Some people believe that both the Aspartame and Caffeine can cause problems like this however it has never been proven. One thing I can and will tell you is that if you overdose on caffeine meaning well over 300mg depending on the size and tolerance the body has, it can cause arrhythmias such as different types of tachycardia
and even ventricular fibrillation
. Let's be realistic though unless your chugging coffee and I mean 20 cups or so fairly fast this isn't an easy thing to accomplish.