Doctors have warned of the dangers of drinking too many energy drinks, after a middle-aged man who consumed five bottles a day developed acute hepatitis.
Experts issued the warning after their patient, a 50-year-old male, was admitted to hospital with severe liver damage.
The man, who has not been named by his doctors, said he had developed anorexia and worsening abdominal pain after he started drinking four to five cans of energy drinks every day to stay awake at work.
This progressed to nausea and vomiting.
He originally thought his symptoms were down to flu, but he became alarmed when he developed jaundice - a yellowing of the skin.
Doctors at University of Florida College of Medicine, writing in the journal BMJ Case Reports, found his symptoms were down to acute hepatitis - a severe disease of the liver.
Hepatatis is often linked to heavy alcohol or drug use but the patient did not drink, smoke or take illicit drugs.
His only unusual habit was his heavy consumption of energy drinks.
The doctors said the most likely cause of his hepatitis was overdose of vitamin B3, known as niacin, which is found in high concentrations in energy drinks.
They wrote: "Each bottle of his energy drink contained 40 mg of niacin, or 200 per cent of the recommended daily value and he consumed four to five bottles daily for more than 21 days straight."
The patient, who was discharged after six days, was told to stop consuming energy drinks.
His doctors wrote: "As the energy drink market continues to rapidly expand, consumers should be aware of the potential risks of their various ingredients.
"Vitamins and nutrients, such as niacin are present in quantities that greatly exceed the recommended daily intake, lending to their high risk for harmful accumulation and toxicity."
They added: "With the increasing popularity of energy drinks, clinicians should also be aware of the potential adverse effects associated with their consumption and inquire about energy drink intake in otherwise healthy adults who present with unexplained acute hepatitis.
"By alerting physicians to this phenomenon, we hope patients will be educated about the potential risks of energy drink overconsumption, and thus, many unnecessary liver injuries will be prevented, or at least promptly identified and treated appropriately."
Sales of energy drinks have soared over the last decade, jumping by more than 150 per cent in the UK since 2006.
The drinks are not recommended for children - but research suggests that they are incredibly popular among youngsters, who disregard the guidance.
A survey involving Britain and 15 other European countries found that 68 per cent of 11 to 18-year-olds and 18 per cent of children aged 10 and under consume energy drinks, with 11 per cent of the older group and 12 per cent of children drinking at least a litre in a single session.
Gavin Partington, director general of the British Soft Drinks Association, said: 'Niacin, also known as vitamin B3, is naturally found in many foods including meat, fish, eggs and milk.
"All the ingredients of energy drinks are safe and enjoyed by millions of people worldwide but like all food and drink should be consumed in moderation as part of a balanced, healthy diet."