Anxiolytics (synonym, tranquillizers) are antianxiety drugs that are used in the pharmacological treatment of anxiety disorders. Anxiety is rather untypical for psychiatric disorders in that it may occur as both a normal emotional and a pathological state. During early human history, anxiety was probably adaptive and thus a criterion for selection. This may explain the high lifetime prevalence for anxiety states (≥15 % of population; Nutt 2003). Anxiety disorders often first emerge during childhood and adolescence and represent one of the most common forms of psychopathology among children and adolescents. Anxiety disorders include seven major debilitating subtype disorders: separation anxiety disorder, generalized anxiety disorder, social phobia, panic disorder (with and without agoraphobia), agoraphobia without panic disorder, post-traumatic stress disorder, and obsessive-compulsive disorder (OCD).