ATLANTA (AP) — First, a prom king and athlete who took powdered caffeine died in May, days before he was supposed to graduate from high school in Ohio.

The next month, a Georgia man slipped into a coma and later died after taking the same substance.

The pure caffeine is easily available online, but this week a U.S. Food and Drug Administration official stressed that people should avoid using it while the agency decides whether to take steps to curb its use.

Michael Landa, director of the FDA’s Center for Food Safety and Applied Nutrition, wrote about the two men on the FDA’s website this week after meeting their parents in Washington, D.C.

Logan James Stiner, 18, died May 27 after taking the substance, Landa said. His parents traveled to Washington from LaGrange, Ohio, this month to urge regulators to ban sales of the substance.

James Wade Sweatt, 24, a recent University of Alabama-Birmingham graduate from Alpharetta, Georgia, died June 24. His death came after he was in a coma caused by using pure powdered caffeine, Landa wrote.

On Dec. 9, parents of the two men met with lawmakers and federal regulators and told them that more needs to be done to protect children from the powdered form of caffeine. Available online, it’s marketed as an energy booster, Landa noted.

“The powdered pure caffeine that the Stiners and Sweatts brought to show us — readily available for purchase online — was packaged in the same way as protein powder and marketed as a source of energy, rather than a stimulant,” Landa wrote.

“The reality is that these products are 100 percent caffeine, with a single teaspoon roughly the equivalent to the amount in 25 cups of coffee,” he added. “Pure caffeine is a powerful stimulant and even very small amounts may cause an accidental overdose.”

Because caffeine powder is sold as a dietary supplement, it’s not subject to the same federal regulations as certain caffeinated foods. Users add it to drinks for a pick-me-up before workouts or to control weight gain, but it is almost impossible to measure with common kitchen tools, according to the FDA.

In a statement Dec. 9, the FDA said that it was continuing its investigation and that since it sent a warning to consumers in July, some online retailers have discontinued sales. The agency didn’t indicate how long its review may take or what regulatory action it was considering.

“We are working right now on our next steps,” Landa wrote this week. “In the meantime, I cannot say strongly enough how important it is to avoid using powdered pure caffeine. The people most drawn to it are our children, teenagers, and young adults, especially students who want to work longer to study, athletes who want to improve their performance, and others who want to lose weight.”