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 (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 abuse.
Common causes of unconsciousness include:
- a car accident
- severe blood loss
- a blow to the chest or head
- a drug overdose
- alcohol poisoning
A person may become temporarily unconscious (faint) when sudden changes occur within the body. Common causes of temporary unconsciousness include:
- low blood sugar
- low blood pressure
- syncope (loss of consciousness due to lack of blood flow to the brain)
- problems with the heart’s rhythm
- neurologic syncope (loss of consciousness caused by a seizure, stroke, or transient ischemic attack)
Symptoms that may indicate that unconsciousness is about to occur include:
- sudden inability to respond
- slurred speech
- a rapid heartbeat
- dizziness or lightheadedness
If you see a person who has become unconscious, take these steps:
- Check whether the person is breathing. If they are not breathing, have someone call 911 immediately. If they are breathing, position the person on their back.
- Raise the person’s legs at least 12 inches above the ground.
- Loosen any restrictive clothing or belts. If the person doesn’t regain consciousness within one minute, call 911.
- Check the person’s airway to make sure there’s no obstruction.
- Check again to see if the person is breathing, coughing, or moving. These are signs of positive circulation. If these signs are absent, perform cardiopulmonary resuscitation (CPR) until emergency personnel arrive.
Cardiopulmonary resuscitation (CPR) is a way to treat someone when they stop breathing or their heart stops beating.
If a person stops breathing, call 911 or ask someone else to. Before beginning CPR, ask loudly, “Are you okay?” If the person doesn’t respond, begin CPR.
- Lay the person on their back on a firm surface.
- Kneel next to the person’s neck and shoulders.
- Place the heel of your hand over the center of the person’s 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.
- Using your upper body weight, push straight down on the person’s chest at least 1.5 inches for children, or 2 inches for adults. Then release the pressure. 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 are trained in CPR, tilt the person’s head back and lift the chin to open up the airway.
- Pinch the person’s nose closed and cover their mouth with yours, creating an airtight seal.
- Give two one-second breaths and watch for the person’s chest to rise.
- 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, they 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:
- brain damage
If you received CPR while unconscious, you may have broken or fractured ribs from the chest compressions. Your doctor will X-ray your chest and treat any fractures or broken ribs before you leave the hospital.
Choking can also occur during unconsciousness. Food or liquid may have blocked your airway. This is particularly dangerous and could lead to death if it isn’t remedied.
Your outlook will depend on what caused you to lose consciousness. However, the sooner you receive emergency treatment, the better your outlook will be.