Federal officials have received reports of 13 deaths in the past four years that cited the possible involvement of 5-Hour Energy, a highly caffeinated energy shot, according to Food and Drug Administration (FDA) records and an interview with an agency official.

The disclosure of the reports is the second time in recent weeks that FDA 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 FDA, 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 FDA records reviewed by The New York Times showed.

The filing of an incident report with the FDA 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 that 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 FDA.

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 FDA to increase 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 2-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 8-ounce cup of coffee, depending on how it is made, can contain from 100 to 150 milligrams of caffeine.

The FDA has stated that it does not have sufficient scientific evidence to justify changing its regulation of caffeine or other ingredients in energy products. The issue is complicated because 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, 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.

Fabricant said that the 13 fatality reports that mentioned 5-Hour Energy had all been submitted to the FDA by Living Essentials. Since late 2008, producers of dietary supplements are required to notify the FDA when they become aware of deaths or serious injuries that may be related to their products.