Five deaths and a non-fatal heart attack have been linked in US reports to highly-caffeinated Monster Energy Drinks.

The The US Food and Drug Administration acknowledged the adverse reports, but FDA spokeswoman Shelly Burgess said they did not prove that the drinks caused the deaths.

The news follows last week's filing in California of a wrongful death suit by the parents of a 14-year-old girl from Hagerstown, Maryland, who died after drinking two, 24oz Monster Beverage Corporation drinks in 24 hours.

A post-mortem examination concluded she died of cardiac arrhythmia due to caffeine toxicity. She had an inherited disorder that can weaken blood vessels.

Monster says it does not believe its products caused any deaths.

Shares of the Corona, California-based company plunged 7.20 dollars, or 13.5%, to 46.12 dollars in trading today.

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