Over-the-counter headache pill paracetamol, also known as acetaminophen, reduces the pain of social rejection according to a new study just published in Psychological Science.

Based on past findings of an overlap between the brain circuits involved in physical pain and those involved in feeling rejected, the researchers wondered whether painkillers would also ease emotional distress stemming from exclusion.

Not all painkillers work the same though: some work by numbing the local nerves – like benzocaine-based sort throat lozenges that make your mouth go numb, while others affect the brain systems that process pain no matter where it originates from in the body.

Paracetamol is largely of the second type meaning if social rejection and physical pain really do share some of the same brain circuits, the drug should dull the hurt from both.

To test this out, the researchers recruited a group of healthy students and asked them to take a pill every day for three weeks: half got placebo while the other half were given paracetamol, although they didn’t know which they were taking.

Each evening the participants were asked to complete a standard questionnaire that asked about if they’d experienced hurt feelings or social exclusion during the day. While both groups started out reporting the same levels of hurt feelings, by the end of the three weeks, those taking paracetamol reported significantly less.

The second experiment of the study was similar but instead of filling in questionnaires the participants were asked to take part in a brain scanning experiment at the end of the three weeks.

Inside the scanner, they were asked to take part in a video game that involved tossing a virtual ball between players who they thought were human opponents. In reality, all the other moves were controlled by a computer programme that was preset to start excluding them from the game by not passing the ball to them.

The game was used in previous research and helped establish that brain activity in social rejection and physical pain overlapped.

The same overlap occurred in this new study, but the brain areas most linked to both physical and social pain – the anterior cingulate cortex and the insula – were less active in those who had been taking paracetamol for three weeks.

Those same participants also rated themselves as feeling less rejected on a brief post-game questionnaire than participants who had been taking placebo.

It’s an intriguing finding because it suggests that a common and cheap painkiller might be useful in reducing feelings of social rejection which can feature prominently in conditions like depression and borderline personality disorder.

If this was a brand new drug, you can bet the pharmaceutical industry would be jumping up and down with glee at these findings and would already be planning trials to see if it works as a useful treatment.

But because paracetamol is so old it can’t be patented and so there is virtually no profit to be made from it. Unfortunately, paracetemol can be toxic if taken too often, but it would be interesting to see if anyone does take up the baton to see if it might be a useful psychiatric treatment in appropriate doses.

Link to summary of study in PubMed.