ABC News spoke to men and women in energy beer's target demographic and asked them to taste two brews from the genre -- Anheuser-Busch's BE and Tilt.
None of the testers had sampled energy beer before -- some hadn't even heard of the hybrid -- and many expressed reservations about mixing caffeine with the depressants in alcohol.
"It doesn't seem right," Kulkarni said. "It's like asking your body to do two different things."
According to George Hacker, director of alcohol policies at the Center for Science in the Public Interest, such fears are not unfounded.
"These beverages counteract the dulling effects of alcohol, but they don't counteract the intoxicating effects of alcohol," Hacker said. "They promote heavier drinking by making people think they're more alert and capable than they actually are. The caffeine certainly could have negative effects."
Health concerns aside, our testers' opinions on energy beer were about as mixed as the average cocktail. After a sip of Tilt, one dubbed the drink "very tasty," while another grimaced as he choked down the fluorescent orange liquid.
Asked whether they preferred BE or Tilt, most testers opted for the "like beer but sweeter" BE. But given the choice between the caffeine-enhanced malts and regular beer, almost all opted for traditional ale.
Despite the quick growth, some experts hesitate to tout energy beer as the next big thing.
"Sparks has been a very hot brand," said Beer Marketer's Insights' Shepard. "Does that mean we're all going to be consuming this very soon? I don't know -- I wouldn't predict."
But most agree that brewers will continue to come out with nontraditional beers featuring flavors and ingredients beyond the basic.
"They're putting new things out there to see what different consumers might be interested in -- organic beer, malt-based beers targeted at females," said Sarah Theodore, editor of the trade publication Beverage Industry. "They're going after specific consumer segments and not necessarily taking a one-size-fits-all approach."
Beer makers hope that by expanding their range of offerings, they can win over drinkers partial to hard liquor or wine.
In a written statement, Anheuser-Busch vice president Andy Goeler said: "Consumers expect choices, and we continue to increase the range of popular beers and beverages we offer. Caffeinated beers are only one example. ... We will continue to take cues from adult alcohol beverage drinkers to ensure, no matter the drinking occasion, we have something for everyone."
But the move to produce more energy beers and entice young drinkers concerns Hacker.
"The emphasis on concocting whatever it takes to attract new taste buds to beer is something we find very troubling," he said. "This creativity has all to do with beer makers' bottom line and very little to do with public health and safety."
In the end, what beer drinkers think of these nontraditional brews will determine whether they sit on store shelves or get tapped in bars. Indeed, some taste buds are very happy with the traditional brew that's stood the test of time.
Said Dong Lee, one of the entry-level drinkers who sampled Tilt: "It's OK. But it's not beer."