Acetaminophen helps dull the pain of some 52 million Americans each week, but new research suggests it could also blunt their sensitivity to other people’s distress. Researchers conducted a series of experiments involving 200 college students to assess the effects of acetaminophen – an active ingredient in Tylenol and more than 600 other medications – on their ability to empathize. Participants read eight short stories with wrenching scenarios – one told of a person who suffered a knife wound that cut to the bone; in another, someone grappled with the death of his father. As it turned out, CNN.com reports, the students who took 1,000 mg of acetaminophen (equivalent to two extra-strength Tylenol tablets) displayed less empathy for people who were enduring an emotionally or physically painful experience. “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 study author Baldwin Way. “We don’t know why acetaminophen is having these effects,” but it is cause for concern.