So-called "energy" drinks containing caffeine and taurine should not be used as thirst-quenchers or mixed with alcohol, the Swedish National Food Administration said on July 12.
A group of doctors is investigating reports that such concoctions may have caused one death in Sweden.
Newspaper reports have linked three deaths possibly to consumption of the popular drinks.
According to Anders Glynn, the head of toxicology at the National Food Administration, about 70 energy drinks containing levels of caffeine or taurine in higher amounts than found in some soft drinks, juices and other beverages, have been approved for sale in Sweden.
The drinks are controversial.
Red Bull, for example, is banned for sale in neighbouring Norway and Denmark.
"A group of doctors will investigate a possible connection between so-called energy drinks mixed with alcohol and at least one death," Glynn said.
According to some doctors, caffeine in high doses can cause heart palpitations, breathing problems and even death.
The National Food Administration in 1996 allowed the sale of energy drinks with high levels of caffeine provided the cans were labelled with the warning, "Children, pregnant women and people sensitive to caffeine are advised not to use this drink."
According to Glynn, one can of energy drink contains about as much caffeine as a cup of coffee.
In 1999 the administration said there was no proof that taurine, an amino-acid, was harmful, but neither could it be proved that it was safe if used for a longer period in high doses.
According to Swedish media reports, two people died after drinking energy drinks mixed with alcohol, and a third person died of renal failure after working out and then drinking an unknown number of cans of energy drink.
"Meanwhile, we recommend that energy drinks should not be used together with alcohol or as thirst-quenchers when in lack of fluids," he added.