The American Association of Poison Control Centers has issued extensive warnings against excessive use of energy drinks, especially for adolescents. Red Bull reports that one 8.4-ounce can of original flavor Red Bull energy drink contains about 80 milligrams of caffeine.
While it is generally considered safe for adults to ingest caffeine in moderate amounts, the American Association of Poison Control Centers recommends no more than 100 milligrams per day for adolescents, which equals about a cup of regular coffee. One can of Red Bull is close to the same amount, so no more than a can would be recommended. Overuse could result in numerous side effects, including nausea, vomiting, tremors, mood changes and increased heart rate. At least one study has shown that more than one can of energy drink per day may be linked to diminished cognitive function as well.