In a new report, a large group of American doctors urge kids and teens to avoid energy drinks and only consume sports drinks in limited amount.
The recommendations come in the wake of a national debate over energy drinks, which experts fear may have side effects.
"Children never need energy drinks," said Dr. Holly Benjamin, of the American Academy of Pediatrics, who worked on the new report. "They contain caffeine and other stimulant substances that aren't nutritional, so you don't need them."
And kids might be more vulnerable to the contents of energy drinks than grownups.
"If you drink them on a regular basis, it stresses the body," Benjamin told Reuters Health. "You don't really want to stress the body of a person that's growing."
For the new recommendations, published in the journal Pediatrics, researchers went through earlier studies and reports on both energy drinks and sports drinks, which don't contain any stimulants.
They note that energy drinks contain a jumble of ingredients -- including vitamins and herbal extracts -- with possible side effects that aren't always well understood.
While there aren't many documented cases of harm directly linked to the beverages, stimulants can disturb the heart's rhythm and may lead to seizures in very rare cases, Benjamin said.
Recently, she saw a 15-year-old boy with attention deficit hyperactivity disorder who came into the hospital with a seizure after having drunk two 24-ounce bottles of Mountain Dew, a soft drink that contains caffeine.
The boy was already taking stimulant ADHD medication, and the extra caffeine in principle might have pushed him over the edge, according to Benjamin.
"You just never know," she said. "It's definitely a concern."
Earlier this year, Pediatrics published another review of the literature on energy drinks.
In it, Florida pediatricians described cases of seizures, delusions, heart problems and kidney or liver damage in people who had drunk one or more non-alcoholic energy drinks -- including brands like Red Bull, Spike Shooter and Redline.
While they acknowledged that such cases are very rare, and can't be conclusively linked to the drinks, they urged caution, especially in kids with medical conditions (see Reuters story of February 14, 2011).
U.S. sales of non-alcoholic energy drinks are expected to hit $9 billion this year, with children and young adults accounting for half the market.
Manufacturers claim their products will enhance both mental and physical performance, and were quick to downplay the February report.
"The effects of caffeine are well-known and as an 8.4 oz can of Red Bull contains about the same amount of caffeine as a cup of coffee (80 mg), it should be treated accordingly," Red Bull said in an emailed statement to Reuters Health.
Benjamin said that for most kids, water is the best thing to quench their thirst. If they happen to be young athletes training hard, a sports drink might be helpful, too, because it contains sugar.
But for kids who lead less-active lives, sports and energy drinks might just serve to pile on extra pounds, fueling the national obesity epidemic.
While she acknowledged that more research is needed, Benjamin said the safest thing to drink is water.