Drugs can have all sorts of adverse effects and unintended consequences. Some side effects are severe and impossible to ignore, but others are subtle. In the latter category is a side effect recently attributed to acetaminophen: People who take it may experience reduced empathy—the ability to share another person’s feelings.
Millions of Americans regularly take acetaminophen, which is found in pain relievers (such as Tylenol) as well as countless cold, allergy, and headache products. Its effect on empathy has been the focus of several studies.
In a study in Social Cognitive and Affective Neuroscience in 2016, researchers gave 80 undergraduate students either acetaminophen (1,000 milligrams in liquid form, equal to two extra-strength tablets) or a placebo. An hour later, participants read short scenarios about people experiencing physical pain or psychological distress, and then they completed questionnaires about their feelings. Compared to the placebo group, the acetaminophen group had reduced empathy—notably, they rated the protagonists’ pain lower and felt less personal distress and concern on their behalf.
This year, as reported in Frontiers in Psychology, the same researchers did a similar study on positive empathy—that is, the ability to share happy feelings. They gave 114 undergraduates either acetaminophen or a placebo. This time the printed scenarios were about people having uplifting experiences. Compared to the placebo group, the acetaminophen group reported significantly less pleasure when imagining the feelings of the protagonists, and they were less moved after reading the scenarios.
The researchers hypothesized that acetaminophen may affect parts of the brain in ways that reduce not only the perception of one’s own pain but also the ability to emotionally share—that is, empathize with—other people’s painful or pleasurable experiences.
Why does empathy matter? It provides “social glue” that can strengthen interpersonal relations and motivate compassionate behavior, the researchers noted. Given that so many people take the drug, they wrote, “our findings raise important questions about the societal impact of acetaminophen.”
It’s not known if other pain relievers would have this effect, or if the effect would subside—or worsen—with longer-term use.
Keep in mind, there are clearer reasons to limit the use of acetaminophen than its effect on empathy. Frequent use or large single doses can cause severe liver damage, especially in people who drink alcohol. In fact, acetaminophen overuse is the most common cause of acute liver failure in the U.S. If you find you need to take acetaminophen regularly, consult your doctor.