A lawmaker who has led a campaign to have drinks that combine the two elements outlawed said that the US food and drug watchdog is poised to ban caffeine in alcoholic beverages.
Senator Charles Schumer of New York said in a statement posted on his website that the Food and Drug Administration (FDA) is on the brink of ruling "that caffeine is an unsafe food additive to alcoholic beverages."
The ruling would effectively bar from sale in the United States drinks such as Four Loko, which combines alcohol, caffeine, the stimulant guarana and taurine in what Schumer called a "dangerous and toxic drink."
The drinks are marketed mainly toward young people, said Schumer, who has been leading a campaign in New York to have the beverages banned because of what he says are serious risks to health and safety.
According to Schumer, a can of a drink like Four Loko -- named because of its four main ingredients and with a play on the Spanish word for "crazy" -- contain as much caffeine as in two to three cups of coffee and as much alcohol as two to three cans of beer.
Last month, nine students passed out and were hospitalized after drinking Four Loko, leading several states and universities across the country to ban or issue warnings about drinks that mix alcohol and caffeine, Schumer said.
In New York, state-run liquor stores have stopped selling the energy-alcohol concoctions, which have also been banned in Michigan, Oklahoma, Utah and Washington and on a number of college campuses.
FDA spokeswoman Pat el-Hinnawy told AFP that the agency has spent nearly a year studying "the very important issue" of drinks that blend caffeine and alcohol, but refused to comment on whether a decision that would effectively ban the drinks was imminent.
Schumer's announcement came as a study of more than 1,000 US students showed that drinking caffeinated energy drinks on a regular basis significantly increases the risk of becoming alcohol-dependent and engaging in bouts of heavy drinking.