Pain and fever reducer acetaminophen, most-used drug in U.S., is found to reduce positive emotions and reduce psychological pain

Ohio State University researchers discovered a new side effect of acetaminophen, a leading over-the-counter pain reliever: it also blunts positive emotions. Other research revealed that it helps reduce psychological pain. The drug has been used in the U.S. for more than 70 years and is best known by the brand name Tylenol.

In the Ohio study, participants took Tylenol or a placebo, then looked at very pleasant or very disturbing photos. Those in the experimental group reported weaker emotions than those in the control group. On average, those who took the placebo rated their level of emotion when viewing the photos at 6.76 on a scale of 10, while people who took the pain reliever averaged 5.85.

“Rather than just being a pain reliever, acetaminophen can be seen as an all-purpose emotion reliever,” said Geoffrey Durso, the lead author of the study and a doctoral student in social psychology.

Balwin Way, an assistant psychology professor who conducted the study with Durso, said those who took Tylenol didn’t seem to be aware they were reacting differently. “Most people probably aren’t aware of how their emotions may be impacted when they take acetaminophen,” he said.

Acetaminophen, found in more than 600 medicines, is the most common drug in the U.S., according to the Consumer Healthcare Products Association. Every week approximately 52 million American adults, 23 percent of the population, use a medicine with acetaminophen in it. Durso said researchers don’t know if other pain relievers like ibuprofen and aspirin have similar effects, but they plan to study that question.