Caffeine is the most widely consumed psychoactive drug worldwide and appears to exert most of its biological effects through the antagonism of the adenosine receptor. Adenosine is an endogenous inhibitory neuromodulator that prompts feelings of drowsiness, and thus caffeine induces generally stimulatory effects in the central nervous system. In addition, the physiological effects of caffeine intake include acute elevation of blood pressure, increasing metabolic rate, and diuresis.3 Based on the data reviewed, it can be concluded that moderate caffeine intake (2–3 cups or 300mg/day) is not associated with adverse effects, such as cardiovascular stimulatory effects and behavioral changes, at least in healthy adults.4 However, caffeine is not completely harmless. In fact, caffeine crosses