Some researchers say energy drinks should have a warning label.
The drinks are not required to list their amount of caffeine... But scientists at Johns Hopkins University School of Medicine say some drinks contain 14-times the amount of caffeine than a regular soda.
Caffeine can lead to rapid heart rate, nausea, anxiety, and in some people sensitive to caffeine, it can cause heart problems.
Most energy drinks list their amount of caffeine on their website, but not on the can.
The Institute for Good Medicine at the Pennsylvania Medical Society is also taking aim at these popular beverages on a new web show called Good Medicine.
During the three-minute-plus show, Dr. Peter Lund, founder of the Institute for Good Medicine, describes what energy drinks are, and then focuses on the levels of caffeine that in part make these drinks controversial.
He also discusses research data on energy drinks from The Patient Poll, a survey tool by the Institute for Good Medicine that measures the pulse of the public's expectations and knowledge of health care issues.
