Acetaminophen Use During Pregnancy May Increase Children’s Autism and ADHD Risk, Study Finds

Acetaminophen, commonly sold under the brand name Tylenol and many others, has been considered the safest painkiller for women who are pregnant.

Tylenol brand pain relief medicine on display at the Safeway store in Wheaton, Md., on Feb. 13, 2015. Gary Cameron/Reuters

A recent study found that acetaminophen usage during pregnancy may be associated with a higher likelihood of the child developing autism spectrum disorder or ADHD later on in their childhood.

Acetaminophen, commonly sold under the brand name Tylenol and many others, has been considered the safest painkiller for pregnant women to manage fever, headache, and other pain. It’s also called paracetamol in other countries, including the United Kingdom.

But in the study published earlier this month, researchers led by Andrea Baccarelli of Harvard University found that when children are exposed to the drug during pregnancy “they may be more likely to develop neurodevelopmental disorders (NDDs) including autism and ADHD,” a university press release said on Aug. 20.

Analyzing the results of 46 studies on the painkiller that represents data from 100,000 participants, the researchers looked at a possible connection between pregnant women taking acetaminophen and neurodevelopmental disorders such as autism and ADHD, also known as attention-deficit/hyperactivity disorder.

Their analysis, according to the study’s conclusion, “identified studies that found a statistically significant increased risk of NDDs such as ADHD and [autism spectrum disorder] from prenatal acetaminophen exposure, as well as a smaller number of studies that did not find such an association.”

The study, published on Aug. 13 in the BMC Environmental Health journal, did not show that acetaminophen can directly cause autism and ADHD, but the researchers involved in the paper raised concerns about current clinical guidelines around administering the painkiller for pregnant women.

“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, an assistant professor at the Icahn School of Medicine at Mount Sinai who was involved in the study, in a statement. “Given the widespread use of this medication, even a small increase in risk could have major public health implications.”

Prada added that “pregnant women should not stop taking medication without consulting their doctors,” noting that ”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.”

The paper adds to a body of research that has been collected about acetaminophen. In 2019, a study from Johns Hopkins University that analyzed umbilical cord blood samples found an association between newborns with the highest exposure to the painkiller and ADHD or autism diagnoses during childhood.

Researchers found that they were “roughly three times more likely to be diagnosed” with either neurological condition later in their childhood when compared with children who were exposed to the lowest levels of acetaminophen, said the university at the time.

But last year, a study published in the Journal of the American Medical Association and funded by the U.S. National Institutes of Health found that there was no association between pregnant women taking acetaminophen and a higher risk of autism. The researchers analyzed 2.5 million Swedish children who were born between 1995 and 2019.

They further found that in previous analyses, there may have been other potential factors that may have distorted the results showing a link between acetaminophen and NDDs, said the paper.

Findings from studies showing a connection between acetaminophen and autism or ADHD has fueled lawsuits over the years against companies that manufacture drugs that contain acetaminophen. In 2023, a judge issued a ruling that effectively ended hundreds of lawsuits against Johnson & Johnson’s Tylenol.

“Instead, the unstructured approach adopted by the plaintiffs’ experts permitted cherry-picking, allowed a results-driven analysis, and obscured the complexities, inconsistencies, and weaknesses in the underlying data,” U.S. District Judge Denise Cote in Manhattan wrote.

On its website, the Food and Drug Administration says that the agency is aware of studies questioning the safety of acetaminophen usage while pregnant.

“Because of this uncertainty, the use of pain medicines during pregnancy should be carefully considered. We urge pregnant women to always discuss all medicines with their health care professionals before using them,” the agency said.