Unconsciousness is when a person suddenly becomes unable to respond to stimuli and appears to be asleep. A person may be unconscious for a few seconds — as in fainting — or for longer periods of time.

People who become unconscious don’t respond to loud sounds or shaking. They may even stop breathing or their pulse may become faint. This calls for immediate emergency attention. The sooner the person receives emergency first aid, the better their outlook will be.

Unconsciousness can be brought on by a major illness or injury, or complications from drug use or alcohol misuse.

Common causes of unconsciousness include:

A person may become temporarily unconscious, or faint, when sudden changes occur within the body. Common causes of temporary unconsciousness include:

Symptoms that may indicate that unconsciousness is about to occur include:

If you see a person who has become unconscious, take these steps:

  • Check whether the person is breathing. If they’re not breathing, have someone call 911 or your local emergency services immediately and prepare to begin CPR. If they’re breathing, position the person on their back.
  • Raise their legs at least 12 inches above the ground.
  • Loosen any restrictive clothing or belts. If they don’t regain consciousness within one minute, call 911 or your local emergency services.
  • Check their airway to make sure there’s no obstruction.
  • Check again to see if they’re breathing, coughing, or moving. These are signs of positive circulation. If these signs are absent, perform CPR until emergency personnel arrive.
  • If there’s occurring, place direct pressure on the bleeding area or apply a tourniquet above the bleeding area until expert help arrives.

CPR is a way to treat someone when they stop breathing or their heart stops beating.

If a person stops breathing, call your local emergency services or ask someone else to. Before beginning CPR, ask loudly, “Are you OK?” If the person doesn’t respond, begin CPR.

  1. Lay the person on their back on a firm surface.
  2. Kneel next to their neck and shoulders.
  3. Place the heel of your hand over the center of their chest. Put your other hand directly over the first one and interlace your fingers. Make sure that your elbows are straight and move your shoulders up above your hands.
  4. Using your upper body weight, push straight down on their chest at least 1.5 inches for children or 2 inches for adults. Then release the pressure.
  5. Repeat this procedure again up to 100 times per minute. These are called chest compressions.

To minimize potential injuries, only those trained in CPR should perform rescue breathing. If you haven’t been trained, perform chest compressions until medical help arrives.

If you’re trained in CPR, tilt the person’s head back and lift the chin to open up the airway.

  1. Pinch the person’s nose closed and cover their mouth with yours, creating an airtight seal.
  2. Give two one-second breaths and watch for their chest to rise.
  3. Continue alternating between compressions and breaths — 30 compressions and two breaths — until help arrives or there are signs of movement.

If unconsciousness is due to low blood pressure, a doctor will administer medication by injection to increase blood pressure. If low blood sugar level is the cause, the unconscious person may need something sweet to eat or a glucose injection.

Medical staff should treat any injuries that caused the person to become unconscious.

Potential complications of being unconscious for a long period of time include coma and brain damage.

A person who received CPR while unconscious may have broken or fractured ribs from the chest compressions. The doctor will X-ray the chest and treat any fractures or broken ribs before the person leaves the hospital.

Choking can also occur during unconsciousness. Food or liquid may have blocked the airway. This is particularly dangerous and could lead to death if it isn’t remedied.

The outlook will depend on what caused the person to lose consciousness. However, the sooner they receive emergency treatment, the better their outlook will be.