CHICAGO

More than 500 new energy drinks launched worldwide this year, and coffee fans are probably too old to understand why.

Energy drinks aren't merely popular with young people. They attract fan mail on their own MySpace pages. They spawn urban legends. They get reviewed by bloggers. And they taste like carbonated cough syrup.

Vying for the dollars of teenagers with promises of weight loss, increased endurance and legal highs, the new products join top-sellers Red Bull, Monster and Rockstar to make up a $3.4 billion-a-year industry that grew by 80 percent last year.

Thirty-one percent of U.S. teenagers say they drink energy drinks, according to Simmons Research. That represents 7.6 million teens, a jump of almost 3 million in three years.

Nutritionists warn that the drinks, laden with caffeine and sugar, can hook kids on an unhealthy jolt-and-crash cycle. The caffeine comes from multiple sources, making it hard to tell how much the drinks contain. Some have B vitamins, which when taken in megadoses can cause rapid heartbeat, and numbness and tingling in the hands and feet.

But the biggest worry is how some teens use the drinks. Some report downing several cans in a row to get a buzz, and a new study found a surprising number of poison-center calls from young people getting sick from too much caffeine.

"Wow, this drink is some serious stuff. I mean about half the bottle is the warning label, and it is serious, this drink is INSANE. It says that you should not drink it unless you are over 18, which I would say is a good warning." - From a review of an energy drink by Dan Mayer on his Web site, www.bandddesigns.com/energy.

Danger only adds to the appeal, said Bryan Greenberg, a marketing consultant and an assistant professor of marketing at Elizabethtown College.

"Young people need to break away from the bonds of adults and what society thinks is right," he said. They've grown up watching their parents drink Starbucks coffee, and want their own version.

Heart palpitations aren't likely to scare them off.

Most brands target male teens and 20-somethings. Industry leader Red Bull, the first energy drink on the market, is now the "big arena band" of the bunch "teetering on the edge of becoming too big and too corporate," Greenberg said.

"Monster is more of a hard rocker, maybe with a little punk thrown in, much more hard-core," he said. "Rockstar is the more mainstream, glam rock band that's more about partying then playing."

(Monster is produced by Corona-based Hansen Natural Corp., and Rockstar, distributed by Coca-Cola Co., is made by Las Vegas-based Rockstar Inc.) Greenberg said the fierce competition among hundreds of new drinks, with Austria-based Red Bull guarding the biggest market share, leads to a "ratcheting up" of taboo names as companies try to break out from the crowd.

Cocaine Energy Drink, which launched in September and now sells in convenience stores and nightclubs in six states, is the latest example, following a twisted logic set by drinks named Pimpjuice and Bawls.

Hannah Kirby of the Las Vegas company behind Cocaine Energy Drink said Greenberg has it right. Kirby and her husband, Redux Beverage founder James Kirby, wanted to call their drink by the ho-hum name Reboot. That name was taken, so they decided to get provocative.

They're getting the attention they craved, along with some canceled orders. Following complaints from parents, convenience store operator 7-Eleven Inc. recently told franchises to pull the drink from its shelves.

"We knew we would get noticed against a thousand other energy drinks," she said. "We knew kids would find it cool, but we also wanted to stress the idea that it's an energy drink, you don't need drugs." Their slogan is "The Legal Alternative."

The Kirbys are parents of an 18-year-old son, Kirby said. The boy grew up hearing he shouldn't drink energy drinks on a school night.

"Cocaine looks so freaking tight. I NEED THIS STUFF. Next weekend, me and 3 friends are going to take a 6 hour road trip to NYC just to get our hands on this stuff."

- From a comment on the MySpace page of Cocaine Energy Drink.

Red Bull founder Dietrich Mateschitz based his product on tonics sold in Asia. He started selling Red Bull in 1987 in Austria, his native country, and today 2.5 billion cans are sold a year in more than 130 nations. The industry leader grabbed more than 37 percent of the U.S. market last year, according to Beverage Digest.

Rumors have swirled around Red Bull for years. Contrary to hearsay, the ingredient taurine (an amino acid important in making bile to aid digestion) is not made from bull urine, and Mateschitz did not learn about Red Bull from rickshaw drivers in Thailand. The urban legends-debunking Web site www.snopes.com has a page devoted to exposing the false claim that Red Bull contains a banned substance linked to brain tumors.