A teenager was taken to hospital in Darlington after drinking eight cans of energy drink Red Bull.
Each 250ml can of Red Bull contains about 80mg of caffeine
The 15-year-old, a pupil at Hummersknott Comprehensive School, suffered heart palpitations, according to paramedics.
He was treated at the Memorial Hospital following the 14 February incident, details of which have just emerged.
A Red Bull spokesman recommended only one to two cans of the energy drink for "optimum effect".
Each 250ml can of Red Bull contains 80mg of caffeine - the equivalent, says the company, to a weak cup of filter coffee.
The spokesman added: "Red Bull energy drink is a functional product which has been developed specifically for periods of mental or physical exertion.
"We have always recommended drinking one to two cans of Red Bull to have the optimum effect on performance in times of need."
Red Bull has come under fire in the past for being linked with health problems.
Norway, France, Uruguay and Iceland have all banned the energy drink because of concerns over high levels of caffeine.