Panic disorder is characterized by seemingly un-triggered unexpected anxiety. The client experiences a sudden upsurge of sensations, such as palpitations, sweating, trembling, shaking, shortness of breath, chest pain, nausea, dizziness, chills, and numbness. They may fear that they are in imminent danger of going crazy, losing touch with reality, fainting, losing control of their bowels, having a heart attack or stroke, or dying. If combined with agoraphobia, they may avoid crowds, travel, driving, exercise, standing in line, or any situation where they perceive that escape might be difficult. Panic attacks are uncomfortable, but not dangerous. To earn a diagnosis of panic disorder, clients spend at least one month worrying about having more panic attacks, worrying about the consequences of panic attacks and avoiding activities that they value or once enjoyed.