Comprehensive Review Finds No Clear Link Between Tylenol, Autism

An in-depth review of existing research on autism and Tylenol that was conducted in direct response to recent claims by President Donald Trump finds that there is no definitive link between the two.

Researchers examined nine systematic reviews including 40 studies looking at the use of acetaminophen, also known as paracetamol, during pregnancy and the risk of autism, ADHD and other neurodevelopmental issues.

All of the reviews found a “possible to strong association” between use of the pain reliever sold under the brand name Tylenol and autism, ADHD or both. However, the analysis published in The BMJ this week found several weaknesses in the studies.

Seven of the reviews advised caution in their findings due to bias and other factors. When the researchers accounted for bias, overall confidence in two of the reviews was “low,” while the other seven were deemed “critically low.” There was also significant overlap across the reviews.

The analysis found that just one review included studies adjusting for genetic and environmental factors shared by siblings as well as other background and lifestyle considerations. When these issues were considered, any association between Tylenol and autism disappeared, suggesting that any link was related to genetic or environmental factors within families.

“Through this work, we have shown that based on current evidence, there is no clear link between women taking paracetamol during pregnancy and a diagnosis of autism or ADHD in their children,” said Shakila Thangaratinam, a professor at the University of Liverpool who led the study. “The findings should help healthcare professionals give evidence-based advice to women, and reassure mothers about the use of paracetamol during pregnancy if indicated.”

Tylenol is used to treat pain and fever during pregnancy. However, concerns that the drug could lead to an increased risk of autism in children exposed in utero escalated as a result of a Trump administration press conference in September during which Trump told expectant mothers “Don’t take Tylenol.”

The American College of Obstetricians and Gynecologists has consistently maintained that acetaminophen is one of the only safe options to treat pain and fever during pregnancy, which the groups says can be harmful if left untreated.