Common Pain Reliever May Stifle Joy

A common pain reliever may stifle feelings of joy and happiness, according to a new study.

Acetaminophen, the main ingredient in the over-the-counter pain reliever Tylenol, has been in use for more than 70 years in the United States. However, this is the first time that scientists have found a previously unknown side effect: it reduces positive emotions.

That is, according to recent findings published in the journal Psychological Science, which detail how participants who took acetaminophen reported less strong emotions when they saw both very pleasant and very disturbing photos, when compared to those who took placebos.

"This means that using Tylenol or similar products might have broader consequences than previously thought," lead author Geoffrey Durso, from The Ohio State University, said in a statement. "Rather than just being a pain reliever, acetaminophen can be seen as an all-purpose emotion reliever."

Previous research had shown that acetaminophen works not only on physical pain, but also on psychological pain. To better understand its effects, Durso and his colleagues studied about 82 college students. About half of them took an acute dose of 1000 milligrams of acetaminophen and the rest took an identical-looking placebo. After waiting an hour for the drug to work, participants looked at 40 photographs selected from a database - ranging from the extremely unpleasant (crying, malnourished children) to the neutral (a cow in a field) to the very pleasant (young children playing with cats).

After viewing each photo, participants were asked to rate how positive or negative the photo was on a scale of -5 (extremely negative) to +5 (extremely positive). They then viewed the same photos again and were asked to rate how much the photo made them feel an emotional reaction, from 0 (little or no emotion) to 10 (extreme amount of emotion). (Scroll to read on...)

According to the results, those who took acetaminophen rated all the photographs less extremely than did those who took the placebo. This means that positive photos were not seen as positively under the influence of acetaminophen and negative photos were not seen as negatively.

The same could be said of their emotional reactions to the photos.

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

For example, people who took the placebo rated their level of emotion relatively high (average score of 6.76) when they saw the most emotionally jarring photos - the malnourished child or the children with kittens.

People taking acetaminophen didn't feel as much in either direction, reporting an average level of emotion of 5.85 when they saw the extreme photos.

While this study does not establish a cause-and-effect relationship, it does suggest a link between acetaminophen and our ability to feel certain emotions.

Acetaminophen is the most common drug ingredient in the United States, found in more than 600 medicines, according to the trade group Consumer Healthcare Products Association (CHPA).

Each week about 23 percent of American adults (about 52 million people) use a medicine containing acetaminophen, the CHPA reports.

At this point, researchers aren't sure if other common pain relievers such as ibuprofen and aspirin have the same effect. However, it warrants further research.

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