Rating Newest Oldest. Best Answer: The Monster energy drinks not only contain a lot of caffeine, they also contain a large amount of carbohydrates and sugar. The sugar content of Monster energy drink poses certain side effects.It causes so-called laxative effect as well as sudden crash in energy level when sugar leaves the bloodstream. Although it is not necessarily a dangerous effect, but it can create other adverse effects.he sugar content of Monster energy drink poses certain side effects. It causes so-called laxative effect as well as sudden crash in energy level when sugar leaves the bloodstream. Although it is not necessarily a dangerous effect, but it can create other adverse effects.