If the results of a new study hold up to further research, Tylenol may have to start coming up with a new warning label: "may cause a lack of empathy." Researchers studying acetaminophen—the active painkiller in Tylenol and about 600 other medicines—found people taking it showed less empathy toward the physical and emotional pain of others, Live Science reports. This could be a big deal as nearly a quarter of American adults take some form of acetaminophen every week, notes an Ohio State press release. "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," says the study's senior author, Baldwin Way.
The study—published in Social Cognitive and Affective Neuroscience—consisted of multiple experiments involving stories of suffering, actual painful blasts of noise, and more, CNN reports. The results appear to confirm earlier studies of brain activity that showed empathy was somehow neurologically related to how a person processes their own pain. The results also "raise concerns about the broader social side effects of acetaminophen," says the study. “We don’t know why acetaminophen is having these effects, but it is concerning,” says Way. The researchers plan to test ibuprofen next. (Another recent study shows acetaminophen could reduce your ability to notice errors.)