Alcohol can cause symptoms of arrhythmia, and, even at moderate intakes, increases the risk of atrial fibrillation, research shows. Caffeine does not promote ventricular arrhythmia, unless consumed in very high doses. A 25-year-old woman with a preexisting condition died after drinking 50 mL of a “natural energy” guarana health drink that contained the same amount of caffeine as 8 cups of strong coffee.