The U.S. Food and Drug administration has confirmed that the popular caffeine drink, 5-hour Energy, may have played a role in 13 deaths over the past four years.

FDA spokeswoman Shelly Burgess told the New York Times 5-hour Energy, sold by Living Essentials, has been mentioned in some 90 FDA filings since 2009, including more than 30 that involved serious or life-threatening events like heart attacks, convulsions, and in one case, a spontaneous abortion.

According to the newspaper, the Substance Abuse and Mental Health Services Administration reported late last year that more than 13,000 emergency room visits in 2009 were associated with energy drinks alone.

A recent report by Beverage Digest, cited by Reuters, suggests that the highly caffeinated beverages are the fastest-growing type of soft drink in the United States, with sales increasing 17 percent last year to about $9 billion.

Elaine Lutz, spokeswoman for Living Essentials, the company that distributes 5-hour Energy, said in a statement, obtained by Reuters, that the product "is not an energy drink" (the so-called shot comes in a bottle that holds less than 2 ounces).

"Living Essentials," the statement went on, "takes reports of any potential adverse event tied to our products very seriously. We fully comply with all of our reporting requirements." The company was "unaware of any deaths proven to have been caused by the consumption of 5-hour Energy."

5-Hour Energy said on its website that its energy shot contains the same amount of caffeine as 12 ounces of the leading cup of premium coffee.