Commonly reported adverse effects due to caffeine used in the quantities present in Red Bull are insomnia , nervousness , headache , and tachycardia ( see Caffeine intoxication ) . Commonly reported adverse effects due to consumption of the levels of caffeine used in the quantities commonly present in Red Bull are effects such as headache , nausea , and anxiety ( see Health effects of caffeine ) . For drinking too much Red Bull and side-effects including tachycardia ( see Caffeine intoxication ) .