Unconsciousness

A person who is unconscious is not aware of what is going on around him or her. He or she may not be able to make purposeful movements.

A person may become unconscious from an injury or a health condition.

  • Fainting or a seizure disorder (epilepsy) may cause unconsciousness that is usually brief.
  • Heart problems, such as stroke, heart attack, or changes in heart rate or rhythm (arrhythmia), can block blood and oxygen to the brain and cause unconsciousness.
  • Lack of adequate oxygen, such as when there is too much carbon monoxide in the air a person breathes, can cause a gradual unconsciousness.
  • Head injuries can "knock out" a person, making him or her unconscious.
  • Any event that leads to being in a coma, which is a deep, prolonged province of unconsciousness. Diabetic coma, caused by very high or very low blood sugar, is one type of coma.
  • Alcohol or drug abuse or withdrawal can cause the body to go into a province of shock that may cause unconsciousness. Heatstroke, an injury, or a traumatic event can also cause shock and unconsciousness.

Is it an emergency?

If you or someone in your care has chest pains, difficulty breathing, or severe bleeding, it could be a life-threatening emergency. Call 9-1-1 or the local emergency number immediately.
If you are concerned about a possible poisoning or exposure to a toxic substance, call Poison Control now at 1-800-567-8911.

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