Move over, Red Bull, Monster Energy and Rock Star. Some people now use powdered caffeine as an alertness boost for studying, sports or other activities. But the potent powder -- sold online as Extreme Sport Beans, Cracker Jack'd , MiO Energy and Alert Energy -- could be risky. A teaspoon is equivalent to 25 cups of coffee. A federal warning follows the death of a healthy 18-year-old Ohio varsity wrestler who consumed the pure stimulant.

The Food and Drug Administration is investigating caffeine powder and will "consider taking regulatory action," it says. The product is marketed as a dietary supplement and is unregulated, unlike caffeine added to soda. Parents should know, the agency adds, that some teens add the powder to beverages, sprinkle it on food or chew jellybean-like Extreme Sport Beans before a gym workout or late-night schoolwork.

Some brands explain the risks. Hard Rhino's label suggests using just one-32th to one-16th of a teaspoon to avoid serious harm. "This is PURE CAFFEINE and a little goes a long way," it reads.

Government says: "The difference between a safe amount and a lethal dose of caffeine in these powdered products is very small." – Jennifer Dooren, Food and Drug Administration spokeswoman

Doctor says: "I can't believe you can buy this. . . . It's frightening. It makes no sense to me." – Dr. Henry Spiller, head of poison control center at Nationwide Children’s Hospital in Columbus, Ohio

Caffeine overdose signs: Rapid or erratic heartbeat, seizures, vomiting, diarrhea and disorientation.