The cardinal features of panic disorder are recurrent acute episodes of intense anxiety and fear and persistent worry about having another such episode. Symptoms include palpitations, sweating, shortness of breath, trembling or shaking, choking sensation, chest pain or discomfort, dizziness or light-headedness, paresthesias, chills or hot flashes, fear of losing control, fear of dying, derealization, and depersonalization. Episodes begin unexpectedly; severity peaks within 10 min and symptoms last for up to 1 hour.