Knoxville (WVLT) - They compete for teenage consumers with promises of weight loss, increased endurance and legal highs.
In fact, the energy drink industry grew by more than 80 percent last year.
Medical Reporter Jessa Goddard is covering your health with the dangers of a "wired generation."
You could call it Starbucks for kids.
With the amount of caffeine in energy drinks, they are essentially a legal form of speed.
Many young people drink them to stay awake, and many others drink them in excess to get high, resulting in a caffeine overdose and ending up in the emergency room.
Energy drinks contain, on average, two to four times the amount of caffeine as that of Coke.
And seven teaspoons of sugar.
"And one thing we know is it stays in a child's body generally longer than it does in an adult, even up to 24, even 30 hours in very young children," says Dr. Randy Pardue.
The primary ingredients in energy drinks are caffeine and taurine, but most don't tell you how much.
Energy drinks can hook kids on an unhealthy crash and jolt cycle.
The caffeine can come from many different sources, some contain B vitamins, for example, which when taken in high doses can cause rapid heartbeat, and numbness in the hands and feet.
And family practice Doctor Randy Pardue says these drinks are not regulated by the food and drug administration.
"And there really is a caffeine overdose syndrome where they can get twitchy, more of a buzz, extremely hyperactive," says Pardue.
Though some small studies have shown those who consume energy drinks in moderation experienced improved aerobic endurance and recalled numbers better, another study found it had no effect on memory, but did improve attention and verbal reasoning.
Doctor Pardue says, the truth is no one really knows what kind of effect these drinks can have. "I would say first of all, it hasn't been studied real well, so I think there are a lot of unknowns there."
In the meantime, energy drinks are moving toward bigger cans and higher caffeine content.
Some energy drinks contain mega-doses of some vitamins, unnecessary nutrients and more caffeine than plain sodas that can give you a fast up-and-down sugar high and a rough caffeine buzz.
And, drinking two or three cans a day for a period of weeks or months might trigger some side effects from these vitamin mega-doses.