How could too much caffeine kill?

See below: Caffeine is a drug ; although it is present in coffee (among other food products) it should be used cautiously ; in moderation. The exact mechanism is debatable, but large doses of caffeine can cause cardiac arrhythmia leading to cardiac arrest. It is recommended that energy drinks that have excessive caffeine be avoided ; rather try to regularize your sleep so you're not tired in the mornings.