Paracetamol may be an effective pain reliever but it also reduces feelings of pleasure, a new study suggests. The new side effect means that over-the-counter painkillers are leaving users not only pain-free, but also emotionally numb.In a study carried out by US researchers, volunteers who took paracetamol reported weaker feelings when they saw both pleasant and harrowing photographs.Previous research had shown that the pain-killer works not only on physical pain, but also on psychological pain. However the new study takes those results one step further by showing that it also reduces how much users actually feel positive emotions.Researchers asked 82 volunteers to take 1000mg of paracetamol or a placebo. After waiting 60 minutes for the drug to take effect, they were asked to rate 40 photographs on whether the image made them feel positive or negative.The photographs ranged from the extremely unpleasant, such as crying, malnourished children, to neutral images, like a cow in a field and very pleasant, such as children playing with kittens.Results showed that participants who took acetaminophen rated all the photographs less extremely than did those who took the placebo.In other words, positive photos were not seen as positively under the influence of acetaminophen and negative photos were not seen as negatively. The same was true of their emotional reactions. ..