Supermarket shelf stacker Alfredo Duran, 40, collapsed with a heart attack at the end of a night shift.
Coroner Nicholas Gardiner said he could not say the caffeine level was high enough to have caused a heart attack.
He added: "I do not think we can go on a witch hunt for Red Bull on the strength of this."
'Strong coffee'
Recording his verdict, Oxfordshire coroner Mr Gardiner said: "I think it was almost certainly the case that Alfredo Duran had an underlying heart condition.
"And, there are papers that show that caffeine can cause heart arrhythmia, but we were not able to say in this case that the caffeine was definitely high enough to have caused his heart attack.
"A can of Red Bull contains about as much caffeine as a strong cup of coffee."
A Red Bull spokesman stated "numerous" tests by independent experts had concluded it was as safe as any other drink for adults.
He said: "No-one has ever shown any link between Red Bull energy drink and harmful effects.
"We make a recommendation that people should drink one to two cans a day, as they would with cups of coffee."
(BBC.com)