Loss of consciousness - first aid; Coma - first aid; Mental status change; Altered mental status; Syncope - first aid; Faint - first aid
Unconsciousness is when a person is unable to respond to people and activities. Health care providers 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 unexplained change in mental status must be treated as a medical emergency.
Unconsciousness can be caused by nearly any major illness or injury. It can also be caused by substance (medicine or 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 provider can determine if the affected person needs tests to diagnose their fainting.
Other causes of fainting include straining during a bowel movement or urination, coughing very hard, breathing very fast (hyperventilating), or vasovagal syncope.
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.
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:
Call or tell someone to call 911 or the local emergency number.
If the person is unconscious from choking:
Call 911 or the local emergency number if the person is unconscious and:
Call 911 or the local emergency number if the person regains consciousness, but:
To prevent becoming unconscious or fainting:
If you have a medical condition, such as diabetes, always wear a medical alert necklace or bracelet.
Hewett Brumberg EK, Douma MJ, Alibertis K, et al. American Heart Association and American Red Cross. 2024 American Heart Association and American Red Cross guidelines for first aid. Circulation. 2024;150(24):e519-e579. PMID: 39540278 pubmed.ncbi.nlm.nih.gov/39540278/.
Lei C, Smith C. Depressed consciousness and coma. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 12.
Perman SM, Elmer J, Maciel CB, et al. 2023 American Heart Association focused update on adult advanced cardiovascular life support: An update to the American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2023;149(5):e254-e273. PMID: 38108133 pubmed.ncbi.nlm.nih.gov/ 38108133/.
Probst M. Syncope. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 11.
BACK TO TOPReview Date: 1/8/2025
Reviewed By: Jesse Borke, MD, CPE, FAAEM, FACEP, Attending Physician at Kaiser Permanente, Orange County, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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