The US Food and Drug Administration is investigating 13 deaths that may be linked to consumption of an energy drink called 5-hour Energy, an FDA spokeswoman said Thursday.
"FDA is continuing to investigate reports of illness, injury or death of people who took products marketed under the label 5-Hour Energy," Shelly Burgess told AFP in an email.
There have been a total of 92 patient reports, including 33 hospitalizations and 13 deaths, she said.
She emphasised, however, that "the existence of an adverse event report does not necessarily mean that the product identified in the report actually caused the adverse event."
The FDA warns that energy drinks - rich in stimulants like caffeine - cannot substitute for rest or sleep and advises people to consult a doctor before consuming them, to ensure the product will not aggravate any undiagnosed medical problem.
This is the second investigation the FDA has launched in the last two months into potentially harmful effects from energy drinks.
In late October, the agency announced it was investigating five deaths and a non-fatal heart attack for possible links to consumption of Monster Energy drinks.
When energy drinks kill: Not the first case
Monster Beverage is also being sued in California by the family of Anais Fournier, a teenager who died of an arrhythmia in December 2011, allegedly after drinking two cans of Monster Energy over a 24 hour period.
Her parents accused the company of not warning consumers of the potential dangers of its product.
Two Democratic senators, Dick Durbin from Illinois and Richard Blumenthal from Connecticut, have demanded a meeting with FDA director Margaret Hamburg.
The meeting is "to discuss the steps the agency is taking to ensure the safety of these products," according to a release.
Living Essentials, the maker of 5-hour Energy, said it was taking the reports of deaths very seriously, while insisting it has not yet been proven any deaths were actually caused by consuming 5-Hour Energy.
Monster Beverage released a similar statement in October.
Other deaths from energy drinks:
Other deaths/hospitalisations due to energy drinks:
December 2011: Monster Energy
Anais Fournier, 14, drank two 24-ounce energy drinks on one December day while hanging out with her friends at the mall. The next day, she went into cardiac arrest and died just six days later.
Her parents are suing the California makers of Monster Energy, alleging that too much caffeine in the popular energy drink led to her death.
2007: Spike Shooter
Doherty High School in Colorado Springs banned a drink called Spike Shooter after two students were taken to hospital complaining of nausea, vomiting, fatigue, and heart palpitations.
They had been drinking Spike, which holds the dubious honor of being the most highly caffeinated 8oz drink. It contains 300 mg of caffeine per eight-ounce can.
Click through gallery to see what goes into a can of a 5-hour energy drink.