You Asked:

Do energy drinks really work? — Joslynn, Trafalgar, Ind.

Marshall Brain Answers:

The answer to this question depends on what “really work” means. If it means “do energy drinks provide a short-term boost that helps keep people awake and feeling like the energizer bunny?”, then the answer is yes.

How do energy drinks create that effect? The most common ingredient for providing the boost is caffeine. As described in How caffeine works, caffeine mimics a chemical called adenosine, which makes people feel drowsy. Caffeine therefore replaces adenosine on receptor sites and eliminates the drowsy feeling. Energy drinks can contain a lot more caffeine than a normal soda of coffee would – so much that drinking too many energy drinks can cause overdose symptoms. This article points out that “400 mg of caffeine a day is the upper limit.”

As the marketplace for energy drinks has gotten more crowded, the drinks have started adding ingredients to make themselves unique. These ingredients can include everything from normal vitamins to exotics like Guarana seed (which is simply another source of caffeine). You can find more ingredients on this page and this page.

Sometimes the special ingredients go a little too far:

More info: How do energy drinks work?