Sarah Knapton
PARACETAMOL is an effective pain reliever but also reduces feelings of pleasure, a study suggests.
The previously unknown side-effect means that over-the-counter painkillers are leaving users not only pain-free, but also emotionally numb.
Most people probably aren't aware of how their emotions may be impacted when they take paracetamol.
In a study carried out by US researchers, volunteers who took paracetamol reported weaker feelings when they were shown photographs that were either pleasant or harrowing, compared with volunteers who had not taken the drug.
"This means that using paracetamol might have broader consequences than previously thought," said Geoffrey Durso, the lead author and a doctoral student in social psychology at Ohio State University.
"Rather than just being a pain reliever, paracetamol can be seen as an all-purpose emotion reliever." Previous research had shown that the painkiller works not only on physical pain, but also on psychological pain.
However, the new study took those results one step further by showing that it also reduces how users experience positive emotions.
Dr Baldwin Way, assistant professor of psychology at Ohio State, added: "Most people probably aren't aware of how their emotions may be impacted when they take paracetamol.
"People who took acetaminophen (paracetamol) didn't feel the same highs or lows as did the people who took placebos."
Researchers asked 82 volunteers to take 1000mg of paracetamol - the equivalent of two normal tablets - 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, such as a cow in a field, to very pleasant, such as children playing with kittens.
Results showed that participants who took paracetamol reported a less extreme reaction to all the photographs than did those who took the placebo.
The same was true of their emotional reactions.
Those who took the placebo rated their level of emotion relatively high, with an average score of 6.76 out of 10, when they saw the most emotionally jarring photos of the malnourished child, or the pleasant image of children with kittens.
People taking paracetamol reporting less pronounced reactions at both ends of the emotional spectrum, with an average level of emotion of 5.85 when they saw the extreme photos.
Neutral photos were rated similarly by all participants, regardless of whether they took the drug or not.
The team now plans to study whether other pain relievers such as ibuprofen and aspirin have the same impact.
Previous studies have suggested that ibuprofen could be used to treat depression but researchers believed that was due to its anti-inflammatory properties.
The research was published in the online journal Psychological Science.
The Telegraph, London
