Unconsciousness - first aid: MedlinePlus Mobile Medical Encyclopedia

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 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:

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

Wrong answers or an inability to answer the question suggest a change in mental status.

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)
Lightheadedness
Loss of bowel or bladder control (incontinence)
Rapid heartbeat (palpitations)
Stupor

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.

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: 7/16/2011
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.