The Food and Drug Administration has received reports that the "5-Hour Energy" drink has been linked to 13 deaths in the United States.
The drink comes in two-ounce containers. It promises a sustained boost of energy, primarily from caffeine.
How much caffeine?
The bottle doesn't say. But the company now says it's 207 milligrams -- the same as 16 ounces of coffee, or nearly six cans of soda.
The company's founder, Manoj Bhargava, says there is no risk, to drinking his product. "None. Not at all. None," he told ABC News.
Of course, you can drink that two-ounce, room temperature, shot a lot faster than an entire cup of hot coffee.
And if you do drink too much five-hour energy, Bhargava says: "Don't get crazy. Don't take too much. That would really be a dumb thing to do. If you do dumb stuff, you're going to end up in the hospital."
The FDA now says it has received reports of 13 deaths and 33 hospitalizations over the past four years, claiming 5-Hour Energy was involved.
Those claims are being investigated.
At the same time, the FDA is looking into reports of five more deaths linked to Monster Energy drinks, including Anais Fournier of Hagerstown, who died in December of 2011.
She was just 14 years old, and she had a previous heart condition.
Her family blames her death on the two 24-ounce Monster Energy drinks she drank in less than 24 hours.
"Most people who manage patients with rhythm disorders try and advise patients to limit caffeine. Caffeine can definitely be a trigger," said Dr. Glenn Meninger of Union Memorial Hospital.
Fournier's family is suing the parent company of Monster Energy, which says it's done nothing wrong.
A spokesman for 5-Hour Energy says the claims of deaths related to that company's product have not been proven.