With an ever-growing search for the next energy-drink-pill-food-supplement, some companies are blurring the line between safety and sales.

Luckily, the U.S. Food and Drug Administration (FDA) are on top of problem. The agency recently sent out warning notices to five companies that produce and distribute powdered caffeine products. The FDA expressed that their actions are meant to help prevent further deaths from powdered caffeine products, according to TIME.

Two young, relatively healthy, men died in 2014 after they both consumed powdered caffeine products. In the FDA warning letters sent to the companies, they said it was because “these products are dangerous and present a significant or unreasonable risk of illness or injury to consumers.”

The FDA has explained that there is a very small difference between a completely safe amount of pure powdered caffeine and an extremely dangerous amount. They said that it is almost impossible to measure safe amounts accurately with simple measuring tools. For instance, one teaspoon of pure powdered caffeine is the same as the amount of caffeine in 28 cups of coffee. Therefore, using a teaspoon to measure out a standard caffeine serving is not possible.

The companies that the FDA sent warnings to were SPN, LLC (Smartpowders), Purebulk, Inc., Kreativ Health Inc. (Natural Food Supplements), Hard Eight Nutrition, LLC and Bridge City Bulk.

The founder of Bridge City Bulk, Jeffrey Stratton, reported that the company “immediately stopped selling the material” as soon as they were notified of the warning, and since then, have not had any complaints.

The federal agency have said that they will continue to monitor the production, distribution and use of all powdered caffeine products. If, and when, any violations appear, they will immediately take action in order to stop the process and will seize the product or prevent producers from manufacturing it.