The U.S. Food and Drug Administration (FDA) has issued five warning letters to the distributors of pure powdered caffeine, citing two fatalities linked to caffeine toxicity as evidence that the products “are dangerous and present a significant or unreasonable risk of illness or injury to consumers.” Equating 1 teaspoon of pure caffeine to 25 cups of coffee, FDA also warns consumers not to purchase or use powdered caffeine as “it is nearly impossible to accurately measure pure powdered caffeine with common kitchen measuring tools and you can easily consume a lethal amount.”

In particular, the agency plans to “aggressively monitor the marketplace” for pure powered caffeine being sold as a dietary supplement. The warning letters not only find the products adulterated under the Federal Food, Drug, and Cosmetic Act, but argue that labeling directs consumers to use difficult measurements such as one-sixteenth of a teaspoon. “Consumers are unlikely to have a one-sixteenth teaspoon measuring tool, as this tool is not generally available in standard consumer measuring spoon sets,” FDA tells one company. “Even if such a tool were available, it would be difficult to use it to measure a 50 milligram serving of your product, as 50 milligrams is approximately one-quarter of a one-sixteenth teaspoon measuring tool based on the numbers on the chart you provided.”

As the agency’s letters conclude, “In light of the potential toxicity of your product; the fact that your product is packaged to contain an amount that would be lethal to many consumers; the fact that the packaging requires the consumer to separate out a safe serving from this potentially lethal amount; and the fact that the product labeling incorrectly implies that this process of separating out a safe serving from a potentially lethal amount can be done with certain common household measuring tools,when in fact it would require a precise scale; we have determined that your product presents a significant or unreasonable risk of illness or injury under the conditions of use recommended or suggested in the labeling.”