If you’ve just popped a few Tylenol to ease a headache, be extra careful crossing the street.
Here’s why: The popular analgesic doesn’t just ease pain. It also dulls “evaluative processing”—your ability to notice something out of place (i.e., incorrect) in routine activities that you perform on “autopilot.”
Acetaminophen, the active ingredient, is already known to have some unusual cognitive effects—it dulls the feeling of distress from social rejection, for instance. So researchers at The University of Toronto wanted to see if the drug might have a more widespread “blunting” affect.
To test their theory, they gave about 30 men and women a placebo, and another group of 30 a normal maximum dose of acetaminophen—1,000 mg, which is what you’d get if you took two extra-strength Tylenol. The researchers hooked up the participants’ brains to EEG machines and gave them a fast-paced computer task designed to mimic the kind of autopilot we normally lapse into when doing routine or repetitive tasks.
Results: Compared with the group that didn’t take the drug, the acetaminophen group failed to notice deliberate errors that were part of the computer task…and showed less activity in a part of the brain that normally lights up when you realize that you’ve made a mistake. In other words, the drug not only made them less aware of errors but reduced their ability to evaluate their actions…to realize when they’re off their game.
This skill is important. According to study author Dan Randles, PhD, a postdoctoral fellow at the university, “Sometimes you need to interrupt your normal processes or they’ll lead to a mistake. When you’re talking to a friend while crossing the street, for example, you should be ready to react to an erratic driver.”
BE CAREFUL WITH ACETAMINOPHEN
More research is planned to investigate implications raised by this study, including whether acetaminophen also causes people’s minds to wander and to actually make more mistakes—not just fail to notice them.
But there are already good reasons, such as the risk for liver toxicity, to limit the amount of acetaminophen you take in a day. A good rule of thumb—stick to no more than 2,000 mg a day max, even if the label tells you that more is OK. Limit alcohol to one or two drinks, since the combination can greatly increase the risk for liver toxicity…and be careful about combining with coffee, too. Also, watch out for accidental overdoses, since the drug shows up in many over-the-counter medications. You may also want to explore drug-free ways to ease pain in your back, joints, head and muscles.
And if you do take a couple of extra-strength Tylenol capsules, be sure to focus more closely on tasks that require detailed attentions—and stay alert to what’s going on around you when you’re crossing the street or driving.