Federal officials have received reports of 13 deaths over the last four years that cited the possible involvement of 5-Hour Energy, a highly caffeinated energy shot, according to Food and Drug Administration records and an interview with an agency official.
The disclosure of the reports is the second time in recent weeks that F.D.A. filings citing energy drinks and deaths have emerged. Last month, the agency acknowledged it had received five fatality filings mentioning another popular energy drink, Monster Energy.
Since 2009, 5-Hour Energy has been mentioned in some 90 filings with the F.D.A., including more than 30 that involved serious or life-threatening injuries like heart attacks, convulsions and, in one case, a spontaneous abortion, a summary of F.D.A. records reviewed by The New York Times showed.
The filing of an incident report with the F.D.A. does not mean that a product was responsible for a death or an injury or contributed in any way to it. Such reports can be fragmentary in nature and difficult to investigate.
The distributor of 5-Hour Energy, Living Essentials of Farmington Hills, Mich., did not respond to written questions about the filings, and its top executive declined to be interviewed. Living Essentials is a unit of the product's producer, Innovation Ventures.
However, in a statement, Living Essentials said the product was safe when used as directed and that it was "unaware of any deaths proven to be caused by the consumption of 5-Hour Energy."
Since the public disclosure of reports about Monster Energy, its producer, Monster Beverage of Corona, Calif., has repeatedly said that its products are safe, adding that they were not the cause of any of the health problems reported to the F.D.A.
Shares of Monster Beverage, which traded above $80 earlier this year, closed Wednesday at $44.74.
The fast-growing energy drink industry is facing increasing scrutiny over issues like labeling disclosures and possible health risks. Some lawmakers are calling on the F.D.A. to increase its regulation of the products and the New York State attorney general is investigating the practices of several producers.
Unlike Red Bull, Monster Energy and some other energy drinks that look like beverages, 5-Hour Energy is sold in a two-ounce bottle referred to as a shot. The company does not disclose the amount of caffeine in each bottle, but a recent article published by Consumer Reports placed that level at about 215 milligrams.
An eight-ounce cup of coffee, depending on how it is made, can contain from 100 to 150 milligrams of caffeine.
The F.D.A. has stated that it does not have sufficient scientific evidence to justify changing how it regulates caffeine or other ingredients in energy products. The issue of how to do so is complicated by the fact that some high-caffeine drinks, like Red Bull, are sold under agency rules governing beverages, while others, like 5-Hour Energy and Monster Energy, are marketed as dietary supplements. The categories have differing ingredient rules and reporting requirements.
In an interview Wednesday, Daniel Fabricant, the director of the agency's division of dietary supplement programs, said the agency was looking into the death reports that cited 5-Hour Energy. He said that while medical information in such reports could rule out a link with the product, other reports could contain insufficient information to determine what role, if any, a supplement might have played.
Mr. Fabricant said that the 13 fatality reports that mentioned 5-Hour Energy had all been submitted to the F.D.A. by Living Essentials. Since late 2008, producers of dietary supplements are required to notify the F.D.A. when they become aware of a death or serious injury that may be related to their product.
Currently, the agency does not publicly disclose adverse event filings about dietary supplements like 5-Hour Energy. Companies that market energy drinks as beverages are not required to make such reports to the agency, although they can do so voluntarily, Mr. Fabricant said.
Along with caffeine, 5-Hour Energy contains other ingredients, like very high levels of certain B vitamins and an amino acid called taurine.
Reached by telephone, the chief executive of the Living Essentials, Manoj Bhargava, declined to discuss the filings and said he believed an article about the reports would cast the company in a negative light.
"I am not interested in making any comment," Mr. Bhargava said.
Subsequently, the company issued a statement, that said, among other things, that it took "reports of any potential adverse event tied to our products very seriously," adding that the company complied "with all of our reporting requirements" to the F.D.A.
The company also stated that it marketed 5-Hour Energy to "hardworking adults who need an extra boost of energy." The product's label recommends that it not be used by woman who are pregnant or by children under 12 years of age.
The number of reports filed with the F.D.A. that mention 5-Hour Energy appears particularly striking. In 2010, for example, the F.D.A. received a total of 17 fatality reports that mentioned a dietary supplement or a weight loss product, two broad categories that cover more than 50,000 products, according to Mr. Fabricant, the F.D.A. official.
He added that it was difficult to put the volume of 5-Hour Energy filings into context because he believed that some supplement manufacturers were probably not following the mandated reporting rules and that consumers and doctors might also be unaware that they can file incident reports with the agency. Last year, the F.D.A. received only 2,000 reports about fatalities or serious injuries that cited dietary supplements and weight loss products, he said.
Another federal agency, 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.
Along with Living Essentials, The Times sent queries last week to several producers asking whether they had received reports linking fatalities or serious injuries to their products.
Representatives for two of those companies — Red Bull and Coca-Cola, which sells NOS and Full Throttle — said they were unaware of any such reports. A representative for PepsiCo, which makes Amp, declined to comment, stating that such reports constituted "nonpublic information."
In addition to Red Bull, NOS, Full Throttle and Amp are also marketed as beverages, rather than as dietary supplements.