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Acetaminophen — known widely as paracetamol and sold under brand names like Tylenol and Panadol — is one of the most commonly used pain relievers on the planet. New behavioral research suggests this familiar over-the-counter medicine may alter how people feel about danger, nudging some toward greater risk-taking. The effects reported are subtle, but given the drug's ubiquity, they merit attention.
How a simple balloon game revealed changes in risk behavior
In 2020, neuroscientist Baldwin Way and colleagues at The Ohio State University published a series of experiments that tested whether a single, recommended dose of acetaminophen changed how participants judged and engaged with risk. More than 500 university students took part. Each volunteer was randomly assigned to receive either a 1,000 mg dose of acetaminophen (the usual maximum single adult dose) or a placebo, and then completed tasks designed to measure risk perception and risk-taking.
The best-known task in the study was the balloon analog risk task: participants pumped a virtual balloon on a computer screen. Each pump earned hypothetical money, but if the balloon burst they lost it all. Participants were told to earn as much as possible without popping the balloon.
Across experiments, students who had taken acetaminophen pumped more times and burst their balloons more often than those who received placebo. In short: under the drug, people took larger gambles. Way and co-authors suggested this could be because acetaminophen reduces the negative emotion or anxiety that usually accompanies escalating risk.
Perception vs. emotion: what exactly is changing?
The researchers used follow-up surveys to probe perceived danger in hypothetical real-world scenarios — for example, betting a day’s wages on a game, bungee jumping off a tall bridge, or driving without a seatbelt. In one survey acetaminophen users rated those scenarios as less risky than the control group did; in another, no difference was observed. Results across tasks painted a mixed yet consistent picture: the drug appears to blunt affective responses to risky choices, and that blunted affect can translate into riskier behavior.
"Acetaminophen seems to make people feel less negative emotion when they consider risky activities — they just don't feel as scared," Way said when the findings were released. The investigators point out that the effect sizes are small and that laboratory tasks do not perfectly map onto real-life choices. Still, with roughly a quarter of Americans reportedly using acetaminophen each week, even a modest shift in risk perception could have tangible public-health consequences.
A 3D molecule of acetaminophen
What the science says about mechanisms
Exactly how acetaminophen alters emotion and decision-making remains uncertain. Several lines of research hint that acetaminophen affects brain regions involved in affective processing — such as the anterior cingulate cortex and the insula — and may interact with serotonergic or endocannabinoid signaling. Other studies link common analgesics to reduced sensitivity to social pain and lower empathic concern, suggesting the drug dampens a range of negative affective responses, not only physical pain.
Alternative psychological explanations
- Reduced anxiety: If acetaminophen lowers anxious anticipation, people may feel less urgency to avoid potential losses.
- Blunted affective forecasting: The medicine might weaken how vividly people imagine negative outcomes — changing the emotional cost of risky choices.
- Cognitive effects: Some work suggests the drug can subtly influence cognitive functions that underpin decision-making.
Broader implications for public safety and policy
Because acetaminophen is an active ingredient in hundreds of over-the-counter and prescription products, understanding any behavioral side effects is important. The potential for marginally increased risk-taking could matter in contexts like driving, workplace safety, financial decisions, or emergency responses — places where reduced aversion to harm might change outcomes. Still, experts emphasize that these findings do not mean acetaminophen is unsafe when used as directed; rather, they underline a gap in our knowledge about how common analgesics shape emotion and behavior.
Research published in 2023 by the University of Vienna also linked liberal analgesic use to reductions in empathic concern and prosocial behavior, reinforcing the possibility that analgesics can influence social and affective processes outside purely physical pain relief.
Surveys asked participants to rate the level of risk in driving without a seatbelt. (shisuka/Canva)
What researchers want to test next
Future studies need to address several open questions: are effects dose-dependent or cumulative with repeated use? Which neurochemical pathways mediate the behavioral changes? Do effects generalize beyond young adult volunteers to older adults or people with chronic pain? And crucially, do small laboratory effects translate to meaningful changes in real-world risk outcomes?
Expert Insight
Dr. Elena Ruiz, a cognitive neuroscientist at the Global Institute for Behavioral Health, comments: "These findings are intriguing because they connect a familiar medication to subtle shifts in affective processing. If acetaminophen reduces the anticipatory anxiety that normally tempers risky choices, we need to study when and where that matters. For most routine uses it's probably not cause for alarm, but for high-stakes activities—driving long distances or operating heavy machinery—it's worth asking whether guidance should change."
Dr. Ruiz adds that longitudinal and mechanistic studies are the logical next step: "A small, well-controlled trial that tracks behavior after repeated dosing and maps brain activity would help clarify whether this is a transient, clinically irrelevant blip or a consistent influence on decision-making."
What you can take away
Acetaminophen remains an essential and widely used medicine. The emerging evidence linking it to modest changes in risk perception does not overturn its value for pain and fever relief. However, it does highlight the broader principle that drugs designed to relieve bodily symptoms can also alter emotion and judgment. For clinicians, patients and policy-makers, the prudent path is more research and awareness: better information helps people make informed choices about when to take analgesics and whether to avoid potentially risky activities soon after dosing.
Source: sciencealert
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