BOSTON -- Poison control centers and emergency rooms in the Boston area and nationwide have noted a spike in calls about caffeine poisoning, Boston television station WCVB reported.

A recently released report by University of Massachusetts Medical School toxicologist Richard Church tracked 4,600 caffeine-related calls to poison control nationwide in 2005, the most recent statistics available. Half involved people under age 19.

It’s all too familiar to the poison control center at Children’s Hospital Boston, where directors confirm receiving dozens of similar calls. Alfred Aleguas, the clinical manager of the regional poison control, located at Children's Hospital Boston, said, “The majority of calls come from school nurses and parents.”

Experts point to energy drinks, the aggressively marketed, caffeine-packed beverages that are sold in nearly every convenience and grocery store as part of the cause of the disturbing trend.

With names like Red Bull, Burn, Rock Star, Adrenaline Rush and even Free Cocaine, the drinks are growing in popularity, becoming the fuel of choice for some teens.

"They do give me an energy burst," said one teenager WCVB-TV interviewed. Another said, "If you’re feeling a little sluggish, it gives you energy."

But others admitted, "It makes my heart beat too fast," and one young girl told WCVB, "I got sick from it once."

"The effects of caffeine are potentially very, very serious," said Dr. Richard Church, a toxicologist at UMass Medical School whose eye-opening report calculated caffeine-related calls to poison control. "We were noticing an influx of patients in our ER who were coming in with caffeine-related complaints and symptoms after drinking energy drinks," Church said.

Some drinks are loaded with two to three times the amount of caffeine that's in a regular cup of coffee. Red Bull has 80 milligrams of caffeine per 8.3 ounce can. Monster has 160mg. Rock Star contains 160mg, and Free Cocaine contains 280mg. Some cans contain more than one serving.

Church said when teenagers don’t realize how much caffeine they are ingesting, "that's when we start see kids coming in with intractable vomiting where they can't stop vomiting. They're having severe headaches and they're feeling like their heart is racing."

But energy drinks may be only part of the story. WCVB discovered extra caffeine is being added to gum, mints, candy bars, even lip balm. A small bag of one caffeine-infused snack food called Engobi contains as much caffeine as two Red Bull drinks, but consumers would never know that by reading the label. Companies often don't specify how much caffeine individual products contain. And other ingredients may add an extra punch.

"Yerba mate, colo nut, cocoa. These are all things that have caffeine in them," said Church.

WCVB discovered these ingredients are not regulated by the Food and Drug Administration.

"The amount of caffeine that's in them is not controlled or looked at at all," said longtime pediatrician John Cohen.

Cohen cautions parents and teenagers to know what they are putting in their bodies, because too much caffeine, he said, could get them into serious medical trouble.

"In my opinion," Cohen said, "All this stuff should be pulled off the market."

Everyone is susceptible to the effects of too much caffeine, doctors WCVB interviewed said people with pre-existing heart or seizure conditions are most at risk of caffeine poisoning.

WCVB contacted the American Beverage Association for its reaction to the UMass Medical School report. The ABA said, "Caffeinated beverages, including energy drinks, can be part of a balanced lifestyle when consumed sensibly."

The statement went on to say that energy drinks "have not been uniquely associated with negative health effects. Importantly, the amount of caffeine contained in mainstream energy drinks is modest, particularly when compared to coffee."