Next time you take a painkiller, your sensitivity to pain may not be the only thing reduced. You may also be reducing your sensitivity to pleasure

Researchers in the U.S have found that the common pain reliever acetaminophen has a previously unknown side effect of reducing positive emotion.

Previous studies show that acetaminophen reduces both physical and psychological pain, but this new study, published online in the journal Psychological Science, is the first to examine the effect on positive emotions.