By Pat Anson, Editor
A popular over-the-counter pain reliever may do more than just relieve minor aches and pains. Ohio State researchers say acetaminophen -- the active ingredient in Excedrin and hundreds of other pain medications -- can also make us feel less empathy for the physical and emotional pain of others.
"We don't know why acetaminophen is having these effects, but it is concerning," says Baldwin Way, an assistant professor of psychology at Ohio State’s Wexner Medical Center's Institute for Behavioral Medicine Research.
“Empathy is important. If you are having an argument with your spouse and you just took acetaminophen, this research suggests you might be less understanding of what you did to hurt your spouse's feelings."
Acetaminophen -- also known as paracetamol – is the world’s most widely used over-the-counter pain reliever. The study findings were published in the journal Social Cognitive and Affective Neuroscience.
Way and his colleagues divided 80 college students into two groups, giving half of them a liquid containing 1,000 mg of acetaminophen, while the other half drank a placebo solution that contained no drug. The students didn't know which group they were in.
After waiting an hour for the drug to take effect, the students read eight short scenarios in which someone suffered some sort of physical or emotional pain. For example, one scenario was about a person who suffered a knife wound and another was about a person whose father died. Participants were then asked to rate the pain of each person on a scale ranging from 1 (no pain at all) to 5 (worst possible pain).
Students who took acetaminophen rated the pain of the people in the scenarios to be less severe than those who took the placebo.
"These findings suggest other people's pain doesn't seem as big of a deal to you when you've taken acetaminophen," said Dominik Mischkowski, co-author of the study and a former PhD. student at Ohio State, who is now at the National Institutes of Health.
In a second experiment, students met and socialized with each other briefly. Each participant then watched, alone, an online game that purportedly involved three of the people they just met. In the game, two of the students excluded the third person from the activity.
Participants were then asked to rate how much pain and hurt feelings the students in the game felt, including the one who was excluded.
Results showed that people who took acetaminophen rated the pain and hurt feelings of the excluded student as less severe than the participants who took the placebo.
"Participants had the chance to empathize with the suffering of someone who they thought was going through a socially painful experience," Way said. "Still, those who took acetaminophen showed a reduction in empathy. They weren't as concerned about the rejected person's hurt feelings.
“Because empathy regulates pro-social and anti-social behavior, these drug-induced reductions in empathy raise concerns about the broader social side effects of acetaminophen, which is taken by almost a quarter of U.S. adults each week.”
An earlier Ohio State study found that acetaminophen also dulls emotions.
The pain reliever has long been associated with liver injury and allergic reactions such as skin rash. In the U.S. over 50,000 emergency room visits each year are caused by acetaminophen, including 25,000 hospitalizations and 450 deaths.