Researchers Examine Why Tylenol Affects Empathy

Nearly one quarter of all Americans reach for a bottle of Tylenol every week to take the edge off a headache, fever or toothache. Experiments suggest it might also have another effect on you.

DAVID GREENE, HOST:

Nearly one-quarter of all Americans reach for a bottle of acetaminophen every single week. Many of you might know this drug as Tylenol. It's a pain killer that can take the edge off a headache or treat you when you have a fever. It also might have another effect. And let's talk about this with NPR social science correspondent Shankar Vedantam. And, Shankar, straight out, is this going to make me not want to take Tylenol, what you're about to tell me?

SHANKAR VEDANTAM, BYLINE: It might make you not want to take Tylenol.

GREENE: All right, what's going on?

VEDANTAM: It might make you not want to take Tylenol when you're talking with me, David.

GREENE: Oh, even more interesting.

VEDANTAM: (Laughter) I was speaking with Dominik Mischkowski. He's currently a researcher at the National Institutes of Health. He recently conducted a couple of double blind experiments. These are experiments where the volunteers are given either sugar pills or Tylenol, but neither the volunteers nor the researchers know which volunteers are getting which pill. Mischkowski and his advisers at Ohio State University, Jennifer Crocker and Baldwin Way, they played loud noises for the volunteers. Not surprisingly, volunteers given Tylenol experienced less physical discomfort than volunteers given the placebo.

GREENE: Because they had been sort of treated preliminarily. And it would have - if noise was going to cause pain, it didn't cause as much to the people with Tylenol, OK.

VEDANTAM: Exactly, Tylenol's a painkiller.

GREENE: Got you.

VEDANTAM: But here's the interesting thing - the researchers also measured the empathy that volunteers felt for the pain of other people. Here's Mischkowski.

DOMINIK MISCHKOWSKI: We gave participants eight scenarios which described people in either physical pain or social pain. Physical pain meaning, for example, injuring the shin. Social pain would be experiencing rejection in a peer group. And we found that acetaminophen basically reduced empathy for the pain of those people.

GREENE: Taking this painkiller made you not care as much about what other people were going through.

VEDANTAM: That's right. Now, the effect is not huge, but Mischkowski told me there was about a 10 percent difference in both the physical discomfort volunteers experienced when they were subjected to the noise blast and in their empathic perception of the pain of someone else.

GREENE: What exactly is happening here? Am I feeling great about myself because I'm in less pain, and that makes me not care if you're in pain? Or what is - what is happening?

VEDANTAM: Well, here's the theory the researchers are playing with. There's been other work that suggests there are overlaps in how the brain processes physical and social pain. In 2010, for example, Nathan DeWall at the University of Kentucky and his colleagues found that volunteers given Tylenol experience less social pain as well as less physical pain. Here's Mischkowski.

MISCHKOWSKI: When people experience physical pain - so, for example, having a hot probe on their arm - and then see somebody else experiencing the same pain or similar pain, then the same areas in the brain light up.

VEDANTAM: So, David, when you think about empathy, empathy is really about feeling the pain of someone else.

GREENE: I can feel your pain, yeah.

VEDANTAM: You feel bad that someone else is suffering, exactly. If Tylenol has a capacity to reduce physical pain, it makes sense it could have an effect on our ability to experience emotional pain as well.

GREENE: So is it just Tylenol, or we think this might be other painkillers as well doing this?

VEDANTAM: So this study was focused just on Tylenol. I think it's reasonable to speculate, David, that other painkillers might have the same effect, if you buy the idea that physical pain and emotional pain are perceived the same way in the brain and painkillers can affect both.

GREENE: Does this mean if you're going to the drug store to buy some Tylenol, like, make sure your friends or loved ones aren't around because you're not going to want to help them, or what?

VEDANTAM: (Laughter) Well, the first thing to say is that the effects of Tylenol on empathy are somewhat modest. We're not talking of a 0 to 100 percent difference here.

GREENE: OK.

VEDANTAM: We're talking about maybe a 10 percent difference. But, you know, a quarter of the American population aged 18 to 65 uses acetaminophen or a drug containing acetaminophen every week. Not all people respond to a drug the same way. It probably has stronger effects on some people. Since the overall number of users is very large, it might be a side effect worth thinking about.

GREENE: All right. That is NPR's social science correspondent, Shankar Vedantam. He's also the host of a podcast that explores the unseen patterns in human behavior. It's called Hidden Brain. He's also a tremendously empathetic colleague. Shankar, thank you.

VEDANTAM: (Laughter) Thanks, David.

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