According to researchers from Johns Hopkins University in Baltimore, the energy drinks available on the market contain so much caffeine that they should have many warning labels on them, which, of course, they don’t. Some of the energy drinks contain 14 times the caffeine of a normal soda. This might the equivalent of 7 seven cups of coffee.

Dr. Roland Griffiths wrote in the journal Drug and Alcohol Dependence that "The caffeine content of energy drinks varies, yet the amounts are often unlabelled and few include warnings about the potential health risks.” These risks would be rapid heartbeat, nausea, vomiting, anxiety, depression, tremors and bad sleep.

The Food and Drug Administration has set a limit for the caffeine content of these soft drinks which was settled to 71 milligrams per 12-ounce can, but this doesn’t apply because the energy drinks are so-said the to be "dietary supplements." So one energy drink contains from 50 to 500 milligrams of caffeine.

Chad Reissig, one of the study's authors, said that "it's notable that over-the-counter caffeine-containing products require warning labels, yet energy drinks do not." Still, the researchers are concerned about the fact that these energy drinks could reach the status of abuse of drugs.

Almost $5.4 billion a year get the U.S. Hundreds of brands of energy drinks since Red Bull first appeared in 1997. This drink contains 80 milligrams per 8.3-ounce serving and another one called Tab Energy contains 95 mg per 10.0-oz serving. In comparison, brewed coffee contains 200 milligrams per 12-oz serving and instant coffee 140 mg per 12-oz serving. Still, Coca-Cola Classic contains only 34.5 mg per 12-oz serving.