Acetaminophen, commonly known as paracetamol and sold under global brand names like Tylenol and Panadol, is one of the most widely consumed pain relievers in the United States. While it’s widely used to ease pain and reduce fever, new research suggests the drug may also have unexpected effects on the brain, particularly in altering how people assess and respond to risk.
The analgesic works by blocking chemical messengers in the brain that signal pain, but researchers now believe that in doing so, it may also dampen emotional responses and decision-making processes.
A 2020 study led by neuroscientist Baldwin Way of The Ohio State University examined how acetaminophen influences behavior and found notable changes. “Acetaminophen seems to make people feel less negative emotion when they consider risky activities—they just don’t feel as scared,” Way explained.
He added, “With nearly 25 percent of the population in the U.S. taking acetaminophen each week, reduced risk perceptions and increased risk-taking could have important effects on society.”
The research, which involved more than 500 university students, aimed to study risk-related behavior after a single, adult-recommended dose of acetaminophen. Participants were randomly assigned either acetaminophen or a placebo before taking part in a computerized balloon-pumping experiment.
In the test, each pump inflated a virtual balloon and earned participants imaginary money. If the balloon popped, they lost all their earnings. The goal was to earn as much money as possible without bursting the balloon.
Interestingly, the group that took acetaminophen pumped the balloons significantly more times than the placebo group—leading to more balloon bursts and more risky behavior overall.
“If you’re risk-averse, you may pump a few times and then decide to cash out because you don’t want the balloon to burst and lose your money,” Way said. “But for those who are on acetaminophen, as the balloon gets bigger, we believe they have less anxiety and less negative emotion about how big the balloon is getting and the possibility of it bursting.”
These results align with earlier studies that show acetaminophen may reduce empathy and blunt emotional responses. Previous findings have indicated the drug can lower sensitivity to others’ pain and reduce emotional reactivity, potentially impacting social behavior.
While the research suggests a link between acetaminophen and altered risk perception, Way noted that these psychological changes could also be interpreted more positively, perhaps by reducing anxiety and boosting confidence in decision-making.
Nonetheless, the findings raise important questions about the broader cognitive and emotional effects of one of the most commonly used medications worldwide.