Fainting is a brief loss of consciousness due to a drop in blood flow to the brain. The episode lasts less than a couple of minutes and you recover from it quickly and completely. The medical name for fainting is syncope.
When you faint, you not only lose consciousness, you also lose muscle tone and the color in your face. Before fainting, you may also feel weak, nauseated, and have the sense that your vision is constricting (tunnel vision) or noises are fading into the background.
Fainting may occur while or after you:
Fainting can also be related to:
Other causes of fainting:
Less common but more serious reasons for fainting include heart disease (such as abnormal heart rhythm or heart attack) and stroke. These conditions are more likely in persons over age 65.
If you have a history of fainting, follow your doctor's instructions for how to prevent fainting. For example, if you know the situations that cause you to faint, avoid or change them.
Get up from a lying or seated position slowly. If having blood drawn makes you faint, tell your health care provider before having a blood test and make sure that you are lying down when the test is done.
You can take immediate treatment steps when someone has fainted:
Call 911 if the person who fainted:
Even if it is not an emergency situation, you should be seen by a doctor if you have never fainted before, if you faint often, or if you have new symptoms with fainting. Call for an appointment to be seen as soon as possible.
Your health care provider will ask you questions to determine whether you simply fainted, or if something else happened (such as a seizure or heart rhythm disturbance), and to figure out the cause of the fainting episode. If someone witnessed the fainting episode, their description of the event may be very helpful.
Questions will include:
The physical examination will focus on your heart, lungs, and nervous system. Your blood pressure may be measured while you are in several different positions. People with a suspected arrhythmia may need to be admitted to a hospital for testing.
Tests that may be ordered include:
Passed out; Light-headedness - fainting; Syncope; Vasovagal episode
Goldman L. Approach to the patient with possible cardiovascular disease. In: Goldman L, Schafer AI, eds. Goldman’s Cecil Medicine. 24th ed. Philadelphia, Pa.: Elsevier Saunders; 2011:chap 83.
Olgin JE. Approach to the patient with suspected arrhythmia. In: Goldman L, Schafer AI, eds. Goldman’s Cecil Medicine. 24th ed. Philadelphia, Pa.: Elsevier Saunders; 2011:chap 62.
Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.
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