TUESDAY, Nov. 22 (HealthDay News) -- As the popularity of non-alcoholic "energy" drinks skyrockets, so do related health problems, a new study finds.

In 2009, U.S. emergency rooms treated almost 10 times more cases of reactions to beverages such as Monster and Rockstar than they did in 2005, according to a new U.S. government report released Tuesday.

More than 13,000 ER visits related to the highly caffeinated drinks were reported in 2009, said researchers from the U.S. Substance Abuse and Mental Health Services Administration (SAMHSA). Nearly half the emergencies occurred after the beverages were mixed with alcohol or other drugs, and young adults aged 18 to 25 accounted for more than half of those cases, the researchers found.

"A lot of attention has been paid to energy drinks that have alcohol in them and everybody understands that the effect of that can be pretty serious, but energy drinks by themselves can have adverse effects," said lead author Albert Woodward, project director of SAMHSA's Drug Abuse Warning Network.

Sales of these flavored drinks soared 240 percent from 2004 to 2009, Woodward said. Popular brands include Red Bull, Full Throttle (produced by Coca-Cola) and AMP, in addition to Monster and Rockstar.

The drinks contain stimulants such as caffeine, and the amount of caffeine in a can or bottle varies by brand. Whereas a five-ounce cup of coffee contains about 100 milligrams (mg) of caffeine and a 12-ounce cola about 50 mg, some energy drinks contain about 80 mg, others as much as 500 mg, according to the report.

"That's a huge dose of caffeine," said Dr. Jeffrey N. Bernstein, medical director of the Florida Poison Information Center at the University of Miami Miller School of Medicine.

High doses of caffeine can cause abnormal heart rhythms, high blood pressure, dehydration and other serious conditions.

"Many of the patients who come in have anxiety and their heart is pounding and they are just feeling sick," Bernstein said.

The drinks, sold in cans and bottles in grocery stores, vending machines, bars and other places, are marketed to young people. Up to 50 percent of children, teens and young adults use them, the researchers said in the report.

For the study, the investigators reviewed data from the Drug Abuse Warning Network, which monitors drug-related hospital emergency department visits reported throughout the United States. In 2005, more than 1,100 people sought emergency treatment for adverse reactions to energy drinks. By 2009, ERs treated over 13,000 energy drink patients. More than 16,000 such visits occurred in 2008, the most ever, the researchers found.

Alcohol, pharmaceuticals or illicit drugs were associated with 44 percent of the emergencies, and 52 percent of those visits involved patients 18 to 25 years old.

Overall, young adults between 18 and 39 years old made up more than three-quarters of all the ER visits, and 64 percent were men, the data showed.

Men were twice as likely as women to use alcohol and drugs along with an energy drink. But, more women than men combined energy drinks with pharmaceuticals, the researchers reported.

People who combine these energy drinks with substances of abuse have a raised risk of serious and potentially life-threatening injury, the study authors noted in a SAMHSA news release. In addition, there is a greater likelihood that they will engage in risky behaviors, including driving under the influence.

A group representing beverage makers took issue with the report, however.

"This paper is a troubling example of statistics taken out of context," said a statement released Tuesday by the American Beverage Association (ABA). "Of the more than 123 million visits made to emergency room facilities each year, less than one-hundredth of one percent involved people who consumed energy drinks according to this report."

The ABA goes on to note that, "energy drinks and their ingredients are safe and approved by the U.S. Food and Drug Administration," adding that the report "does not show that energy drinks cause misuse of alcohol."

Nevertheless, some people are especially susceptible to caffeine, Bernstein believes. "If you are susceptible to high blood pressure, it can also be a risk," he said. "If you overdo it, a night in the ER is no day at the beach," he noted.

More information

For more information on caffeine, visit the U.S. National Library of Medicine.