Loss of consciousness - first aid; Coma - first aid; Mental status change; Altered mental status; Syncope - first aid; Faint - first aid
Unconsciousness can be caused by nearly any major illness or injury. It can also be caused by substance (drug) and alcohol use. Choking on an object can result in unconsciousness as well.
Brief unconsciousness (or fainting) is often a result from dehydration, low blood sugar, or temporary low blood pressure. It can also be caused by serious heart or nervous system problems. A doctor will determine if the affected person needs tests.
Other causes of fainting include straining during a bowel movement (vasovagal syncope), coughing very hard, or breathing very fast (hyperventilating).
Unconsciousness is when a person is unable to respond to people and activities. Doctors often call this a coma or being in a comatose state.
Other changes in awareness can occur without becoming unconscious. These are called altered mental status or changed mental status. They include sudden confusion, disorientation, or stupor.
Unconsciousness or 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 not being able to answer the question suggest a change in mental status.
If a person is unconscious or has a change in mental status, follow these first aid steps:
If the person is unconscious from choking:
To prevent becoming unconscious or fainting:
If you have a medical condition, such as diabetes, always wear a medical alert necklace or bracelet.
The person will be unresponsive (does not respond to activity, touch, sound, or other stimulation).
The following symptoms may occur after a person has been unconscious:
If the person is unconscious from choking, symptoms may include:
Being asleep is not the same as being unconscious. A sleeping person will respond to loud noises or gentle shaking. An unconscious person will not.
Call 911 if the person is unconscious and:
Call 911 if the person regains consciousness, but:
American Red Cross. First Aid/CPR/AED Participant's Manual. 2nd ed. Dallas, TX: American Red Cross; 2016.
Bassin BS, Cooke JL. Depressed consciousness and coma. In: Marx JA, Hockberger RS, Walls RM, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 8th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 16.
Crocco TJ, Goldstein JN. Stroke. In: Marx JA, Hockberger RS, Walls RM, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 8th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 101.
DeLorenzo RA. Syncope. In: Marx JA, Hockberger RS, Walls RM, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 8th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 15.
Kleinman ME, Brennan EE, Goldberger ZD, et al. Part 5: adult basic life support and cardiopulmonary resuscitation quality: 2015 American Heart Association guidelines update for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2015;132(18 Suppl 2):S414-S435. PMID: 26472993
Review Date: 3/31/2017
Reviewed By: Jacob L. Heller, MD, MHA, Emergency Medicine, Virginia Mason Medical Center, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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