Dexmedetomidine (Dex) is a highly selective α2-adrenergic receptor agonist, and characterized in sedation, anti-anxiety, sympathetic nerve blockage, decreased anesthetic doses and little effect on respiration. To review and summarize related studies, we evaluate the effects of Dex on renal and hepatic damages, children, elderly people and off-label uses. Dex is safe and effective in specific populations, and its off-label use requires further studies.