CBS News medical contributor Dr. David Agus agrees. He told the co-hosts of "CBS This Morning" Thursday that these drinks pack quite a punch -- too much stimulation for many kids to handle.
"For the past couple of years, thousands of children are being admitted to emergency rooms with cardiac problems and other issues from drinking energy drinks," Agus said, "and it's going up at an alarming pace."
The San Francisco city attorney and the New York state attorney launched the joint probe last month.
In a statement to CBS News, the Monster company said: "Our products are safe. They are not highly caffeinated, and they are not marketed to children."
Agus said that response is misleading. "The cans have caffeine in them, ginseng, and guarano, all of which have the same caffeine-like properties, and they're big stimulants. They affect the heart and the brain," Agus said. And they are full of sugar, he added, which make them appealing to kids and teens.
"When you drink a cup of coffee, you drink it over 30, 40 minutes. These cans you gulp," Agus said. "All those caffeine-like properties, it's the perfect storm. You get electrical, conductive changes in the heart. That's why kids are ending up in the emergency room."
Agus said these drinks are also damaging to adults, but it is the younger generation that is more drawn to them. "Kids do it to get through finals, or on weekends to stay up late at night -- adults, not that much."
He said it would be wise to look at regulating energy drinks, much like the FDA regulates other stimulants.
"No question about it," Agus said. "We regulate Ritalin. We regulate Adderall. We should be regulating these cans. And we should be quantifying how much stimulant is in them."