This Tylenol Ingredient May Affect Your Empathy

A small recent study suggests that taking acetaminophen may not only dull your physical pain, but your ability to feel others’ pain as well.

Acetaminophen, which is the painkiller in Tylenol, is the most common drug ingredient in the U.S, according to the Consumer Healthcare Products Association. The trade group has reported that each week, about 23% of American adults use a medicine containing acetaminophen. In the new study, researchers at Ohio State University set out to investigate the med’s impact on empathy.

In one experiment, they had 40 college students drink a liquid containing 1,000mg of acetaminophen, while another group of 40 students was given a placebo liquid. The students then read scenarios in which someone suffered some sort of ache—physical or emotional—and were asked to rate the pain those people experienced. The study participants who drank the acetaminophen rated their suffering as significantly lower compared to the students who drank the placebo.

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In a second experiment, again one group of students was given acetaminophen, and the other, a placebo. Then they were all exposed to short blasts of white noise, and asked to rate the noise on a scale from 1 (not unpleasant) to 10 (extremely unpleasant). Finally, they were asked to imagine how unpleasant those blases of noise would seem to others.

Compared to the placebo group, the students who took acetaminophen rated the noise as being less unpleasant, and predicted that the noises would be less unpleasant for others as well.

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“We don’t know why acetaminophen is having these effects, but it is concerning,” said researcher Baldwin Way, PhD, in a press release. “Empathy is important. If you are having an argument with your spouse and you just took acetaminophen, this research suggests you might be less understanding of what you did to hurt your spouse’s feelings.”

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In an earlier study, Way and his co-author Dominik Mischkowski, PhD, found that acetaminophen may have another unexpected side effect: dulling positive emotions, like joy. It’s seems there may be a lot we don’t know about over-the-counter painkillers. Next Mischkowski and Way plan to study another common painkiller, ibuprofen, to see if it’s linked to similar effects.

This article originally appeared on Health.com