What is Fainting?

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  • Written By: Tricia Ellis-Christensen
  • Edited By: O. Wallace
  • Last Modified Date: 02 October 2016
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Fainting is a generally brief and unexpected loss of consciousness that may be caused by a variety of factors. Sometimes loss of consciousness does not indicate severe problems, and other times it may suggest certain dangerous physiological factors.

Often people describe initial fainting symptoms as feeling hot, possibly hearing a rushing sound, feeling dizzy, and seeing spots. These symptoms if quickly addressed may help a person remain conscious. Usually it is recommended that people lie on the floor with the feet elevated slightly.

In some cases, fainting simply occurs too quickly to stop. Before a person knows it, they may simply wake up on the floor a few seconds after having lost consciousness. This can be disorienting, since the person’s memory of how they got on the floor may be affected and it may be hard to understand what just happened.

There are many causes of fainting, which makes identifying cause difficult at times. Some common causes are extreme emotional stress, too little food or drink resulting in low blood sugar or dehydration, normally low blood pressure, excessive physical activity, straining with a bowel movement then standing up quickly, or simply standing up too quickly. Medical causes may include arrhythmias, heart attack, stroke, severe injury, or conditions like narrowing of the aortic valve.


Fainting is broken into several groups often defined by cause, and is often called “syncope.” Vasovagal syncope tends to occur when blood pressure or heart rate lower significantly. Some people tend to have vasovagal reactions to stress, as from seeing blood, getting hurt, or seeing someone else get hurt. This type of episode, when vasovagal syndrome is known, is usually not dangerous.

Pressure, externally on the nerves surrounding the carotid arteries can lead to carotid sinus syncope. Some people have very sensitive nerve endings around their carotid arteries, which may cause even a small amount of pressure to result in a loss of consciousness.

In some cases, fainting can occur directly after using the bathroom. When the condition occurs after someone urinates it is called micturition syncope. Other forms have been linked to excessive coughing, or even excessive laughing. In most of these cases, the blood pressure quickly and momentarily drops, causing loss of consciousness.

Sometimes fainting can indicate a serious condition like stroke or heart attack. If consciousness is not restored in a few seconds, then one should alert a physician immediately. This is particularly the case if the person has seemed unduly upset prior to the loss of consciousness, is elderly, or has a known cardiac condition.


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Post 1

Can you faint because of locking your knees while standing for an extensive period of time? Does this decrease blood flow to the brain enough to cause a person to faint?

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