“ Any unexplained phenomenon passes through three stages before the reality of it is accepted. During the first stage it is considered laughable. During the second stage, it is adamantly opposed. Finally, during the third stage, it is accepted as self-evident. ” - Arthur Schopenhauer

Other anxiety disorders include Anxiety Disorders due to a General Medical Condition (where the anxiety is a direct physiological consequence of a general medical condition), Substance-Induced Anxiety Disorder (where the anxiety is directly caused by the physiological effects of a substance - drug of abuse or medication - including prescription use, poisoning, intoxication, or withdrawal), and Anxiety Disorder Not Otherwise Specified (where there is prominent clinically significant anxiety or phobic avoidance that doesn't meet the diagnostic criteria for any other anxiety or adjustment disorder).

Health anxiety disorder and hypochondriasis are typically classified under Somatoform disorders.