Is autism linked to Tylenol, also known as paracetamol? What the research says

US President Donald Trump on Sept 22 advised pregnant women to avoid taking Tylenol, saying

the painkiller might be linked to autism.

Mr Trump did not cite scientific evidence to support his recommendation, and there is no clear connection between the use of Tylenol during pregnancy and adverse neurobehavioural or developmental outcomes such as autism. 

On the same day as Mr Trump’s remarks, the US Food and Drug Administration issued a notice to physicians about what the Trump administration said were the risks of Tylenol during pregnancy, while noting that a “causal relationship has not been established” between autism and acetaminophen, Tylenol’s active ingredient. The drug is known outside the US as paracetamol.

Mr Trump’s announcement was the latest example of how he and Health and Human Services (HHS) Secretary Robert F. Kennedy Jr have sought to upend longstanding health guidance and practices, including by citing unproven and debunked theories to criticise vaccine policies for children.

Here is what the science says about whether there is a link between Tylenol and autism.

What does research say about autism and acetaminophen? 

Findings from studies have been mixed.

What is more, research investigating the link between autism and acetaminophen has relied not on controlled experiments but on observational studies, in which researchers collect data on a group of people and try to connect something about them with a certain outcome. As so many other factors can affect the outcome, such studies have a limited ability to determine causality. Their results often cannot be replicated.

One 2008 study found acetaminophen use in babies age 12 to 18 months with fevers was associated with a diagnosis of autism spectrum disorder. The study did not reach a definitive conclusion, and the researchers called for more analysis.

A 2019 study from Johns Hopkins Bloomberg School of Public Health linked exposure to the drug in the womb to autism.

In 2024, a broad study analysed the records of 2.5 million siblings born in Sweden over 25 years and found no increased risk of autism when their mothers took acetaminophen while pregnant. 

Earlier in 2025, a review of 46 previous studies found that prenatal exposure to acetaminophen might increase the risk of neurodevelopmental disorders, but did not find that it directly caused them. 

One of that study’s authors, Dr Andrea Baccarelli, dean of Harvard T.H. Chan School of Public Health, was an expert witness for plaintiffs claiming prenatal exposure to Tylenol caused autism.

Dr Baccarelli had his testimony excluded by a judge, who wrote that he had not used “sufficient rigour” in measuring the association between in utero exposure to acetaminophen and neurodevelopmental disorders.

The judge concluded that plaintiffs in more than 400 acetaminophen suits had relied on flawed science.

Kenvue Inc, the manufacturer of Tylenol, points to “independent, sound science” that shows acetaminophen does not cause autism.

Have rates of autism diagnosis increased? 

Yes. A 2024 study found the autism diagnosis rate increased by 175 per cent over a decade.

This is partly due to a broader definition in the edition of the Diagnostic and Statistical Manual of Mental Disorders published in 1994 that included Asperger’s syndrome. In addition, it reflects increased diagnostic testing, especially of young adults instead of only young children. 

A study from the US Centres for Disease Control and Prevention found that one in 31 eight-year-olds were diagnosed with autism in 2022. Boys are also three times more likely to be diagnosed with the condition than girls. 

What are the current recommendations for pregnant women? 

Women are typically told to take acetaminophen for pain or fever, using the lowest effective dose for the shortest period of time.

For many, it is the only way to treat those issues, as pregnant women should avoid taking ibuprofen and other non-steroidal anti-inflammatory drugs, which can cause kidney problems in the unborn child and low amniotic fluid levels. 

The American College of Obstetricians and Gynaecologists has said that acetaminophen is one of the few safe pain relievers for pregnant women, and patients should not be “frightened away” from taking the drug. 

On Sept 22, the UK’s Medicines and Healthcare Products Regulatory Agency issued a statement reaffirming that paracetamol is safe to take during pregnancy, and that there is no evidence it causes autism in children. 

What are the risks of running a fever during pregnancy? 

While President Trump suggested during his Sept 22 remarks that pregnant women should use Tylenol to control a fever only if they cannot “tough it out”, having a fever during pregnancy increases the odds of serious and sometimes fatal birth defects, including spina bifida. It also raises the chances of miscarriage.

Blaming acetaminophen for autism could increase risks to women’s health, said Dr David Mandell, an epidemiologist at the University of Pennsylvania, who studies autism.

“I’m very concerned that pregnant women who have fevers will let them go untreated,” he said. 

What has Robert Kennedy said about autism?

Previously, Mr Kennedy had long promoted the idea that vaccines cause autism, a debunked theory that stems from a fraudulent scientific paper that was retracted in 2010.

The UK’s General Medical Council stripped the paper’s author, Dr Andrew Wakefield, of his medical licence for “dishonest” and “irresponsible” work. By then, some parents had latched on to the idea that vaccines were to blame for a rise in autism diagnoses.

In April, two months after he was sworn in as HHS Secretary, Mr Kennedy’s agency reported that one in 31 children were being diagnosed with autism as of 2022. Mr Kennedy said that Mr Trump had told him to find the root causes of many childhood diseases, including autism. 

There have been some recent calls from Kennedy supporters about the supposed dangers of acetaminophen.

Right-wing activist Laura Loomer posted on social media platform X on Sept 2 and speculated about the link. Children’s Health Defence, the anti-vaccine advocacy organisation that Mr Kennedy founded, speculated about the link as recently as Sept 15. BLOOMBERG