Northumbria University gave sports science students Alex Rossetto and Luke Parkin the equivalent of 300 cups of coffee, which was 100 times more than the study called for, Metro reported.
The two men were admitted to an intensive care unit for dialysis after the error led to violent side-effects, according to BBC.
The university said it was “deeply, genuinely sorry" and was fined about $500,000 for its mistake, BBC reported.
Rossetto and Parkin agreed to participate in the study, which was looking to measure the effects of caffeine on exercise. Both men made full recoveries, but Rossetto did suffer from short-term memory loss, the BBC reported.