Fainting and Loss of Consciousness

Many people feel lightheaded every once in a while, so lightheaded that they may faint — that is, pass out momentarily. Fainting is not the same as being asleep or unconscious. When a person faints, it’s usually temporary and the person can be revived in a few minutes. Someone who is unconsciousness, however, won’t respond to attempts to revive him. An unconscious person can’t cough or clear his throat, which can be dangerous if something is stuck in his throat or airway.

Fainting often results when blood flow to the brain is temporarily inadequate. This can happen as a result of stress, grief, overheating, dehydration, exhaustion, or illness; fainting may also occur after taking certain medications. Standing for an extended period in very hot weather — especially with locked knees — can also make people pass out. Inactivity can cause blood to settle in the lower parts of the body, reducing the amount of blood flowing into the brain.

Soldiers standing at attention for long periods are prone to fainting, for example. Certain medications can lower blood pressure to a level that will trigger fainting. People with diabetes can sometimes lose consciousness if their blood sugar levels are too high or too low.

Many people recover very quickly from a brief loss of consciousness without any harmful consequences. However, on some occasions, fainting can signal a medical emergency. Don’t treat fainting as minor unless you’re certain there is no serious underlying cause.

Warning signs

You may be able to tell when someone is about to faint. The warning signs include:

  • Pale, cool, and sweaty skin
  • Lightheadedness or dizziness
  • A slow pulse
  • Nausea
  • Frequent yawning
  • Feeling of restlessness
  • Tightness in the chest
  • Palpitations

When these signs appear, it is important to lie down or to sit down and put your head between your legs. That’s usually enough to restore adequate blood flow to the brain. If it is very hot, try to move to a cooler location.

Loss of consciousness that lasts for more than a minute or two can be serious, however. Often it is a sign of a serious medical problem, such as seizure, serious blow to the head, concussion, heart attack, diabetic coma, epilepsy, or another condition. It is important to treat someone who has fainted or lost consciousness with care to avoid injury. If someone remains unconscious for more than a minute, get help as quickly as possible.

What to do when a victim does not regain consciousness quickly

If you suspect that the cause is excessive heat, move the person to a cooler place. Lay the person on her back, elevating the legs eight to 12 inches. This will help blood flow to the brain. Wipe her forehead with a cool damp cloth. Loosen any tight clothing, especially at the neck and waist. If she is alert, give her a sports drink such as Gatorade or a glass of water with a teaspoon of salt. Also, make sure there is plenty of fresh air, particularly if you suspect carbon monoxide poisoning. Check the ABCs — airway, breathing, and circulation. Gently tilt the victim’s head back, lifting the chin. This will help air get through the nose and mouth. Put your ear to the person’s mouth to make sure you can hear breathing. If the victim is not breathing, call 911 and begin cardiopulmonary resuscitation (CPR) immediately.

If the victim vomits, roll her onto her side to prevent her from choking. Check for injuries, especially if the person has fallen. If the victim is bleeding or injured, begin appropriate first aid.


Because it is scary when someone does not quickly regain consciousness, some people panic and do the wrong thing. Remember:

  • Do not slap, shake, or throw water on the victim.
  • Do not place a pillow under the head.
  • Do not give anything to drink. One exception may be people with diabetes. If a diabetic person’s blood sugar is low, they may need to drink or eat something that will raise it immediately, such as nondiet soda or juice. If blood sugar is too high, the person will need an insulin shot. If he or she doesn’t have an injection available, call for medical help. If you are unsure if the problem is high or low blood sugar, give the victim something sweet to eat or drink while you wait for help.
  • Do not attempt to move a person unnecessarily.
  • Do not try to make an unconscious person sit or stand up.
  • Never leave an unconscious person unattended at any time. If necessary, ask someone else to call 911.

When to call 911

When someone has fainted, call emergency services if the person:

  • Is not breathing
  • Fell from a height or is injured and bleeding
  • Is known to have diabetes
  • Is pregnant or is over 50 years old
  • Feels chest pain, chest pressure, or chest discomfort, or has a pounding or irregular heartbeat
  • Can’t speak or has difficulty speaking, can’t move or “feel” a limb, is confused, has numbness and tingling, or has blurred vision these are symptoms of a possible stroke
  • Has convulsions, tongue trauma, or loss of bowel control
  • Fails to regain consciousness after two minutes

What to do

  • While you’re waiting for help, check the victim’s airways, breathing, and circulation.
  • Check for medical identification that would indicate a medical problem such as diabetes, epilepsy, or drug allergies. Alert the emergency personnel if the person has a medical condition.


American Medical Association. Handbook of First Aid and Emergency Care.

American College of Emergency Physicians. First Aid Manual.

The American Red Cross First Aid & Safety Handbook.

Emedicine Consumer Health. Heath Exhaustion and Heat Stroke Treatment http://www.emedicinehealth.com/articles/6209-6.asp

Emedicine Consumer Health. Fainting. http://www.emedicinehealth.com/articles/11007-2.asp

MayoClinic.com Fainting. http://www.mayoclinic.com/findinformation/firstaidandselfcare/index.cfm

Heart Rhythm Society. Fainting (Syncope). http://www.hrspatients.org/patients/signs_symptoms/fainting/default.asp

Heart Rhythm Society. Cardiovascular Syncope. http://www.hrspatients.org/patients/signs_symptoms/fainting/cardiovascular.asp

Medline Plus. National Institutes of Health. Unconsciousness: First aid. http://www.nlm.nih.gov/medlineplus/ency/article/000022.htm

Medline Plus. National Institutes of Health. Heat Emergencies. http://www.nlm.nih.gov/medlineplus/ency/article/000056.htm

Merck Manual Second Home Edition. Fainting. http://www.merck.com/mmhe/sec03/ch023/ch023b.html

Johns Hopkins University Children’s Center, Chronic Fatigue Clinic. General Information Brochure on Orthostatic Intolerance and its Treatment. Fhttp://www.pediatricnetwork.org/medical/OI/johnshopkins.htm

Mayo Clinic. Fainting: First Aid. http://www.mayoclinic.com/health/first-aid-fainting/FA00052

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