Acetaminophen has been used for decades as an effective over-the-counter pain reliever with many people all over the world taking it on a regular basis. New research on this common pain reliever has found that the drug ingredient may do more than just relieve pain, it may also dampen emotions as well.

The main ingredient in the over the counter pain reliever Tylenol, has been in use for more than 70 years in the United States. It is the most common drug ingredient in the United States and is currently found in more than 600 medicines. Each week approximately 23 percent of American adults use medicine containing acetaminophen.

In the study, participants who took acetaminophen reported less strong emotions when shown both very pleasant and very disturbing photos compared to those who took a placebo.

Previous research has already shown that the over the counter drug works on both physical and psychological pain, but this study takes it one step farther demonstrating that it also reduces how much positive emotions they experience.

"This means that using Tylenol or similar products might have broader consequences than previously thought," says Geoffrey Durso, lead author of the study and a doctoral student in social psychology at Ohio State University.

"Rather than just being a pain reliever, acetaminophen can be seen as an all-purpose emotion reliever."

Dr. Baldwin Way, an assistant professor of psychology at Ohio State said people in the study who took the pain reliever didn't appear to know they were reacting differently. "Most people probably aren't aware of how their emotions may be impacted when they take acetaminophen," he said.

When viewing the images, positive photos were not seen as positively under the influence of acetaminophen and negative photos were not seen as negatively. The same was true of their emotional reactions.

"People who took acetaminophen didn't feel the same highs or lows as did the people who took placebos," Way said.

This study offers support to a relatively new theory that states that common factors may influence how sensitive we are to both the good and the bad things in life. That means that a person devastating by a death or a divorce would thrive more on positive news such as a promotion at work as well. In this study, acetaminophen may have actually tapped into the sensitivity that make some people react differently to both positive and negative events in their lives.