Acute stress disorder is a brief period of intrusive recollections occurring shortly after an overwhelming traumatic event. It is similar to posttraumatic stress disorder, except that it begins within 4 weeks of the traumatic event and lasts only 2 days to 4 weeks.
People with acute stress disorder have been exposed to a terrifying event. They mentally reexperience the traumatic event, avoid things that remind them of it, and have increased anxiety. They also have three or more of the following symptoms:
• A sense of numbing, detachment, or lack of emotional responsiveness
• Reduced awareness of surroundings (for example, being dazed)
• A feeling that things are not real
• A feeling that they are not real
• An inability to remember an important part of the traumatic event.
The number of people with acute stress disorder is unknown. The likelihood of developing acute stress disorder is greater when traumatic events are severe.
Treatment
Many people recover from acute stress disorder once they are removed from the traumatic situation and given appropriate support in the form of understanding, empathy for their distress, and an opportunity to describe what happened and their reaction to it. Some people benefit from describing their experience several times.
Resource: Merck Manual Home Edition