In a recent study, researchers found the 1,000-milligram maximum standard dose of acetaminophen, most widely known as Tylenol, appeared to cause cognitive impairment among people treated with the drug. Photo by Niloo/Shutterstock

TORONTO, April 8 (UPI) -- Acetaminophen, commonly sold as Tylenol, is thought to treat everything from fever to headache with few or no side effects, but a recent study suggests the drug could prevent people from spotting errors.

Researchers at the University of Toronto found people are less reactive to uncertain situations when they've taken normally recommended doses of the drug.


Acetaminophen is used by a lot of people without prescription, and the recent study showed people did not perceive any cognitive difference while on the drug, but that doesn't mean it isn't there.

While recent research has only begun to show how acetaminophen stops pain, some behavioral studies have shown slight cognitive impairments when on the drug. Researches involved with the new study conducted previous research that found slower reactions among participants using acetaminophen.

"An obvious question is if people aren't detecting these errors, are they also making errors more often when taking acetaminophen?" Dan Randles, a researcher at the University of Toronto, said in a press release. "This is the first study to address this question, so we need more work and ideally with tasks more closely related to normal daily behavior."

For the study, published in the journal Social Cognitive and Affective Neuroscience, researchers recruited 62 people for a double-blind, randomized study with half the participants receiving 1,000 milligrams of acetaminophen, the normal maximum dose, and the rest given a placebo.

The participants were then hooked up to an electroencephalogram and given a target-detection task called Go or No Go, hitting a button when an "F" appeared on a screen but not hitting the button if an "E" appeared on the screen.

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In addition to hitting the button more often when an "E" appeared, the group given acetaminophen also missed more "F" screens than the placebo group -- suggesting the drug has an effect on the mind beyond simply killing pain.

"It looks like acetaminophen makes it harder to recognize an error, which may have implications for cognitive control in daily life," Randles said.