If caffeine weren't already in coffee and tea, it would be a forbidden drug. It is psychoactive and combined with sugar, you can get really cranked up to help you run up walls to the ceiling and run down the wall on the other side. And over and over and over and over, depending on just how much caffeine you've had.
Caffeine is toxic in high enough doses, somewhere in the range of 50-100 cups of coffee. So just switch over to Red Bull and diet soda after noon when you've hit your coffee limit to wash down your caffeine pills. Because if you don't you know you will just slow down and crash.