By law, all energy drinks are clearly labelled with total caffeine amounts and maximum usage recommendations. (australianbeverages.org)
Generally, a dose between 250 - 500 mg (check caffeine amounts here) could produce some of the above mild to moderate symptoms, especially in those with no tolerance of high caffeine sensitivity. (caffeineinformer.com)
The reason for this is because of its high caffeine amount and astringent flavorings. (bigrockcoffee.com)