On Sept. 22, the Trump administration announced that acetaminophen — commonly known by the brand name Tylenol — can increase the risk of neurological conditions, such as autism spectrum disorder and attention-deficit/hyperactivity disorder.
Three public health researchers at Brown criticized the announcement in interviews with The Herald, saying that little scientific evidence shows acetaminophen causes autism.
“The best evidence suggests that there’s no connection between Tylenol and autism, and that what happened here was really an act of politics,” Ashish Jha, the dean of the School of Public Health, said in an interview with The Herald.
Studies have found the prevalence of autism has increased by over 175% from 2011 to 2022 in the United States. In April, U.S. Secretary of Health and Human Services Robert F. Kennedy Jr. declared that he would find the cause of autism by September.
“He needed to deliver a political win, and so he picked Tylenol, because there’s some very, very shaky poor quality evidence behind it,” Jha said.
Kenvue, Tylenol’s parent company, released a statement stating that “sound science clearly shows that taking acetaminophen does not cause autism.”
“We strongly disagree with allegations that it does and are deeply concerned about the health risks and confusion this poses for expecting mothers and parents,” the statement continued.
HHS could not be reached for comment.
Joseph Braun, a professor of epidemiology who researches risk factors during pregnancy, wrote in an email to The Herald that it is unclear “why acetaminophen was singled out when there are other potential causes or protective factors for autism that have a strong evidence base.”
“Numerous well-conducted studies show that prenatal air pollution exposure can increase the risk of ASD and others show that folic acid supplementation during pregnancy could reduce the risk,” he wrote.
Jha added that the announcement is also bound “to do enormous harm” to pregnant women themselves. Currently, acetaminophen is the only over-the-counter drug that is approved by the U.S. Food and Drug Administration to mitigate high fevers during pregnancy.
Jha, Braun and Alyssa Bilinski — an assistant professor of health policy, health services, policy and practice and biostatistics — all warned against the dangers associated with a high fever during pregnancy.
“Acetaminophen currently is really the first line go-to medication during pregnancy for fever and pain relief,” Bilinski explained. The drug can also be useful to determine whether a headache or fever is responsive to medication. It could also serve as a precursor to a more dangerous disease such as preeclampsia, which “could be potentially life threatening” without treatment, she added.
Jha noted that “there are real, well-documented risks of not treating a high fever during pregnancy” and there are “no other choices” for medications that reduce fevers for pregnant women.
“It’s going to put a lot of women in very difficult circumstances,” he added.
Bilinski explained that in the past couple of years, evidence disputing the link between acetaminophen and autism has gotten stronger, especially using sibling controls.
One popular research technique in pregnancy studies “is to look at outcomes comparing siblings who were and were not exposed to medication,” she said. “This allows researchers to control for other specific factors, things like a genetic predisposition to autism.”
Bilinski mentioned one such 2024 study that used sibling cohorts and found no link between acetaminophen and some neurological disorders, including autism.
Both Bilinski and Braun added that studies that do suggest a link often do not account for confounding factors, complicating the conclusions.
“One of the major threats to many individual studies, and thus the overall conclusion, is that the reason for taking acetaminophen during pregnancy may be the cause of autism,” Braun wrote.
“When you’re better able to account for the sort of factors that co-occur with acetaminophen use through sibling studies,” Bilinski added, “we do not see a link.”
Correction: This article has been updated to better reflect the body of research about the co-factors that could contribute to the studies' scientific findings.
Claire Song is a university news and science & research editor for The Herald. She is a sophomore from California studying Applied Math-Biology. She likes to drink boba in her free time.
