Energy drinks are beverages which contain large doses of caffeine and other legal stimulants such as guarana and ginseng. The amount of caffeine in an energy drink can range from 6 milligrams to over 500 milligrams per serving. This compares to 34 milligrams in Coca-Cola and 54 milligrams in Mountain Dew. For more information on caffeine content of energy drinks and similar products, click here. If a drink advertises no caffeine, the “energy” typically comes from guarana and other stimulants, very similar to caffeine or actually containing derivatives of caffeine.