US regulators on Friday warned against ingesting pure powdered caffeine, which is being sold in bulk over the Internet and is known to have killed at least one teenager.
"These products are essentially 100 percent caffeine. A single teaspoon of pure caffeine is roughly equivalent to the amount in 25 cups of coffee," the Food and Drug Administration said.
The FDA advised consumers "to avoid powdered pure caffeine" and warned parents that teenagers and young adults may be drawn to it for its perceived benefits.
"Pure caffeine is a powerful stimulant and very small amounts may cause accidental overdose," the FDA statement said.
Symptoms of overdose may include rapid heartbeat, seizures, vomiting, diarrhea, stupor and disorientation.
"It is nearly impossible to accurately measure powdered pure caffeine with common kitchen measuring tools and you can easily consume a lethal amount," the FDA added.
US media reported earlier this month that an 18-year-old from Ohio died due to a caffeine overdose. Several bags of the powder were found in his home.
Consumer groups said regulators must take more action against the products.
"The overuse and misuse of caffeine in the food supply is creating a wild-west marketplace, and it's about time the sheriff noticed and did something," said the Center for Science in the Public Interest.