Excessive cola drinkers beware, your daily fix could cause an irregular heartbeat muscle problems, or paralysis. Large quantities of cola can cause hypokalaemia which is is a condition where the levels of potassium in your blood fall to. By large, we are talking about two liters to ten liters daily (slightly more then half a gallon to slightly more then two and a half gallons). The condition appears fully reversible with potassium supplements and taking a break from your fix.
More at http://www.telegraph.co.uk/scienceandtechnology/science/sciencenews/5350530/Drinking-large-amounts-of-cola-can-cause-paralysis-doctors-warn.html.