophen and autism to figure out why those conclusions are not widely accepted by doctors.

Sixty-four papers published from 2008 to 2025 were identified. During that 18-year timeframe, no shift in opinions or conclusions on the topic occurred, the researchers said.

The authors said that one of the problems was a mishandling of evidence, including the dismissal of some evidence, such as results from parental surveys, even though surveys are commonly used in studying medical issues.

“This systematic review of the literature suggests that several factors contribute to years of failure to halt the ongoing adverse impact of acetaminophen on neurodevelopment,” the authors stated.

“Mishandling and misinterpretation of data are pervasive, particularly errors involving statistical analysis, limiting consideration of acetaminophen-mediated neurodevelopmental injury to some fraction of the total window of sensitivity to injury, and considering evidence from limited fields of research when drawing conclusions. Unfair criticisms of some studies also apparently play a role in the problem.”

The authors declared funding from WPLab, a nonprofit based in North Carolina, and no conflicts of interest.