Following on from a series of similar studies, researchers are once again investigating whether acetaminophen can influence our psychology. This time, the focus is on positive empathy.

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Could acetaminophen reduce our ability to demonstrate empathy?

Acetaminophen is one of the most commonly used drugs globally.

It offers quick relief from mild pain and is readily available over the counter.

Although the medical community considers acetaminophen to be a relatively safe and useful drug, a recent study asks whether it might have an unexpected effect on the population at large.

Researchers from Ohio University in Athens are examining its effect on our ability to empathize with others.

Lead author Dominik Mischkowski has been interested in this unusual topic for some time.

Although the idea that a popular analgesic might have a psychological effect seems surprising, Mischkowski is not the only person to have investigated it.

For instance, a 2010 paper concluded that acetaminophen “reduced neural responses to social rejection.” In other words, it appeared to reduce psychological pain.

A study from 2015 concluded that acetaminophen blunted “evaluative and emotional processing,” while a more recent study involving people with borderline personality disorder found that acetaminophen increased their level of trust.

Mischkowski published the findings of a study in 2016, and Medical News Today covered it at the time. In the paper, the researchers explained how acetaminophen seemed to reduce participants’ ability to empathize with those undergoing physical and emotional suffering.

According to Mischkowski, this common pain reliever blunts responsiveness to one’s own pain and also to the pain of others.

I’m still surprised about the striking psychological effects of such a common painkiller.”

Lead author Dominik Mischkowski

In his latest study, Mischkowski wanted to expand on his previous work. Specifically, he set out with his colleagues to explore whether acetaminophen might also reduce someone’s ability to experience positive empathy.

To investigate, the researchers recruited 114 participants. They gave half of the group 1,000 milligrams of acetaminophen, while the other half received an inert placebo. The study was double-blind, meaning that neither the researchers nor the participants knew whether they were receiving the active drug or the placebo.

One hour later, the team asked the participants to read short passages about people having positive, uplifting experiences. The researchers measured how positive the participants perceived the events to be and how positive they thought they were for the individuals in the narrative.

Once the scientists had completed their analysis, the results confirmed their expectations:

“[A]cetaminophen reduced positive empathy. When reading scenarios about various protagonists having pleasurable experiences, participants under the influence of acetaminophen experienced less empathic affect compared to participants who had consumed a psychologically inert placebo.”

Importantly, the researchers also found that acetaminophen did not dull the participants’ ability to understand that the situations that they were reading about were positive — they realized the emotional impact, but they did not feel much empathy for the individuals in the narratives.

Although these findings contribute to a growing body of similar research, most of the studies are small-scale and generally involve fewer than 100 participants. So, although interest is growing, it is not yet possible to gauge the size of acetaminophen’s effect on empathy, if it does exist.

It may be that this effect is small or that the drug only affects some people, but due to the widespread use of this pain reliever, even a small effect could be significant.

Given that an estimated quarter of all U.S. American adults consume a drug containing acetaminophen every week, this research really matters.”

Dominik Mischkowski

As the authors explain, there is a need for other studies to replicate and build on these results. There are a number of ways in which researchers could strengthen the study. For instance, inducing empathy in real-life situations would be preferable to merely reading emotive texts.

It is also worth noting how difficult it is to quantify empathy or any other human emotion for that matter. In this particular study, the team asked the participants to rate the extent to which they felt, for instance, pleasure, uplifted, or pleased, using a five-point scale from “not at all” to “extremely.”

Using an individual’s self-rating is problematic for several reasons. As an example, it could be that the participant was not experiencing decreased empathy but simply a reduced desire to share their feelings.

That said, even if acetaminophen does not alter empathy, it appears to lead to a measurable change in the way that participants respond to a questionnaire, which is still interesting.

The idea that such a common medication could cause a psychological effect, even if it is subtle, is intriguing. However, few studies have addressed these questions, and scientists will need to do much more detailed work before we can conclude that acetaminophen reduces empathy in a meaningful way.