Acetaminophen Linked to Autism and ADHD

By Pat Anson, Editor

An over-the-counter pain reliever widely used by pregnant women has been linked to autism and attention deficit problems in their children, according to researchers.

In a new study involving over 2,600 Spanish women and their children, published online in the International Journal of Epidemiology, researchers said maternal use of acetaminophen – also known as paracetamol -- appears to increase the risk of autism spectrum disorder (ASD) in boys. There was also a “weak” association between acetaminophen and attention deficit disorder (ADHD) in both male and female children.

“To our knowledge, this is the first prospective study to report an independent association between the use of acetaminophen during pregnancy and autism spectrum symptomatology in exposed children. It is also the first paper to report differential gender effects of prenatal acetaminophen exposure on neurodevelopment,” the researchers said.

About 40 percent of the women in the study used acetaminophen while pregnant. Their children were evaluated at 1 and 5 years of age.

The researchers speculated that boys may metabolize acetaminophen differently than girls, accounting for the greater risk of autism.

“Animal studies have suggested that male mice undergo greater toxicity than female mice after being administered a similar dose of acetaminophen. Furthermore, the male brain may be more vulnerable to early life stressors  and this could explain why neuropsychiatric disorders of childhood, such as ASC and ADHD, are more prevalent in male children,” they said.

Acetaminophen (paracetamol) is the world’s most widely used over-the-counter pain reliever. It is the active ingredient in Tylenol, Excedrin, and hundreds of other pain medications.

In a review of the study, the UK’s National Health Service (NHS) said researchers failed to prove a clear link between maternal use of acetaminophen and autism or ADHD.

“This research cannot prove paracetamol use is directly responsible for these findings. Not all links were statistically significant – for example, paracetamol was not linked with ADHD when looking at full diagnostic criteria, or with ASD when looking at the full sample of children,” the NHS said. “Importantly, no link was found with developmental or intellectual outcomes in the child.

“The current viewpoint is that occasionally using paracetamol as needed, and at recommended doses, is safe during pregnancy. This study has not provided sufficient evidence to the contrary to change this advice.”

Over 50 million people in the U.S. use acetaminophen each week to treat pain and fever. The pain reliever has long been associated with liver injury and allergic reactions such as skin rash.

Another recent study of pregnant women found that Lyrica (pregabalin) – a medication also prescribed for pain – appears to  increase the risk of major births defects, including heart defects and structural problems with the central nervous system.