HOLLYWOOD, Fla. (Ivanhoe Newswire) -- Energy drinks are a booming business. Americans spent 744 million dollars on them in one year alone. They’re already banned in several countries, including Denmark, Italy, Norway and Sweden, but in the U.S., the drinks are marketed to our youth. So what's the risk?

With names like rock star, red bull and monster, teens are drawn to energy drinks.

"I was really curious about them," Orin told Ivanhoe.

"I started drinking them because my friend was drinking them," Kathy explained to Ivanhoe.

18-year-old Ryan told Ivanhoe that he used to down eight energy drinks a day, "I'd come to school with like three or four, and by lunch, they'd be gone."

Doctor Peter Antevy says energy drinks are especially harmful to the still-growing teenage brain. "The FDA went ahead and approved these drinks with ingredients that have never really been looked at," Antevy, M.D., pediatric emergency room physician at Joe DiMaggio Children's Hospital in Hollywood, Florida told Ivanhoe.

An eight-ounce cup of coffee averages 85 milligrams of caffeine. One energy drink has up to 500 milligrams. "Imagine the high you get and the crash that ensues quickly after that," Peter Antevy, M.D. described to Ivanhoe.

Energy drinks also contain taurine, guarana, mega-doses of b vitamins and a potent "energy blend" -- all of which can increase heart rate. Doctor Antevy says the mixture can cause serious heart problems -- even death. Consuming too many energy drinks has also been linked to anxiety and high blood pressure.

"I think that these drinks should be banned in the U.S. They should not allow these companies to put that amount of caffeine in a drink," Antevy voiced his opinion.

Ryan kicked his habit after he clocked his resting heart rate at 117 beats per minute. A normal resting heart rate is between 60 and 100. "I was actually very scared. I thought I was sort of like having a heart attack," Ryan said.

Orin, Kathy and Mike know the risks, but they still drink them. "I'm not going to drink them for the rest of my life," Mike said.