Before you crack open that next liquid stimulant in a can, know this: energy drinks can significantly increase heart contractions, putting strain on the muscle.
Researchers at the University of Bonn in Germany looked into the effects of drinks like Red Bull, Monster and Rock Star on our bodies and came up with some alarming results.
The study showed that energy drinks, which can sometimes pack three times the caffeine as coffee, can trigger palpitations, spikes in blood pressure and, rarely, seizures or cardiac arrest.
To get their results the researchers looked at the hearts of 15 men and three women with a 1.5-Tesla MRI scanner.
The volunteers were asked to drink a beverage with high amounts of caffeine and taurine, a key ingredient in energy drinks, and then had their hearts imaged again.
An hour after drinking the beverage, the volunteers showed increases in peak strain and peak systolic strain rates in the heart's left ventricle.
If you remember biology, that's the ventricle responsible for receiving oxygenated blood from the lungs.
That increased strain can be harmful to some.
Energy-drink makers claim that their products help with athletic ability but researchers aren't so sure.
"We don't know exactly how or if this greater contractility of the heart impacts daily activities or athletic performance," said the study authors.
"We need additional studies to understand this mechanism and to determine how long the effect of the energy drink lasts."
The Los Angeles Times reported that energy drinks have sent 21,000 Americans to hospital emergency rooms in 2011.
The study was presented on Monday at the annual meeting of the Radiological Society of North America.