The surging consumption of highly caffeinated energy drinks has triggered concerns about health risks for children and teens, but it turns out that adult drinkers could be more likely to end up in hospital emergency rooms.

More than 5,000 patients age 40 and older visited ERs due to health problems related to energy drinks in 2011, according to a new federal report -- a number that has tripled since 2007. Twin Cities ER doctors said they were not surprised, because the young energy drinkers of the past are now older energy drinkers with chronic conditions and diseases that don't mesh well with caffeine overloads.

"Adults in some ways do better [than teens] because they're more tolerant to the drug," said Dr. Jon Cole, an ER physician and medical director of the Hennepin Regional Poison Center in Minneapolis.

"On the other hand, as they get older, they have more underlying cardiac and neurologic disorders that could be exacerbated by it."

Nationally, the number of energy-drink-related ER visits doubled in four years, from 10,068 in 2007 to 20,783 in 2011, according to a report released Wednesday by the U.S. Substance Abuse and Mental Health Services Administration. Patients sought treatment for irregular or racing heartbeats, anxiety, seizures and other problems, and, overall, visits were most common among men aged 19 to 25.

The numbers in Wednesday's report tracked the rapid growth of energy drinks in recent years. Sales of Red Bull, for example, soared to 4.6 billion cans worldwide in 2011, with consumption rising 11 percent in the United States, 35 percent in France and 62 percent in Japan.

Rare but high-profile tragedies -- such as the death of a 14-year-old girl in Maryland who drank two large cans of an energy drink -- have drawn attention to the safety risks and brought calls from lawmakers to investigate the beverages and the accuracy of their ingredient lists.

The American Beverage Association, which represents energy-drink makers, said the federal report only counts patients in the ER who consumed energy drinks, and doesn't prove that energy drinks caused all of their symptoms, especially given the number of patients who took other substances. The organization says the products are safe and that many contain the same amount of caffeine as coffeehouse coffee.

'Sense of doom'

The increasing popularity of energy drinks -- which now fill entire banks of convenience stores with cans bearing the names Monster, Rock Star and Full Throttle -- prompted the Hennepin Regional Poison Center to track calls about people suffering health problems related to their consumption. The center reported 73 Minnesota cases since 2011, but no deaths.

Around the Twin Cities, adult drinkers expressed little surprise at the ER numbers, but suspected that they didn't involve regular consumers and instead involved novices who binged on them or took them with other substances. The federal report noted that 42 percent of the ER patients also had consumed alcohol or other drugs.

Brad Benson, 37, of Minnetonka said he has had "funny feelings" from too much caffeine, but not severe health problems from the combination of coffee, Mountain Dew and energy drinks that he consumes daily to work a late shift at night and help with his five kids during the day. "I'm so used to the amount of caffeine," he said, "that I don't really notice it anymore."

James Cave, 44, takes one low-carb Monster out of the fridge every day and cracks it open and sips it all morning in his history classroom at the Hmong College Prep Academy in St. Paul. Cave, who is raising six children, none of whom consume energy drinks, said his students notice if he tries a new flavor.

The Poison Center's Cole said energy drinks are a growing problem among adults and teens, but hardly at the level of prescription drugs and alcohol in terms of abuse and misuse.

Twin Cities ER doctors said patients who have overloaded on energy drinks show similar symptoms, and that asking about energy drinks has become almost automatic when teens report erratic or racing heartbeats.

"Someone will come up to the triage desk and say, 'I'm having palpitations or chest pains or shortness of breath or anxiety,''' said Dr. Jay Westwater, an ER physician at United Hospital in St. Paul. Cole said that in rare cases, patients report "this impending sense of doom. They feel like something terrible is going to happen to them and they have a hard time articulating it beyond that."

Brandy Boyer, 35, of Hastings said the worst health problems he ever experienced were the crushing headaches when he tried to quit energy drinks and all other forms of caffeine. He started taking them for an energy boost when he played semi-pro football a decade ago, and over time found them cheaper and tastier than gourmet coffee.

Boyer isn't sure if he drinks them for a caffeine surge anymore, or just for the habit. "I can't go a day without one," he said, "minimum."

Jeremy Olson • 612-673-7744