According to a recent case report released by eminent medical publication, The British Medical Journal, the answer is a very scary yes. The report charts the case of a previously healthy 50-year-old gent, who presented with a slew of symptoms such as nausea, vomiting, jaundice. The patient wasn't on any prescription or over-the-counter medication but was reported to be chugging four-to-five energy drinks daily for three weeks prior to his medical check-up. After running tests, they found he had a chronic hepatitis C infection, which they have since attributed to his excessive energy drink consumption. The good news is he's been treated and his symptoms have resolved but it does highlight just how much damage these energy drinks are capable of.
Some energy drinks have more than 20 teaspoons of sugar in one can - basically sugar-coma territory, not to mention the caffeine and other stimulants such as guarana - which like all stimulants can have side effects no one's interested in stocking up on (sleeplessness, heart palpitations, irritability etc). So next time you're looking for a caffeine boost, consider a cup of green tea instead.