Acetaminophen, the active ingredient in pain relievers like Tylenol, can have well-known physical side-effects. According to the National Institutes of Health (NIH), taking too much can damage your liver.
But new research suggests the drug also carries potential psychological side effects as well – effects that might be either positive or negative, depending on the person taking it.
Researchers at Ohio State University already knew from previous research that acetaminophen not only reduced physical pain but also psychological pain. But to what extent, they wondered?
In their study they showed very pleasant and very disturbing photographs to 2 groups of people. One group had taken acetaminophen, the other a placebo.
Blunts positive emotions
After reviewing the results, the researchers concluded the painkiller blunts positive emotions.
“This means that using Tylenol or similar products might have broader consequences than previously thought,” said Geoffrey Durso, the study's lead author.“Rather than just being a pain reliever, acetaminophen can be seen as an all-purpose emotion reliever.”
The mood changes, however, were subtle. Baldwin Way, an assistant professor of psychology at Ohio State and one of the authors, said most people taking the drug were not aware they felt any different.
“Most people probably aren’t aware of how their emotions may be impacted when they take acetaminophen,” he said.
Acetaminophen has been in use for about 70 years and is considered the most common drug ingredient in the U.S. The researchers cite an industry trade group in estimating it is found in more than 600 medications. About 23 million U.S. consumers take a drug each week containing acetaminophen.
Because of those large numbers, the researchers say consumers should be aware of the drug's psychological side effects, especially since those effects appear to be so subtle. But for people whose moods tend to bounce from high to low, those side effects might not be all bad.
“People who took acetaminophen didn’t feel the same highs or lows as did the people who took placebos,” Way said.
Not a substitute
But no one is suggesting that you replace your prescription anti-depressant with an over the counter painkiller. That kind of decision must be made by a clinician and it's doubtful any would recommend that step. And as mentioned earlier, there are physical dangers in taking too much acetaminophen.
Instead, the researchers believe the big take-away from their work is the possible impact on psychological theory. Way says psychologists are studying whether the same biochemical factors govern how people react to both positive and negative events.
He says the study offers support for a recent theory that says common factors may influence how sensitive we are to both the bad as well as the good things in life.
It's possible, Way says, acetaminophen may have tapped into the sensitivity that makes some people react differently to both positive and negative events in everyday life.