Among the pros of energy drinks are increased alertness and productivity, while the cons include weight gain and cardiovascular issues. The consumption of energy drinks can also lead to unpleasant side effects such as anxiety, jitters and irritability.
Energy drinks from brands such as Red Bull and Monster tend to have very high levels of caffeine or equivalent stimulants like guarana and ginseng. For some, this may lead to heart palpitations and high blood pressure, along with dehydration and insomnia. In light of their dehydrating effect, and contrary to common assumptions, energy drinks should not be combined with heavy physical labor or exercise, since such a combination risks severe dehydration.
Energy drinks are more convenient than coffee or tea, in that they provide an instant boost in a can. However, their marketing or packaging can be misleading. For instance, the can might display the caffeine content of one serving without making it immediately obvious that one "serving" equates to only half the can's contents. It therefore becomes more difficult to accurately moderate one's intake of stimulants.
It is common to use energy drinks as a mixer with alcohol, but this can lead to problems. Aside from the doubled dehydration, which further impairs the body's metabolizing of alcohol and leads to greater toxicity and hangover, the stimulant effect of energy drinks disguises the depressant effect of alcohol. As a result, people tend to drink more, having missed or overridden natural cues, like fatigue, to stop drinking.