You’re tired and thinking that an energy drink will do it? Maybe you need to think twice before having one. At least this is what researchers at Johns Hopkins University in Baltimore, Md, concluded in a study published this week in the journal “Drug and Alcohol Dependence.” More exactly, the researchers said that energy drinks contain so much caffeine that they should carry labels warning consumers about it.

Energy drink market exploded after Red Bull first launched in 1997, now totaling at least $5.4 billion a year in the US. Since then, hundreds of brands have become available making people believe they can skip sleep hours because an energy drink will help them stay awake as much as needed. Teenagers of course are among those considering energy drinks a rescue. According to a 2007 survey of 496 college students, 51 percent said they had consumed at least one energy drink during the past month.

Researchers at Johns Hopkins University led by Dr. Roland Griffith contacted more than two dozen makers of energy drinks, asking for caffeine content. What they found should make anyone forget about having energy drinks the next time when feeling like having one. To be more specific, the researchers found that some drinks have up to 14 times the caffeine of a regular can of soda – which is the equivalent of downing 14 cans of coca-cola or seven cups of extra-strong coffee.

“The caffeine content of energy drinks varies, yet the amounts are often unlabelled and few include warnings about the potential health risks,” Dr. Griffith wrote in the paper.

According to the National Institutes of Health, moderate caffeine intake is defined as three 8 oz. cups of coffee per day while excessive intake as ten 8 oz. cups of coffee per day. Just to make some idea of the caffeine content of energy drinks, the study gives us some examples: Red Bull contains 80 milligrams of caffeine per 8.3-ounce serving; Tab Energy - 95 mg per 10.5-oz serving; Monster and Rockstar – 160 mg per 16-oz serving; No fear – 174 mg per 16-oz serving; Fixx – 500 per 20-oz serving and Wired X505 – 505 mg per 24-oz serving.

On the other hand, brewed coffee contains 200 mg per 12-oz serving, instant coffee – 140 mg per 12-oz serving, Pepsi Cola – 35 mg per 12-oz serving, Mountain Dew – 54 mg per 12 oz serving and Cola-Cola Classic – 34.5 mg per 12-oz serving.

The National Institutes of Health informs people they can face rapid heart rate, nausea, vomiting, restlessness, anxiety, depression, tremors and difficulty sleeping once they are consumers of energy drinks. In fact, Dr. Griffith said bad reactions to energy drinks have been reported to US poison control centers. From 2002 to 2004, there were reported 41 cases of caffeine abuse from caffeine-enhanced beverages.

The energy drinks that contain caffeine are marketed as supplementary (and not soft) drinks, therefore they are neither required to comply with the United States Food and Drug Administration’s maximum caffeine content for soda and other beverages (71 milligrams per 12-ounce can), nor compelled to label it.

This situation makes people more vulnerable to the risks carried by energy drinks. Hopefully, this study will make them more aware of that. Hopefully, health authorities will come with measures to prevent caffeine abuse in the future.