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:

• What is your name?
• What is the date?
• How old are you?

Wrong answers or an inability to answer suggest a change in 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).

• Unresponsiveness (does not respond to activity, touch, or other stimulation)
• Confusion
• Light-headedness
• Rapid heart beat (palpitations)
• Headache
• Drowsiness
• Stupor

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 found (as long breathing continues). If the person vomits, roll the entire body at one time to the side. Support the neck and back to keep 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 consciousness returns.

• 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.

Call 911 if the person is unconscious and:

• Is not breathing
• Does not return to consciousness quickly (within a couple of minutes)
• Fell down or has been injured, especially if bleeding
• Has diabetes
• Is pregnant
• Is over age 50
• Feels chest pain, chest pressure, chest discomfort, or has a pounding or irregular heartbeat
• Can't speak, has vision problems, or can't move the arms or legs
• Has seizures
• Loss of bowel control

• People with known medical conditions, such as diabetes, should always wear a medical alert tag or bracelet.
• Avoid situations where your blood sugar level gets too low.
• Avoid standing in one place too long without moving, especially if prone to fainting.
• If you feel like you are about to faint, lie down or sit with your head bent forward between you knees.

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.