Not just any energy drink; I drank an Extreme Energy™ 6-Hour Shot. According to the packaging, it's "The World's Most Extreme Energy Shot!" It contains many vitamins and herbs that are believed to be energy-enhancing, but it doesn't contain sugar.
According to the Website Energy Fiend, a 2 ounce bottle of Extreme Energy 6-Hour Shot contains 220 milligrams of caffeine, substantially more than the Diet Mountain Dew (55 milligrams) or Diet Pepsi Max (69 milligrams) that I usually drink when I need a cold pick-me-up.
The directions on the package said:
For maximum-impact rapid energy: Drink entire 2-oz bottle at one time. For optimal 6-hour duration: Drink contents of half the bottle and reseal. Drink the remainder three hours later.I was REALLY dragging, so I downed the entire bottle at once. It tasted similar to cough syrup, with a vaguely orange flavor followed by a nasty aftertaste that lasted until I chewed some gum.
The shot allowed me to function well for the rest of the afternoon (actually more than the stated six hours), and they were right-I didn't get a shaky sugar-crash feeling.