A large study by researchers from Denmark has again confirmed that taking acetaminophen – known in the US as Tylenol and paracetamol in South Africa – during pregnancy has no effect on later autism diagnoses, reports The Guardian.
Through their country’s robust healthcare system, the Danish researchers tracked more than 1.5m children born between 1997 and 2022 in the national health registry, including 31 098 youngsters who were exposed to Tylenol in utero.
Autism was diagnosed in 1.8% of children who were exposed to Tylenol and 3% of those who weren’t, according to the study, which was published in JAMA Paediatrics.
A similar 2024 study in Sweden found a marginal link that disappeared after taking siblings into account, suggesting that autism is strongly genetic, which has already been demonstrated in other studies.
A US review of existing studies in 2025 found a potential relationship, but it wasn’t clear whether confounders were at play: for instance, if pregnant autistic women take Tylenol more often than neurotypical pregnant women because of higher pain levels.
American health officials announced in September last year that the Food and Drug Administration (FDA) would initiate a label change for acetaminophen, warning of a potential link to autism. President Donald Trump also cautioned several times against taking the pain reliever during pregnancy.
Experts say Tylenol is safe to take during pregnancy and can play a key role in relieving pain and bringing down fevers.
Yet after the September announcement, Tylenol orders for pregnant women in emergency rooms dropped by 16% in the initial study period, according to aLancet study published last month.
Health officials’ “words are affecting behaviour”, said Jeremy Faust, a co-author of that Lancet study, an emergency physician at Mass General Brigham and a health services researcher at Harvard Medical School.
The rate of emergency orders of Tylenol dropped as low as 20% three weeks after the announcement before it began drifting to a 10% reduction, as the news cycle changed and respiratory virus season ramped up, he said. There was no change for Tylenol order rates among women of the same age who were not pregnant, and no declines in orders for other medications, such as IV fluids or opioids.
Tylenol is one of the few medications people may take during pregnancy. “It’s the safest option for pain control and fever reduction,” Faust said. Non-steroidal anti-inflammatory drugs such as ibuprofen usually are not recommended because of bleeding risks and potential placenta issues.
“Pain is, in itself, a problem,” Faust said, expressing relief that doctors’ orders for opioids, which can also manage pain, did not increase in the study period.
At the same September press conference, officials announced that leucovorin, a B vitamin, could be used to treat autism. That claim was quietly walked back earlier this year.
The Guardian article – Taking Tylenol during pregnancy has no link to autism, new study finds
See more from MedicalBrief archives:
No link between Tylenol and autism in children – UK review
SA expert groups dismiss Trump's paracetamol link to autism