In the wake of an FDA report citing 5-Hour Energy drinks in 13 deaths during the last four years (as well as news of deaths linked to Monster and Rockstar energy drinks), Forbes posts answers to FAQs in "What you really need to know about 5-Hour Energy drink."
Among the questions: "What's in these drinks?" Forbes says there are 160 to an estimated 242 milligrams of caffeine in energy drinks such as Monster, Rockstar and 5-Hour Energy. But some of the problems tied to energy drinks are not due to the caffeine, Forbes says; rather, they are related to phenylalanine, a potentially toxic amino acid.
Phenylalanine "cannot be adequately broken down by people with a genetic disorder called phenylketonuria," Forbes says. "In such individuals, the amino acid gets converted to a chemical that can cause seizures."
Forbes also points out that whatever else is in a person's system can interact with a high-caffeine supplement. Neuroscientists are concerned whether caffeine can increase the lethality of ecstasy, amphetamine and methamphetamine.