"There is evidence that the combinations of caffeine and alcohol in these products pose a public-health concern," Dr. Joshua M. Sharfstein, FDA principal deputy commissioner, said in a written statement.

FDA officials say consuming beverages that mix caffeine and alcohol masks a person's ability to determine how drunk they are.

Four Loko is a fruit-flavored alcohol-and-energy drink conceived in 2005 by Ohio State University graduates Chris Hunter, Jason Freeman and Jeff Wright. Sold for $2.50 apiece, each 23.5oz can contains 12% alcohol.

That 12%, or 2.82oz of pure alcohol, is equivalent to almost five beers, said Aaron White, a researcher at the National Institute on Alcohol Abuse and Alcoholism.

Mixed with 260mg of caffeine in each can -- or the equivalent of two to three cups of coffee -- Four Loko offers a stimulant/depressant mix stronger than other mixed drinks.

"It's one thing to have a couple beers and then have a cup of coffee after; it's a different thing to have three or four cups of coffee and then have three or four beers at the same time."

Previously, Phusion Projects had announced it is dropping stimulants caffeine, guarana and taurine from Four Loko amid efforts in multiple states to ban the latest alcohol-energy drink hybrid.

The FDA warning letter acknowledged the company's announcement, calling it a "positive step."

"We're pleased that the FDA commended us for our decision to reformulate our products nationwide," Hunter, Freeman and Wright said in a statement. "We have stopped the production and shipment of all our products containing these ingredients."

Despite agreeing to strip Four Loko of three of its primary ingredients, the drink's creators insist that it is no more dangerous than other commonplace libations.

"We have repeatedly contended -- and still believe, as do many people throughout the country -- that the combination of alcohol and caffeine is safe," they said in the statement.

"If it were unsafe, popular drinks like rum and colas, or Irish coffees, that have been consumed safely and responsibly for years would face the same scrutiny that our products have recently faced."

However, medical experts contend that the unique cocktail of stimulants found in an energy drink is especially dangerous when mixed with alcohol.

"What's different about other mixed drinks that include caffeine is that they are not likely to have the 'energy blend' found in energy drinks," said Nicole Pennington, director of nursing at Ohio University's campus in Ironton.

The mixture, she said, keeps college students awake longer, which allows them to get more intoxicated. Public officials in various states have called for bans on the drink.

The FDA also warned the makers of Moonshot, a beer brand with added caffeine, and alcohol-energy mixes Joose and Core.

From the November 29, 2010, Prepared Foods E-dition