President Donald Trump and Health and Human Services Secretary Robert F Kennedy Jr. announced a link between autism and the use of the pain reliever acetaminophen during pregnancy on Monday.
Ahead of the announcement, Trump said he believed the drug was “a very big factor” in causing autism and also expressed concern about shots given to children, saying they “get these massive vaccines like you’d give to a horse.”
Kennedy, who has long spread vaccine misinformation, has previously pushed a discredited theory that routine childhood vaccines were the cause of autism. After becoming HHS secretary, he pledged to determine the causes of autism by September, calling it an “epidemic.”
Kennedy has recently claimed that “interventions to improve health” were “almost certainly” responsible for autism, and alleged that many autistic children had been “fully functional” before they “regressed.”
However, decades of research has shown no direct connection between autism and acetaminophen, which is commonly known by the brand name Tylenol.
“Advising pregnant women not to take Tylenol is simply highly irresponsible,” Dr. Helen Tager-Flusberg, professor emerita at Boston University and head of the Coalition of Autism Scientists, told The Independent.
“I would say this is the concern of the entire autism community. Scientists, individuals with autism, parents who have an autistic child, we’re all concerned that here’s a major announcement with significant implications that is simply not tied to the reality of the scientific evidence itself.”
What happened during RFK Jr’s announcement?
The Department of Health and Human Services linked taking acetaminophen during pregnancy to children developing autism.
Officials recommended that acetaminophen only be used to tackle high fever in pregnant woman, a move that was first reported by The Washington Post.
They said that the Food and Drug Administration would issue a physician’s notice about the risk of acetaminophen during pregnancy and begin the process to initiate a safety label change.
In response, Kenvue Inc., the American company that makes Tylenol, said that over a decade of “rigorous research” confirmed “there is no credible evidence linking acetaminophen to autism.”
HHS also advised that people take the cancer and anemia drug leucovorin to address symptoms of autism. Leucovorin is usually prescribed to counteract the side effects of medications and treat vitamin B deficiency.
How much research has been done on autism and acetaminophen – and what does it say?
A Harvard and Mount Sinai review, published in August, found that using acetaminophen may be linked to an increased risk of autism and ADHD. It looked at results from 46 past studies including data from more than 100,000 participants.
“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,” Dr. Diddier Prada, an assistant professor at Mount Sinai, said.
However, the authors cautioned that their review does not show that acetaminophen directly causes neuro-developmental disorders and did not recommend stopping its use altogether.
A 2024 study, from Drexel University, found no link between acetaminophen and autism following the drug’s use in pregnancy when looking at data from 2.4 million children over the past 25 years.
Dr. Brian Lee, who was part of the Drexel research team, said that “the causal effect on autism and ADHD, specifically, is not present”– meaning the drug has not been found to cause autism.
He added: “The weight of evidence for air pollution and autism is certainly a lot stronger than for acetaminophen and autism but I don’t see anyone in the administration rushing out to say we should limit air pollution.”
Lee also told The Independent that he would not recommend leucovorin as a treatment for autism yet, and that more research needs to be done to recommend the drug.
“We need large scale, randomized, controlled trials, which will be impossible to do because this is something that you can buy on Amazon,” Tager-Flusberg added.
Why are there more cases of autism spectrum disorder now?
Autism cases have been rising in the U.S. for decades increasing from one in 150 children in the early 2000s to one in 31 today, according to federal health officials.
Experts say this is because more children are being diagnosed with the disorder. In the 1990s, only the children with the most profound symptoms were considered to have autism.
Now, more than five million Americans are autistic, including 1.5 million children.
A single cause of autism has not been determined, but genetics, environmental factors, and a mother’s health during pregnancy are all believed to play a role, according to the Cleveland Clinic.
Is it safe for pregnant women to use Tylenol in pregnancy?
Experts told The Independent that it is. Used by more than half of pregnant women worldwide, Tylenol is the safest known drug to take during pregnancy for problems like fever and pain, doctors agree.
Leaving fever and pain untreated has been linked to preterm birth and miscarriage.
“Because we know that women take Tylenol because they have a fever or an infection, and those we do know contribute some risk during the early months of pregnancy,” Tager-Flusberg, professor emerita at Boston University, said.
Dr. Jake Scott, an infectious diseases specialist at Stanford Medicine, called the president’s claims about vaccines “completely wrong.”
“When he compares vaccinating a baby to ‘shooting up a horse,’ he fundamentally misunderstands how vaccines work,” said Scott.
Scott and Dr. Dr. Paul Offit, a vaccine expert at Children’s Hospital of Philadelphia, explained that vaccine doses are designed to fit the bodies of their patients, with children receiving much smaller doses than adults.
Offit said the president “isn’t always right about the science.”
