Researchers from Ohio State University have discovered that the commonly used pain reliever, acetaminophen, has a previously unknown side effect: it kills positive emotions. In the study, participants who took acetaminophen reported feeling fewer strong emotions when they were shown very pleasant or very disturbing photos, compared to those who took placebos. You might be thinking correlation doesn’t mean causation, but when you use the Bradford Hill criteria, and examine all of the other studies done regarding the psychological effects of over the counter pain killers, the picture becomes clearer. MORE