A concentrated form of powdered caffeine -- 1 teaspoon equals 25 cups of coffee -- is becoming popular among young people seeking an energy boost, but it can kill, according to William Eggleston, PharmD, a pharmacist at the Upstate New York Poison Center. Unregulated and sold cheaply over the Internet, the powder has been linked to two deaths and carries a high risk of accidental overdose, since 3 or 4 teaspoons is enough to kill an average adult.