LogFAQs > #972625725

You also aren't really supposed to down them on a regular basis. A can here or there is fine, but you do need actual proper rest/sleep since there is such a thing as sleep debt you'll need to face.

For an all nighter or when you just need the pep it's fine. If it becomes two a day every day like it's nothing/regular over a long period, then I don't think the cost is going to be your biggest concern.