Denver ? A high school banned a caffeine-packed energy drink and 7-Eleven pulled it from Colorado stores after some students said it made them sick and shaky and caused their hearts to race.

About a half-dozen students became sick in the last two weeks and two were hospitalized after drinking Spike Shooter, made by Biotest Laboratories LLC. All recovered within hours, said Dennis Vigil, assistant principal at Doherty High School in Colorado Springs.

A warning on the can says the drink isn’t meant for anyone under 18, said Biotest spokesman Tom DeNardin. The drink contains roughly the same amount of caffeine as two to three five-ounce cups of coffee.

7-Eleven Inc. pulled the drink from all 222 of its company-owned stores in Colorado after the school asked nearby stores to limit sales to students, spokeswoman Margaret Chabris said. The corporation had never recommended Spike Shooter to its stores and it was not distributed by the company’s approved suppliers, she said.