Considerations

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.

Causes

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).

Symptoms

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:

• Confusion
• Drowsiness
• Headache
• Inability to speak or move parts of his or her body (see stroke symptoms)
• Light-headedness
• Loss of bowel or bladder control (incontinence)
• Rapid heartbeat (palpitations)
• Stupor

First Aid

1. Call or tell someone to call 911.
2. Check the person's airway, breathing, and pulse frequently. If necessary, begin rescue breathing and CPR.
3. If the person is breathing and lying on the back, and you do not think there is a spinal injury, carefully roll the person toward you onto the side. Bend the top leg so both hip and knee are at right angles. Gently tilt the head back to keep the airway open. If breathing or pulse stops at any time, roll the person on to his back and begin CPR.
4. If you think there is a spinal injury, leave the person where you found them (as long as breathing continues). If the person vomits, roll the entire body at one time to the side. Support the neck and back to keep the head and body in the same position while you roll.
5. Keep the person warm until medical help arrives.
6. If you see a person fainting, try to prevent a fall. Lay the person flat on the floor and raise the feet about 12 inches.
7. If fainting is likely due to low blood sugar, give the person something sweet to eat or drink when they become conscious.

DO NOT

• DO NOT give an unconscious person any food or drink.
• DO NOT leave the person alone.
• DO NOT place a pillow under the head of an unconscious person.
• DO NOT slap an unconscious person's face or splash water on the face to try to revive him.

When to Contact a Medical Professional

Call 911 if the person is unconscious and:

• Does not return to consciousness quickly (within a minute)
• Has fallen down or been injured, especially if bleeding
• Has diabetes
• Has seizures
• Has lost bowel or bladder control
• Is not breathing
• Is pregnant
• Is over age 50

Call 911 if the person regains consciousness but:

• Feels chest pain, pressure, or discomfort, or has a pounding or irregular heartbeat
• Can't speak, has vision problems, or can't move the arms and legs

Prevention

• Avoid situations where your blood sugar level gets too low.
• Avoid standing in one place too long without moving, especially if you are prone to fainting.
• Get enough fluid, particularly in warm weather.
• If you feel like you are about to faint, lie down or sit with your head bent forward between your knees.

People with known medical conditions, such as diabetes, should always wear a medical alert tag or bracelet.

Alternative Names

Loss of consciousness - first aid; Coma - first aid; Mental status change; Altered mental status

References

Cooke JL. Depressed consciousness and coma. In: Marx JA, Hockberger RS, Walls RM, et al, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 7th ed. Philadelphia, Pa: Mosby Elsevier; 2009:chap 14.

Biros MH, Heegaard WG. Head injury. In: Marx JA, Hockberger RS, Walls RM, et al, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 7th ed. Philadelphia, Pa: Mosby Elsevier; 2009:chap 38.

Kothari RU, Crocco TJ, Barsan WG. Stroke. In: Marx J, ed. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 6th ed. Philadelphia, Pa: Mosby Elsevier; 2006: chap 99.

Update Date: 4/16/2012

Reviewed by: Jacob L. Heller, MD, MHA, Emergency Medicine, Virginia Mason Medical Center, Seattle, Washington, Clinic. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.