Drinking few energy drinks per day is unlikely to kill you unless you have heart problems such as heart disease or you're at risk of heart attacks or strokes already.
But if you did drink enough energy drinks in a month or two then it could kill you but it would take several energy drinks such as 20 per day or more to kill you that quick.
Energy Drinks are safe to drink in moderation and can give you a boost in energy but you should avoid drinking too many energy drinks because they can cause heart problems and could lead to a heart attack or stroke.
The energy drinks can increase your heart beat rate which means that your heart will beat faster than normal which is not good if it does so too much.
When your heart beats too fast that increases your blood pressure when can then lead to heart attacks and strokes.
Your blood pressure needs to be at a normal rate for your heart and body to stay healthy and if it isn't then too much blood pressure can cause your heart to fail.
Your heart is a pump and valve for blood just like a cars oil pump and when it gets too much pressure it can damage your organs and blood vessels and even the heart can be damaged as a result.