Fainting is a sudden loss of consciousness. It most often occurs when the blood pressure is too low (hypotension) and the heart does not pump a normal supply of oxygen to the brain. Typically, a faint lasts only a few seconds or minutes, and then the person regains consciousness.
The medical term for fainting is syncope (SIN koe pee). It is a common problem that affects one million people in the U.S. every year. About one-third of us will faint at least once during our lifetime. A single fainting spell usually is not serious. It may be explained by factors such as stress, grief, overheating, dehydration, exhaustion or illness.
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| If you faint suddenly and without explanation, however, contact your physician.
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Many causes of fainting, however, are not easy to explain.
Some are life-threatening.
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| People who have unexplained fainting spells may be told it is "all in your head." The causes of fainting often do not show up during a routine physical examination, but the problem usually is not psychological. It may be caused by a nervous system disorder, a heart problem, or by other underlying disease.
The trigger that causes a fainting spell may be as harmless as eating a meal, or so dangerous it causes the heart to stop. The most serious causes of syncope are related to heart damage or electrical system disorders that affect the heart's ability to pump blood efficiently. In some cases, fainting is the only warning sign of an abnormal heart rhythm (arrhythmia) that could cause sudden cardiac death.[more] |
| Some people with so-called "fainting disorders" do not actually faint. They may experience recurrent episodes of presyncope (signs such as nausea, dizziness or the feeling that they are about to faint) without losing consciousness. |
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| For most people, syncope is an unusual event. Some individuals, however, have frequent episodes of fainting. Syncope is a serious health problem that may be a symptom of life-threatening disease. Even when the cause is harmless, the results of fainting can be dangerous. People who lose consciousness without warning are at risk of hurting themselves or others. They may be unable to drive a car or hold down a job. Fainting is responsible for 6 percent of all emergency room visits and 3 percent of hospitalizations. |
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