The stimulants in most energy drinks can have potentially harmful effects on young people. Caffeine can cause nervousness, anxiety, insomnia, and gastrointestinal problems. At very high doses it can be toxic, causing tremors, seizures, rapid heartbeats, and in rare cases, death.
And it can be hard to tell how much caffeine is in an energy drink, because some manufacturers don't list the amount on the label. Some drinks have more than 500 mg of caffeine, equal to about 14 caffeinated soft drinks.
The sugar and acids in energy drinks can damage tooth enamel.