The Federal Drug Administration says one 5-hour Energy drink has as much caffeine as two cups of coffee. Like most energy drinks, 5-hour Energy drinks are not required to list the amount of caffeine they contain. Now there's pressure to do that.
Golden Bear Market owner Sam Jaber says the demand for his famous Turkish coffee is rivaled by the demand for 5-hour Energy.
"I do sell a lot of it and I make sure I don't run out of it. I keep it in stock," said Jaber.
The FDA has received reports of 13 deaths over the last four years involving 5-hour Energy. Sandra Klingel, who is a nurse, says she had to take a man, who was working on her roof, to the hospital after he drank three of the drinks.
"His heart rate was beating so quickly that he was not getting enough blood to either his heart or his brain and so he became faint," said Klingel.
The San Francisco city attorney is demanding the makers of Monster Energy drinks -- another highly caffeinated drink -- prove the beverage is completely safe. The FDA says it may be linked to as many as five deaths since 2009.
Byron Lee, M.D., is a cardiologist at UCSF who suspects people are abusing the dosage. Lee said, "I think that if somebody were to have a pre-existing heart condition the increased adrenaline that may come with high doses of caffeine may tip them over the edge and eventually cause a lethal arrhythmia."
UCSF says it plans to release a report on the risks of energy drinks on Thursday. The makers of 5-hour Energy said it is "...unaware of any deaths proven to be caused by the consumption of 5-hour Energy." 5-hour Energy also recommends no more than two shots a day, spread out over several hours.
"I try to stay away from them, but they're cheap and they're easy to buy, so I go to them for my energy source," said Elizabeth Yurkov, a UCSF student.
Between 2005 and 2008 the Department of Health and Human Services reported a ten-fold increase in the number of emergency room visits linked to energy drinks.