A 22-year old woman went to the hospital complaining of upper abdominal pain, fever, nausea and vomiting according to the June 22nd edition of the  Journal of Medical Case Reports. She was sent home but returned even sicker the next day, but this time with a yellowish tint. The doctors discovered the young woman's liver was failing due to the fact she was drinking 10 bottles a day of 5-Hour energy. She was diagnosed with acute hepatitis. Doctors believe that the overdose on niacin, also called Vitamin B3, was the reason her liver was damaged.

Moral of the story, read the instructions. The back of the bottle says "do not exceed more than two bottles per day."