According to research energy drinks which are very popular and widely consumed have much more caffeine than a cup of coffee contains. What's more is that the caffeine in combination with other ingredients of these energy drinks along with alcohol is raising a lot of health concerns.

The content of caffeine is present in these drinks is available in ranges between 70 to 200 mg per 16-oz serving which when compared to a cup of coffee has higher amounts as an 8-oz cup of coffee contains between 40 to 150 mg depending on its brewing time and procedure.

John Higgins of the University of Texas Medical School at Houston, who led a study that appeared in this month's Mayo Clinic Proceedings said, "What we know is that a typical energy drink can have as much as a quarter cup of sugar, and more caffeine than a strong cup of coffee."

Most of the harmful ingredients are not even mentioned on the labels of these drinks like a stimulant guarana, the amino acid taurine and other minerals and vitamins which may have some bad effect in combination with caffeine.