Paracetamol's worrying side effect

A common chemical found in paracetamol can dull feelings of both pleasure and pain, a new study has found.

Researchers from Ohio State University studied the effects of acetaminophen – the most common active ingredient in the over-the-counter pain medication – and found it may dull emotions, reducing both positive and negative feelings.

More: Health studies with obvious results

The study, published in the journal Psychological Science revealed that the effects can go beyond relieving pain. “Rather than being just a pain reliever, acetaminophen can be seen as an all-purpose emotion reliever,” said Geoffrey Durso, lead study author and a social psychologist at the university.

After giving 82 students either 100mg of acetaminophen or a placebo pill, he asked them to look at a series of 40 photographs. A whole range of pictures were included, from images of children playing with cats to photos of distraught, malnourished children, each designed to elicit an emotional response. Each student was asked to rate each photo according to a scale from -5 (extremely negative) to +5 (extremely positive).

More: Severe stress can reduce longevity

Those who took paracetamol had less intense reactions to the images, regardless of how happy or harrowing the photos were. “People who took acetaminophen didn’t feel the same highs or lows as did the people who took placebos,” said study co-author Baldwin Way.

It’s not the first time researchers have discovered other side-effects to paracetamol. One previous study from the University of California found that acetaminophen could reduce emotional pain too.

While the difference in emotional response between students was not large (students who took the placebo had an average response of 6.76, compared to 5.85 for those on paracetamol), researchers are planning follow-up studies on the effects of other painkillers such as ibuprofen and aspirin.