Fainting - Overview
Passed out; Light-headedness - fainting; Syncope; Vasovagal episode
Definition of Fainting:
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. You may feel light-headed or dizzy before fainting.
A longer, deeper state of unconsciousness is often called a coma.
When you faint, you not only lose consciousness, but you also lose muscle tone and the color in your face (pallor). You may also feel weak or nauseated just before fainting. You may have the sense that noises are fading into the background.
Fainting may occur while you:
- Cough very hard
- Have a bowel movement (especially if you are straining)
- Have been standing in one place for too long
Fainting can also be related to:
- Emotional distress
- Severe pain
Other causes of fainting:
- Certain medications, including those used for anxiety, depression, high blood pressure, and allergies (these drugs may cause a drop in blood pressure)
- Drug or alcohol use
- Low blood sugar
- Sudden drop in blood pressure (such as from bleeding or being severely dehydrated)
- Standing up very suddenly from a lying position
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 and less likely in those younger than 40.
- Reviewed last on: 5/29/2011
- David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
Calkins H, Zipes DP. Hypotension and syncope. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 42.
Simon RP. Syncope. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 427.
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