How much caffeine is really in those energy drinks?

By Deborah Kotz, Globe Staff

Monster energy drink can REUTERS/Sam Mircovich

How much caffeine is in those energy drinks that teens love to consume? Consumer Reports posted results of its lab testing today to give consumers a clear idea of how much they’re consuming in every serving. Of the 27 products tested, 11 didn’t specify the amount of caffeine on the label since they aren’t obligated to legally; five of the 16 that did list the amount had more than 20 percent more than was stated on the label.

Energy drinks have been under attack this week with a lawsuit waged by Maryland parents after their 14-year-old daughter, Anais Fournier, went into cardiac arrest and died after drinking two, 24-ounce Monster Energy drinks in a day. The drink label says it’s not intended for use in those under 18, and previous research suggests that kids are particularly susceptible to caffeine overdoses triggered by an overconsumption of these beverages.

The US Food and Drug Administration also announced that they were investigating the caffeine content in energy drinks after receiving reports of five deaths and one heart attack also linked to the consumption of Monster Energy.

Monster Energy said in a statement that it “has sold more than 8 billion energy drinks...and does not believe that its beverages are in any way responsible for the death of Ms. Fournier. Monster is unaware of any fatality anywhere that has been caused by its drinks.”

Consumer Reports found that Monster Energy contained 92 milligrams of caffeine per 8-ounce serving; that compares to 100 mg in an 8-ounce cup of coffee. Starbucks Short (8-ounce) espresso drinks -- latte, cappuchino, macchiato -- have 75 to 90 mg of caffeine. Its brewed coffee has 150 to 175 mg for a Short serving.

But serving sizes can be misleading since many folks consume whatever’s in the container. The most popular Starbucks size is Grande (16-ounces), which has twice as much caffeine. Monster Energy cans come in 24-ounces, which is 276 mg.

While a little caffeine can increase alertness, boost mood, and give you more energy, too much can cause heart palpitations, nausea, dizziness, high blood pressure, and insomnia.

Consumer Reports found seven brands of energy drinks that contain more than 200 mg of caffeine per serving, which are listed below.

Full Throttle (210 mg)

Celsius (212 mg)

5-Hour Energy (215 mg)

Monster X-presso (221 mg)

NOS High Performance Energy Drink (224 mg)

Rockstar Energy Shot (229 mg)

5-Hour Energy Extra Strength (242 mg)

Deborah Kotz can be reached at dkotz@globe.com. Follow her on Twitter @debkotz2.