Acetaminophen, known as Tylenol in the US, does not increase the risk of autism when taken during pregnancy, according to a comprehensive new study from Denmark published in Jama Pediatrics. The research tracked more than 1.5 million children born between 1997 and 2022, including over 31,000 exposed to the painkiller in utero.
Autism was diagnosed in 1.8% of children exposed to acetaminophen, compared to 3% of those who were not exposed. The findings contradict claims made by former US President Donald Trump, who has repeatedly asserted that the medication is linked to “a very increased risk of autism”.
The Danish study, which leveraged the country’s national health registry, adds to a growing body of evidence. A similar Swedish study in 2024 found a marginal link that disappeared after accounting for siblings, suggesting a strong genetic component to autism. In the US, a 2025 review identified a potential relationship but could not rule out confounding factors—for example, that pregnant women with autism may take acetaminophen more often due to higher pain levels.
Despite these findings, the US Food and Drug Administration (FDA) announced in September 2025 it would initiate a label change for acetaminophen warning of a potential link to autism. Following this, orders of the drug for pregnant women in emergency rooms dropped by 16%, according to a study in The Lancet. Jeremy Faust, a co-author of that study and emergency physician at Mass General Brigham, noted that health officials’ “words are affecting behaviour”.
Acetaminophen is considered one of the safest options for pain and fever during pregnancy, as alternatives like ibuprofen carry bleeding risks. Dr Faust stressed that pain itself is a problem, and was relieved to see that opioid prescriptions did not increase during the study period. The September announcement also promoted leucovorin for autism treatment, a claim that was later quietly retracted.
