Before consuming the drink (and then again 20 minutes after), each participant completed an "Alcohol Urge Questionnaire" that assessed his or her craving for alcohol; BACs were also measured both pre- and post-drink. In the words of the researchers, those participants whose cocktails contained Red Bull reported higher levels of "liking the cocktail and wanting to drink more" than did those who were drinking just soda, vodka, and "fruit drink." What's more, the drinkers who had thrown back Red Bull and vodka actually had lower BACs than those who had vodka and soda. But, the study didn't control for gender, genetics, food consumption, body weight, or body composition — all factors that influence BAC. Still, researchers theorize that certain additives in energy drinks change the way the body metabolizes alcohol.
What is clear is that one energy drink-liquor combination is likely to lead to another, as stimulating energy drinks "cancel out" the sedating effects of alcohol, a depressant — meaning that when you're drinking both at the same time, your body won't tell you when it's time to give it up and go home. (That's what friends are for, right?) While these findings may not change your drink choices, now you'll know exactly what’s going on the next time you order a second — or third — vodka with Red Bull.