Although the US Food and Drug Administration (FDA) limits the amount of caffeine that can be in soda to 0.02 percent, there are no such limits for energy drinks. Despite the inherent lack of regulation, the sales of energy drinks have more than doubled in the past five years.
Energy drinks on average contain the same amount of caffeine per ounce as a cup of coffee. However, energy drinks are typically sold in 24-ounce cans (a common coffee cup holds 8 ounces).
Consuming caffeine in large quantities can pose several heath risks – in particular for children and people with pre-existing heart conditions. Too much caffeine can impair sleep cycles, cause anxiety, and increase the risk of dehydration. The consumption of caffeine also raises heart rate and increases blood pressure.