
Unconsciousness is when a person is unable to respond to people and activities. Often, this is called a coma or being in a comatose state.
Other changes in awareness can occur without becoming unconscious. Medically, these are called "altered mental status" or "changed mental status." They include sudden confusion, disorientation, or stupor.
Unconsciousness and any other SUDDEN change in mental status must be treated as a medical emergency.
If someone is awake but less alert than usual, ask a few simple questions, such as:
Wrong answers or an inability to answer suggest a change in mental status.
Loss of consciousness - first aid; Coma - first aid; Mental status change; Altered mental status
Being asleep is not the same thing as being unconscious. A sleeping person will respond to loud noises or gentle shaking -- an unconscious person will not.
An unconscious person cannot cough or clear his or her throat. This can lead to death if the airway becomes blocked.
Unconsciousness can be caused by nearly any major illness or injury, as well as substance abuse and alcohol use.
Brief unconsciousness (or fainting) is often caused by dehydration, low blood sugar, or temporary low blood pressure. However, it can also be caused by serious heart or nervous system problems. Your doctor will determine if you need tests.
Other causes of fainting include straining during a bowel movement, coughing very hard, or breathing very fast (hyperventilating).
Call 911 if the person is unconscious and:
Marx JA, Hockberger RS, Walls RM, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 5th ed. St. Louis, Mo: Mosby; 2002.
Noble J, ed. Textbook of Primary Care Medicine. 3rd ed. St. Louis, Mo: Mosby; 2001.
Auerbach PS. Wilderness Medicine. 4th ed. St. Louis, Mo: Mosby; 2001.
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