WASHINGTON — The Food and Drug Administration (FDA) is warning consumers to avoid pure powdered caffeine sold on the Internet after the death of an Ohio woman.

Even a teaspoon of the powder — which is equivalent to 25 cups of coffee — could be lethal. Logan Stiner, 18, of LaGrange, Ohio, died May 27 after consuming it.

The FDA said it is investigating caffeine powder and will “consider taking regulatory action.” In the meantime, the agency is recommending consumers stay away from it.

Teenagers and young adults may be particularly drawn to the powder, which is a stimulant. Caffeine powder is marketed as a dietary supplement and is unregulated, unlike caffeine added to soda.

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FDA spokeswoman Jennifer Dooren said those who drink coffee, tea or soda may be aware of caffeine’s less serious effects, such as nervousness and tremors.

“The difference between a safe amount and a lethal dose of caffeine in these powdered products is very small,” she said.

Jim O’Hara of the Center for Science in the Public Interest praised the FDA’s warning, but said the agency needs to go further to keep powdered caffeine off the market. It is available on Amazon.com and other sites.

“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,” O’Hara said of the FDA.