A student in the UK who drank four 500ml energy drinks a day developed heart failure, a report by the British Medical Journal says.
The 21-year-old spent 58 days in hospital, including time in intensive care due to his two-year habit.
In the report the student called for energy drinks to be treated like cigarettes and have health warnings on them.
Before he was admitted to hospital, he suffered from shortness of breath and weight loss for four months.
He also developed severe biventricular heart failure and severe renal failure.
The student had no past medical history, was an ex-smoker and did not take illegal drugs.
"We report a case of severe biventricular heart failure potentially related to excessive energy drink consumption in a 21-year-old man," the report says.
"Energy drink consumption, specifically consuming an average of four 500 mL cans per day for approximately 2 years.
"Each can contains 160 mg of caffeine in addition to taurine and various other ingredients. Retrospectively, the patient recalls occasional symptoms of dyspepsia, tremor and a racing heartbeat but without seeking medical review. In the 3 months prior to admission he was unable to continue his university studies due to his lethargy and feelings of ill health."
The report says energy-drink induced cardiotoxicity was the most likely cause for the heart failure.
"This case report adds to the growing concern in the literature about the potential cardiotoxic effects of energy drinks," it writes.
The patient contributed to the report in order to raise awareness of the dangers of drinking too many energy drinks.
"I think there should be more awareness about energy drinks and the effect of their contents.
"I believe they are very addictive and far too accessible to young children. I think warning labels, similar to smoking, should be made to illustrate the potential dangers of the ingredients in energy drinks," he says in the report.
He described the 58 days in hospital as "extremely traumatising". He suffered from delirium and memory problems.
"I was constantly scared because I was struggling to move or speak, this eventually led to insomnia; I often would not fall asleep until early morning.
"Finally, I often became frustrated when I couldn't think of the words to say when I wanted something and this often led to me becoming overwhelmed with emotions such as anxiety and depression."