Posttraumatic Stress Disorder is a disorder in which the patient develops severe symptoms of anxiety lasting a month or more after experiencing a traumatic event such as death, serious injury, of potential physical harm. The event may be directed at the patient or at others which the patient witnessed. In order to make the diagnosis, the patient experiences intense fear, horror, or helplessness. Anxiety symptoms may include repetitively re-experiencing the trauma, repetitively avoiding situations that are reminders of the trauma, and persistent symptoms of physiological arousal. At some point the patient realizes that the fear is excessive or irrational and the symptoms must significantly interfere with the patient’s daily routine, work or school performance, or social activities and relationships.

Acute Stress Disorder is similar to Posttraumatic Stress Disorder with the exception that the symptoms must occur within four weeks of the experience of the trauma and the symptoms persist for a minimum of two days and no longer than four weeks.