One of the world's most-common analgesics could be reducing users' capacity to feel empathy.  US Scientists published a study claiming that acetaminophen - the main ingredient in Panadol and Tylenol - makes people more likely to think that other people's pain isn’t a big deal.

Researchers from the National Institutes of Health and Ohio State University studied the effects of the drugs on between 80 and about 120 college students across three different experiments.  In each, the students were asked to give their opinion of the pain that others felt or would feel in various situations: short stories about the loss of a parent, or physical pain caused by a knife; exclusion from social situations; and exposure to loud noise. 

In most cases, the students who were given a placebo showed empathy to suffering - the students who took 1,000mg of acetaminophen assigned lower ratings for perceived pain of others.

The size of the sample in the experiments was small, and the researchers didn't determine why this effect happens.  The results suggest that there is an overlap in our ability to experience pain and our ability to empathize with others.  Earlier studies have shown that acetaminophen makes people less likely to feel joy and that it can help help treat anxiety and existential dread.