EVIDENCE LIBRARY
Can Energy Drinks Improve Some Alcohol-Affected Test Scores Without Restoring Driving Ability?
A 28-person crossover trial found partial improvements in some laboratory measures when an energy drink was added to alcohol. It did not demonstrate restored driving ability or complete reversal of alcohol effects.
Yes. Some laboratory performance measures can improve when an energy drink is added to alcohol without establishing that driving ability has returned to normal. In a controlled 28-person trial, selected vigilance and tracking outcomes improved relative to alcohol alone. Energy drinks did not fully offset alcohol’s effects, and the study did not measure actual driving.
The distinction matters in DUI interpretation: improvement relative to an alcohol condition is a different finding from recovery to a sober baseline, and both are different from proof of safe driving.
A four-condition crossover
Hladun and colleagues studied 14 men and 14 women in randomized, double-blind sessions involving alcohol plus energy drink, alcohol plus energy-drink placebo, energy drink plus alcohol placebo, and both placebos.
Men received 70 g of ethanol and women 55 g. The energy-drink quantities were 750 mL and 589 mL, containing approximately 240 mg and 189 mg caffeine, respectively. Beverages were divided across an 80-minute administration period. The different doses aimed to produce similar exposure between the groups rather than compare equal amounts consumed.
Mean peak breath alcohol with the combined beverages was approximately 0.46 mg/L in both groups. Alcohol was measured in breath; caffeine and taurine were measured in plasma. The study did not directly measure blood ethanol.
What improved, and what did not
The performance tests included a psychomotor vigilance task and a joystick tracking task. The tracking task displayed vehicles and lanes on a computer screen, but it was not a road-driving evaluation or a full driving simulation.
Adding the energy drink reduced some reaction-time outcomes compared with alcohol alone. For example, the integrated reaction-time effect over the tested period was lower in both men and women. Some tracking-error comparisons also favored the combined drink, particularly in men.
The pattern was incomplete. Not every measure or comparison improved, and alcohol-related effects remained. A significant benefit relative to alcohol alone therefore does not mean the combined condition was equivalent to placebo across all functions.
There were also no significant differences between men and women in the principal driving-related skill outcomes. Some dose-adjusted comparisons showed trends, which should not be promoted to confirmed differences. With only 14 participants in each group, the null comparisons did not establish equivalence.
Why the interaction analysis matters
The factorial design allowed the investigators to distinguish an energy-drink effect from an alcohol-by-energy-drink interaction. They did not find a significant interaction for the performance outcomes.
Thus, a faster response with the combined drink should not automatically be described as evidence of a specific biological neutralization of alcohol. An energy drink can influence a task score while alcohol continues to influence other aspects of performance. The absence of a significant interaction also does not prove that interactions are impossible at other doses or in other populations.
Feeling drunk and willingness to drive were separate outcomes
Women reported more integrated drunkenness and sedation on some comparisons with alcohol alone, despite similar peak breath concentrations. Those subjective differences did not translate into a demonstrated sex difference in the tested performance outcomes.
The energy drink did not significantly reduce reported drunkenness compared with alcohol alone. Nor did the study demonstrate a significant combined-versus-alcohol difference in its main subjective capability-to-drive or willingness-to-drive comparisons. It would be inaccurate to borrow an increased willingness finding from another study and attribute it to this trial.
The site’s SAFE trial analysis addresses the distinct question of how self-estimated driving fitness relates to breath alcohol.
Concentration changes did not establish sobriety
Across the analysis, adding the energy drink produced a small reduction in integrated breath-alcohol exposure, without a significant difference in peak alcohol within each sex. Plasma caffeine exposure was higher when alcohol accompanied the energy drink. These findings concern separate analytes and pharmacokinetic quantities.
A small AUC difference is not proof of complete alcohol removal, and a plasma caffeine concentration is not a measure of blood ethanol or driving impairment.
Limits on a DUI conclusion
The participants were young, healthy, accustomed to caffeine and had binge-drinking experience. The experiment used one energy-drink formulation, selected doses and controlled conditions. Some male placebo performance data were excluded as outliers, so not every comparison had an identical denominator.
The strongest conclusion is that partial task improvement can coexist with residual alcohol effects. The findings do not provide a safe mixing strategy, an individualized impairment cutoff or proof of crash causation. The site’s laboratory calibration analysis explains why driving prediction requires evidence beyond a sensitive test score.
Primary source
Hladun O, Papaseit E, Poyatos L, et al. No significant gender differences in driving-related skills following alcohol mixed with energy drinks during an experimental binge-drinking episode. Frontiers in Pharmacology. 2025;16:1581229. https://doi.org/10.3389/fphar.2025.1581229.