A type of anxiety disorder in which a person has repeated panic attacks when there is no actual danger. Panic attacks are sudden periods of intense anxiety or fear that may cause irrational thoughts or actions. During a panic attack, a person may experience chest pain, trouble breathing, a fast heartbeat, sweating, shaking, dizziness, and feelings of impending doom or being out of control. Panic attacks may last for several minutes or longer. People with a panic disorder often worry that the panic attacks will happen again and try to avoid places or situations in which they have occurred.