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Fainting is a common symptom in the elderly, generally referred to in the medical literature as syncope. Fainting is defined as transient loss of consciousness accompanied by loss of postural tone, with spontaneous recovery, not requiring resuscitation. Fainting has multiple underlying causes. This common symptom has potential adverse consequences, such as falls, fractures, brain injury, soft tissue injuries, and anxiety, which particularly in the elderly may lead to loss of independent function. When the reason for fainting is an underlying heart disease, an increased risk of sudden death is suggested; but when fainting is unexplained after thorough initial evaluation and recurrent then there is no such increased risk.

A person who faints may have some convulsions but recovers quickly and is not confused for more than a few minutes, whereas a person with epilepsy will usually have more prolonged convulsions and be confused for a longer time. In coma the heart beats and the person breathes but consciousness is not regained as quickly.

Basic mechanisms and predisposition in elderly people

Fainting results from inadequate energy substrate delivery to the brain. The major energy substrates are oxygen and glucose. Significant lowering of blood sugar tends to result in coma rather than fainting, and a prolonged cessation of oxygen delivery results in death. Thus transient loss of delivery of oxygen to the brain due to decreased blood flow to the brain is the final common pathway in most causes of fainting. Generalized lowering of oxygen in the blood from heart or lung disease or reduced oxygen-carrying capacity of the blood from anemia are risk factors for fainting, particularly in the elderly, but rarely the sole cause.

Blood pressure lowered enough to decrease blood flow to the brain may cause fainting, and the causes of fainting can be deduced from the blood pressure formula. Blood pressure is the product of cardiac output and total peripheral resistance of the arteries. Cardiac output is the product of stroke volume and heart rate per minute. Stroke volume is the amount of blood that the heart ejects in one beat. Total peripheral resistance is a measure of how constricted the arterial blood vessels are. Thus anything that will reduce the volume of blood that is ejected, impair heart rate, or cause dilatation of the arteries may lead to a fainting spell.

Elderly people are predisposed to fainting by the presence of multiple abnormalities, both age- and disease related. These conditions add up to threaten cerebral blood flow or reduce oxygen content in the blood. A situational stress that further reduces blood pressure, such as standing up from a lying position or straining at stools or voiding, may reduce cerebral oxygen delivery below the critical threshold and result in fainting. Several homeostatic mechanisms that normally preserve blood pressure and cerebral oxygen delivery in the face of stress become impaired with age. These mechanisms include cerebral blood flow autoregulation, blood pressure sensors in the carotid artery (baroreflexes), relaxation of the heart muscle, and sodium conservation by the kidneys.


Multiple studies have shown that 20 to 30 percent of fainting episodes have cardiac causes, 10 to 20 percent have other causes, and 30 to 50 percent remain unexplained in spite of extensive evaluation.

Several cardiac diseases may cause fainting, such as those that cause mechanical obstruction to blood flow such as narrowing of heart valves or abnormal thickening of the heart muscle, called cardiomyopathy. Blood clots from veins of the body, most often the legs, may also present with fainting due to obstruction of blood flow through the lungs and heart. Both slow heart rate (less than 40 beats per minute) and rapid heart rate (more than 140 beats per minute) may cause fainting. The rapid heart rate causes fainting by not giving the heart enough time to fill with blood before ejection into the circulation. The causes of these heart rate abnormalities include heart attacks, disease of the conduction system of the heart, and diseasemost often seen in the elderlyof the sinus node of the heart, where the origin of the heart beat occurs normally.

Orthostatic hypotension is a term for blood pressure that drops more than 20 mm of mercury on position change, such as standing up from a lying or sitting position. This may cause dizziness when in mild stages but frequently causes elderly people to faint. It is either due to volume depletion or inability to constrict blood vessels under this type of stress. Volume depletion may be caused by fluid loss or blood loss or by too little fluid intake, or by medications such as diuretics, which increase excretion of fluid through the kidneys. Dilatation of the blood vessels may be caused by prolonged inactivity, such as bed rest, or by medications such as blood pressure lowering medications and the older types of medications prescribed for depression. By only giving the lowest effective dose of medications to the elderly person, these types of adverse effects may be avoided or corrected. Disturbed autonomic function may cause dilatation of the blood vessels and cause fainting. Examples of these are central nervous system diseasessuch as Multiple System Atrophy, Parkinson's disease, or Dementia with Lewy Bodiesand peripheral autonomic neuropathies caused by diseases such as diabetes mellitus or amyloidosis. Digestion of food may lead to hypotension and fainting in the elderly person due to inability to compensate for blood pooling in the gut during digestion, so-called postprandial hypotension. Finally, reflexes may cause dilatation of blood vessels, triggered by straining at stools, urination, swallowing, or coughing or by hypersensitivity of the carotid sinus, which is located in the neck.

Evaluation and treatment

The patient's history is the most important part of the evaluation, and the physical examination focuses on blood pressure and heart evaluation to exclude the life-threatening causes of fainting. Therapy should be directed toward minimizing multiple risks of fainting, avoiding toxic interventions, and treating specific symptomatic diseases (for example, with pacemakers for certain conduction diseases in the heart), while basing treatment on the underlying disease, rather than on age per se.

PÁlmi V. JÓnsson

See also Balance and Mobility; Dementia with Lewy Bodies; Dizziness; Epilepsy; Heart Disease; Multiple Systems Atrophy; Parkinsonism.


JÓnsson, P. V., and Lipsitz, L. A. "Dizziness and Syncope." In Principles of Geriatric Medicine and Gerontology, 3d ed. Edited by William R. Hazzard, Edwin L. Bierman, John P. Blass, Walter H. Ettinger, Jr., and Jeffrey B. Halter. McGraw-Hill Inc., 1994. Pages 11651181.

Linzer, M.; Yang, E. H.; Estes, N. A., III; Wang, P.; Vorperian, V. R.; and Kapoor, W. N. "Diagnosing Syncope. Part 2: Unexplained Syncope. Clinical Efficacy Assessment Project of the American College of Physicians." Annals of Internal Medicine 127, no. 1 (1997): 7686.

Shaw, F. E., and Kenny, R. A. "The Overlap between Syncope and Falls in the Elderly." Postgraduate Medical Journal 73, no. 864 (1997): 635639.


See Balance and mobility

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Fainting, referred to medically as syncope (sin-copee), is a sudden loss of consciousness caused by an interruption in the flow of blood and oxygen to the brain. It is not a separate disease but a symptom of an underlying condition or disease.


Losing consciousness or passing out can happen suddenly for a variety of reasons. Regardless of the cause, a fainting spell or syncope happens when not enough oxygen-rich blood is delivered to the brain, often related to changes in blood pressure . Sudden drops in blood pressure (orthostatic syncope) or a heart problem (cardiac, cardiovascular or cardiogenic syncope) can cause someone to faint; other reasons include physical exertion, a traumatic situation, overheating or dehydration . In each case, the individual's need for oxygen has changed suddenly and the body is not able to handle it. This happens commonly among senior adults, occurring either as a single episode or occurring repeatedly. Serious forms of fainting or syncope are usually related to a pre-existing heart disorder or the heart's inability to pump blood; this type of syncope can result in sudden death .

Types of syncope

Neurocardiogenic syncope occurs as a result of too little blood flowing to the brain without the presence of a specific heart problem. This type of syncope can involve unusual activity of nerves that control activity in the heart and lungs, which may produce an irregular heartbeat. The loss of consciousness usually lasts a few minutes, with the individual regaining consciousness and orientation at the same time. Neurocardiogenic syncope is the most common cause of all fainting episodes and occurs most often in young adults, who eventually outgrow the condition.

Vasovagal syncope is a form of neurocardiogenic syncope and the most common type among older individuals, even though more episodes actually occur among young people. Vasovagal episodes result from unusual activity of the vagus nerve, which starts in the brain and branches out to control nerve activity in the throat, lungs, heart and intestines. Vasovagal syncope is thought to be related to poor communication between the heart and brain. Sudden pain can produce this type of fainting spell, as well as fear or an upsetting incident. Usually, consciousness is quickly regained if the individual is placed in a horizontal lying-down position.

Situational syncope is another type of neurocardiogenic syncope and occurs in two forms. The first form is syncope that comes from unusual activity of the vagus nerve that controls activity in the heart and lungs. The fainting happens either during urination, especially when getting up during the night to urinate, or while moving the bowels. The second syncope takes place during coughing or swallowing or, rarely, during the presence of severe pain in the throat that spreads to the ear (glossopharyngeal neuralgia ). Unconsciousness during situational syncope lasts only a few seconds.

Cardiovascular syncope (or cardiogenic syncope) occurs suddenly as a result of an irregular heart beat (e.g., tachy- or brady-arrhythmias and fibrillation), a structural defect of the heart, or underlying chronic heart disease . This type of syncope occurs in cardiac situations that either block blood flow going into the heart or reduce blood flow coming out of the heart, reducing blood flow to the brain. This may happen during exercise or along with heart palpitations and is the most dangerous form of syncope.

Cerebrovascular syncope involves the brain stem and blockage of the arterial blood supply to the brain by blood clots (ischemic attack). People who are at risk for stroke (cerebrovascular accident) and who have other stroke-like symptoms, including pain in one arm, sensations of numbness in the face, or vision problems usually experience cerebrovascular syncope. Loss of consciousness can last from 30 minutes to one hour.

Orthostatic syncope is related to sudden changes in blood flow associated with heart attack (myocardial infarction), irregular heart rhythm (cardiac arrthythmias), high blood pressure (hypertension ), low blood pressure (hypotension) or when changing from a sitting or lying-down position to standing (orthostatic hypotension). Lying down relieves the fainting spell but underlying causes may need immediate treatment.

Psychiatric syncope is common in young individuals with psychological problems. Fainting spells may occur frequently. The syncope is usually accompanied by rapid open-mouth breathing and sometimes the eyes remain open. Psychiatric syncope often occurs in conjunction with an upsetting or traumatic situation.

Carotid artery (carotid sinus) syncope is the result of a branch of the carotid artery in the neck being squeezed shut (compressed) by a certain neck position. This prevents blood and oxygen from passing through the carotid artery into the brain and causes a fainting spell.


Different forms of syncope affect individuals of varying ages and, in some cases, men more than women. Syncope occurs twice as often in senior adults over age 70 and three to four times as often in those over age 80 than it does in young and middle-aged adults.

Neurocardiogenic syncope, the type without the presence of structural heart conditions, can occur in individuals of all ages, male or female, and all races, but is especially common, along with psychiatric syncope, in teenagers and young adults. Situational syncope is a specific form of neurocardiogenic syncope that affects primarily senior adults. Vasovagal syncope, a neurocardiogenic syncope considered a simple faint is the most common form, representing 25–40% of people who lose consciousness. Prevalence of other forms of syncope includes 1–8% situational, 0.4% carotid sinus, and 4–10% orthostatic or postural, related to reduced blood flow from the heart to the brain with changes in posture. Cardiovascular syncope represents 4–38% of patients with syncope. Most are men, parallel to the number of men with underlying heart disease and/or high blood pressure.

Causes and symptoms

A combination of several forms of syncope may cause fainting in senior adults, especially causes related to compromised functions of the heart, brain or nervous system due to underlying disease, and situational causes involving urination, bowel movements, coughing or swallowing. Vasovagal syncope may stem from emotional causes or pain conditions and happens when the individual is standing. Rapid loss of consciousness occurs in conjunction with cardiac arrhythmias , which causes fainting within four to eight seconds if the individual is standing, but within about 12 to 15 seconds if the patient is lying down. Orthostatic syncope may result after eating a heavy meal or after changes in posture from sitting or lyingdown to standing. Because older individuals are likely to be taking multiple drugs for various conditions, medications are often responsible for causing syncope by reducing blood pressure to lower-than-normal levels, which reduces oxygen to the brain. Drugs that may cause syncope include blood pressure medications, sedatives, antidepressants, and medicines for heart disease or Parkinson's disease. Losing a large quantity of blood or fluid loss from severe diarrhea can also cause syncope.

Symptoms of syncope that occur prior to fainting vary according to the type and cause and may include lightheadedness, dizziness , ringing in the ears, generalized weakness and vision problems. If there is no underlying heart disease, the individual feels light-headed or dizzy when the heart is not pumping enough blood to provide oxygen to the brain. If the heart attempts to increase blood pressure to direct blood to the brain, then extra pumping of the heart alerts the nervous system about an increase in blood pressure, which may result in nerve activity that actually reduces pressure suddenly, causing the fainting spell. The primary symptom is light-headedness.

Cardiovascular syncope caused by underlying heart disease may occur without warning and sudden fainting is the only symptom; when symptoms do warn of cardiovascular syncope, they may include sudden tightening in the chest, erratic beating of the heart such as fluttering or skipped beats, and rapid breathing or feelings of fear. Seizures can accompany syncope in some individuals. Healthy individuals may become dizzy and nauseous but may not actually lose consciousness; this is considered to be a fainting disorder but it is not classic syncope.


Since fainting does not typically happen in the doctor's office, the individual's history is the most important part of diagnosing syncope. The doctor will need to know when the fainting occurred and how many times, what symptoms or events preceded the fainting spell, how long the individual was unconscious, what is remembered of being unconscious (stiffening of the body, jerking of arms and legs, etc.) how the individual felt after regaining consciousness, and what position the individual was in when each fainting spell began. These questions help the doctor determine which type of syncope may be occurring. Symptoms preceding fainting are especially important and may include dizziness, light-headedness, nausea, ringing in the ears (tinnitus ), changes in vision, or heart symptoms such as rapid or irregular heart beat (palpitations). The doctor may ask what the individual was doing just prior to fainting such as physical activity, engaging in an upsetting or emotional situation, changing position from sitting or lying down to standing, or possibly straining while urinating. Each of these can indicate a different type of syncope; for example, fainting during demanding physical activity or when the individual feels an irregular heart beat suggests a cardiac cause and possible cardiovascular syncope.

Certain diagnostic testing may be done, depending on how the individual described what happened before, during and after the fainting spell. Electrocardiogram is used to evaluate heart function and risk or extent of heart disease. Blood pressure is taken, sometimes including blood pressure in the arms and legs (peripheral pressure). Laboratory blood work may be ordered, including a complete blood count (CBC), blood clotting tests (coagulation factors) and blood chemistry profile, which evaluate overall health, the amount of blood cells versus plasma (hematocrit) and signs of heart disease or possible risk for stroke.


Managing underlying diseases such as high blood pressure, low blood pressure, or coronary artery disease is the primary means of treating syncope. Heart valve replacement may be treatment for cardiovascular syncope or drugs to control the underlying heart problem. Pacemakers may be implanted to control arrhythmias that cause syncope. Neurocardiogenic syncope, which has no underlying heart disease, is treated by counseling the individual on lifestyle changes and how to avoid situational causes associated with syncope that happens during urination, coughing or swallowing. Drugs used to treat neurocardiogenic syncope include fludrocortisone to open blood vessels for better blood flow, midodrine to constrict blood vessels, antidepressants to help control nervous system response, and beta blockers to control blood pressure. Discontinuing drugs that are known to cause syncope is usually effective in stopping fainting episodes. Sometimes changing the time of day an individual takes medications may help. Certain physical measures such as wearing elastic compression stockings, sleeping in certain positions and doing exercises such as squatting may also be recommended for neurocardiogenic syncope.


  • What causes my fainting?
  • What should I do if I feel like I am going to faint?
  • Should I call you if I faint again?
  • Do many other people my age faint?
  • Is medication or other treatment available to stop the fainting spells?


Most fainting disorders or syncope can be managed with drugs or treating underlying diseases. No serious effects result in most cases. Risk of falls and physical injury during fainting spells is increased with all types of syncope. Primary risk factors for syncope are a history of an abnormal electrocardiogram, age older than 45, a history of congestive heart failure , and a history of cardiac arrhythmia, especially ventricular tachycardia . The presence of three risk factors has been shown to increase risk of death within one year of onset of syncope. Cardiovascular syncope is a serious condition related to heart arrhythmias or damage to heart structure and can result in sudden death.


Fainting, depending on the cause, may not be avoidable except by preventing the underlying disease. Managing high or low blood pressure, for example, may prevent orthostatic syncope. Prevention or reduction of blood clot formation, cardiovascular conditions, stroke and heart disease involves regular care and advice by a physician, as well as lifestyle and dietary measures, which together may help to prevent recurrence of fainting. Avoiding physical exertion, especially in hot weather, may reduce the risk of fainting spells in some individuals.


Fibrillation —An irregular heart beat caused by rapid twitching of tiny fibers in the heart muscle; it can occur in the atrial or ventricular portions of the heart (atrial fibrillation, ventricular fibrillation).

Glossopharyngeal neuralgia —Stabbing pain that occurs in the mouth and throat and may radiate up to the ear; it is caused by spasm of the glossopharyngeal nerve that helps control the tongue and pharynx in the throat.

Ischemia (ischemic) —Refers to a form of localized anemia resulting from lack of blood to a specific area of the body, which can cause tissue death in the area.

Orientation —The ability of individuals to sense their own physical presence in a specific space or environment.

Tachycardia —An irregularity in heart rhythm in which the heartbeat can increase to rates over 100 beats per minute.

Caregiver concerns

Fainting may be a sign of a serious or life-threatening illness. Caregivers should report fainting spells to the patient's physician so that the underlying illness can be identified. Although some types of fainting are not dangerous, they can lead to falls or injury to the patient or other people due to losing control of a car, tools or machinery. Caregivers must ensure that the patient avoids using stairs and ladders and does not drive a car or walk outside the home alone. Slippery floor surfaces must be avoided as well. Because certain medications may cause fainting, caution must be taken to avoid overdosing. Caregivers need to ensure that all drug dosages are accurate and medications are taken at the appropriate time.



Simon, R. P. “Syncope.” Cecil Medicine, 23rd ed. R. Goldman, ed. Philadelphia: Saunders, 2007: 1492–1432.


Ebell, M. H. “Syncope: Initial Evaluation and Prognosis.” American Family Physician 74, no. 8 (2006).


“Fainting (Syncope).” Aging in the Know. February 25, 2005 [cited April 6, 2008]. Foundation for Health in Aging, American Geriatric Society. http://www.healthinaging.org/agingintheknow/chapters_ch_trial.asp?ch=24#top.

“Fainting (Syncope).” Patient and Public Information Center. [cited April 6, 2008]. Heart Rhythm Society. http://www.hrspatients.org/patients/signs_symptoms/fainting/default.asp.


American Geriatric Society, Empire State Building 350 Fifth Avenue, Suite 801, New York, NY, 10118, (800) 563-4916, (212) 832-8646, [email protected], http://www.healthinaging.org.

Heart Rhythm Society, 1400 K Street NW, Washington, D.C., 20005, (202) 464-3400, (202) 464-3401, [email protected], http://www.hrspatients.org.

L. Lee Culvert

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Fainting is loss of consciousness caused by a temporary lack of oxygen to the brain. Known by the medical term "syncope," fainting may be preceded by dizziness, nausea, or a feeling of extreme weakness.


When a person faints, the loss of consciousness is brief. The person will wake up as soon as normal blood flow is restored to the brain. Blood flow is usually restored by lying flat for a short time. This position puts the head on the same level as the heart so that blood flows more easily to the brain.

A fainting episode may be completely harmless and of no significance, but it can be a symptom of a serious underlying disorder. No matter how trivial it seems, a fainting episode should be treated as a medical emergency until the cause is determined.

Causes and symptoms

Extreme pain, fear, or stress may bring on fainting. This type of fainting is caused by overstimulation of the vagus nerve, a nerve connected to the brain that helps control breathing and circulation. In addition, a person who stands still or erect for too long may faint. This type of fainting occurs because blood pools in the leg veins, reducing the amount that is available for the heart to pump to the brain. This type of fainting is quite common in older people or those taking drugs to treat high blood pressure.

When an older person feels faint upon turning the head or looking upward suddenly, the cause could be osteoarthritis of the neck bones. Osteoarthritis damages the cartilage between the neck bones and causes pressure on blood vessels leading to the brain.

Fainting can be a symptom of a disease such as Stokes-Adams syndrome, a condition in which blood flow to the brain is temporarily reduced because of an irregular heartbeat. Some people may experience fainting associated with weakness in the limbs or a temporary problem in speaking caused by obstructed blood flow in vessels passing through the neck to the brain. Pregnant women frequently feel faint. Fainting may also occur as a result of low blood sugar. Low blood sugar can occur if a person skips a meal or has diabetes.

Fainting can also be caused by:

  • prolonged coughing
  • straining to defecate or urinate
  • blowing a wind instrument too hard
  • remaining in a stuffy environment with too little oxygen

Sometimes fainting may be caused by a temporary drop in the blood supply to the brain caused by a transient ischemic attack (TIA). A TIA, sometimes called a mini-stroke, is a disruption in the blood supply to the brain caused by a blocked or burst blood vessel. Seek help immediately if a fainting spell is followed by one or more of the symptoms listed below:

  • numbness or tingling in any body part
  • blurred vision
  • confusion
  • difficulty speaking
  • loss of movement in arms or legs

A few seconds before fainting, a person may sweat or become pale, feel nauseated or dizzy, and have blurred vision or racing heartbeat. Once the person loses consciousness, the pupils may dilate as the heart rate slows down. There may be abnormal movements. Muscles may tighten or the back may arch. These movements do not last long and they are not violent.

In most cases, the patient regains consciousness within a few minutes, but the fainting spell may be followed by nervousness, headache, nausea, dizziness, pallor or sweating. The person may faint again, especially if he or she stands up within 30 minutes.


Most episodes of fainting are a one-time occurrence. When a person experiences repeated fainting spells, a physician should be consulted.


Most of the time, a person who faints ends up lying on the floor. If this happens, the patient should be rolled onto his or her back. Because someone who faints often vomits, bystanders should keep the airway open. A person who is fainting should not be held upright or in a sitting position. These positions prevent blood flow to the brain and may bring on a seizure.

Bystanders should check the patient's breathing and pulse rate. The pulse may be weak and slow. If there are no signs of breathing or heart rate, the problem is more serious than fainting, and cardiopulmonary resuscitation (CPR ) must begin.

If breathing and pulse rates seem normal, the person's legs should be raised above the level of the head so that gravity can help the blood flow to the brain. Belts, collars or any other constrictive clothing should be loosened.

If the person does not regain consciousness within a minute or two after fainting, medical help should be summoned.


After a fainting spell, the person should regain normal color but may continue to feel weak for a short time. Lying down quietly for a few moments may help.

In most cases, an attack of fainting is not serious. As soon as the underlying pain or stress passes, the danger of repeated episodes also is eliminated.


If a person is feeling faint, unconsciousness may be prevented by sitting with the head between the knees or lying flat with the legs raised.

A person who has fainted should lie flat for 10-15 minutes after regaining consciousness to give the system a chance to regain its balance. Standing up too soon may bring on another fainting spell.



Greenberg, David A., et al. Clinical Neurology. 2nd ed. Norwalk, CT: Appleton & Lange, 1993.


Osteoarthritis A disease characterized by damage to the cartilage in the joints. The joints become inflamed, deformed, and enlarged, and movement becomes painful.

Stokes-Adams syndrome Recurrent episodes of temporary loss of consciousness (fainting) caused by an insufficient flow of blood from the heart to the brain. This syndrome is caused by a very rapid or a very slow heartbeat.

Transient ischemic attack (TIA) A brief interruption of the blood supply to part of the brain that causes a temporary impairment of vision, speech, or movement. Usually, the episode lasts for just a few moments, but it may be a warning sign for a full-scale stroke.

Vagus nerve A cranial nerve, that is, a nerve connected to the brain. The vagus nerve has branches to most of the major organs in the body, including the larynx, throat, windpipe, lungs, heart, and most of the digestive system.

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Fainting is a temporary loss of consciousness, weakness of muscles, and inability to stand up, all caused by sudden loss of blood flow to the brain. Fainting is a relatively common symptom caused by a variety of problems relating to changes in blood pressure. The American Heart Association reports that fainting is responsible for 3% of all visits to emergency rooms and 6% of all admissions to hospitals.


Fainting is a common symptom, also called syncope, vasovagal attack, neurally mediated syncope (NMS), neurocardiogenic syncope, and vasodepressor or reflex mediated syncope. Most simple faints result from an overstimulation of the autonomic nervous system that results in a drop in blood pressure and a slowed heart rate. Both of these conditions decrease blood flow to the brain, which causes a feeling of lightheadedness (presyncope) or a complete loss of consciousness (syncope). Fainting usually occurs in people who are standing or sitting upright. A person about to faint may also feel nauseated, weak, and warm. The person may experience temporary visual impairment, headache , ringing in the ears, shortness of breath, sensation of spinning, tingling in the extremities, and incontinence. A person experiencing presyncope may also appear pale or bluish. When consciousness is lost, a person usually falls down. This allows for more blood flow to the brain, resulting in a return to consciousness, usually within a few minutes.


Fainting is caused by a variety of factors, including stress, pain , overheating, dehydration, excessive sweating, exhaustion, hunger, alcohol, and drugs. Fainting may also be a side effect of some medications. A simple faint resulting from any of these factors is usually not a symptom of a neurological disorder.

Some people faint when changing positions, a condition known as postural hypotension. When people with this condition move from a lying position to a standing or sitting position, the sudden pooling of blood in the legs may cause a temporary decrease in blood circulation to the brain, causing a faint. This condition is common in elderly people who have been bedridden for some time and in people with poor muscle tone.

Some faints indicate serious disorders of the nervous or circulatory systems. Nervous system disorders that cause faints include acute or subacute dysautonomia, post-ganglionic autonomic insufficiency, and chronic preganglionic autonomic insufficiency. Fainting may also signal an irregular pattern of nervous stimulation such as micturition syncope (fainting while urinating), glossopharyngeal neuralgia (irritation of the ninth cranial nerve, causing pain in the tongue, throat, ear, and tonsils), cough syncope (fainting while coughing violently), and stretch syncope (fainting when stretching arms and neck). Faints can also indicate problems with the regulation of blood pressure and heart rate, and with disorders such as diabetes, alcoholism, malnutrition, and amyloidosis. Fainting can signal circulatory problems, particularly those that disrupt blood flow to the brain, as well as problems with the electrical impulses that control the heart, problems with the sinus node of the heart, heart arrhythmia, blood clots in the lung, a narrowing of the aorta, or other anatomical irregularities in the heart. Additionally, hyperventilation, usually associated with anxiety or panic, can result in a faint.


Patients visiting a doctor because of fainting will usually have their blood pressure checked when they are lying down and then again after they stand up. If there is a significant decrease in blood pressure, it may indicate postural hypotension. A more sophisticated form of this blood pressure test is a tilt test, during which a person is strapped to a board that is rotated from the horizontal to the vertical position. Blood pressure is measured in both positions; an extreme drop indicates postural hypotension.

To test for circulatory problems, a physician may also use an electrocardiogram (EKG) to test for abnormalities of the heart beat. Exercise stress tests or wearing a Holter monitor for a day may also be performed to check for disorders of the heart. Fainting suspected to be caused by neurological disorders requires additional tests and evaluation by a neurologist .


If a person faints while sitting, the body weight should be supported and the head positioned between the knees. If a person faints while standing, the individual should be carefully lowered to the ground and the legs elevated. Any tight clothes, including belts and collars, should be loosened. The head should be turned to the side so that the tongue does not obstruct the trachea and any vomit can be cleared from the airway. If the person stops breathing, cardiopulmonary resuscitation (CPR) should be started and a call should be placed to emergency medical services. A person who has fainted may benefit from cold compresses to the head and neck. After the person regains consciousness, he or she should remain lying or sitting for some time and should stand up only if no feeling of light-headedness persists.

A person who faints often will be treated for the underlying condition. Often, medications are used to control fainting; however, other methods may be helpful as well. In some people, changing to a high-salt diet or wearing support hose to keep blood from pooling in the legs prevents fainting. Some people may be able to prevent fainting by keeping glucose levels at a more constant level or by learning breathing techniques to prevent hyperventilation. Another technique for preventing faints is drinking enough fluid to keep blood volume high.



Icon Health Publications. The Official Patient's Sourcebook on Syncope: A Revised and Updated Directory for the Internet Age. San Diego, CA: ICON Group International, 2003.


DeNoon, Daniel. Fainting Is a Serious Symptom. WebMD. January 14, 2002 (March 18, 2004). <http://my.webmd.com/content/Article/35/1728_96070.htm>.

Fainting. FamilyDoctor. March, 2002 (March 18, 2004). <http://familydoctor.org/x1682.xml?printxml>.

Grayson, Charlotte. Understanding FaintingThe Basics. WebMD. January 1, 2002 (March 18, 2004). <http://mywebmd.com/content/article/7/2951_478>.

The Mayo Clinic Staff. Simple Faint (Vasovagal Syncope). The Mayo Clinic. June 26, 2003 (March 18, 2004). <http://www.mayoclinic.com/invoke.cfm?id=AN00103>.

Syncope. American Heart Association. December 22, 2003 (March 18, 2004). <http://www.americanheart.org/presenter.jhtml?identifier=4749>.


American Heart Association National Center. 7272 Greenville Avenue, Dallas, TX 75231. (800) AHA-USA1. <http://www.americanheart.org/presenter.jhtml?identifier=1200000>.

National Heart, Blood and Lung Institute. P.O. Box 30105, Bethesda, MD 20824-0105. (301) 592-8573; Fax: (301) 592-8563. <http://www.nhlbi.nih.gov/index.htm>.

National Institute of Neurological Disorders and Stroke. P.O. Box 5801, Bethesda, MD 20824. (301) 496-5751 or (800) 352-9424. <http://www.ninds.nih.gov/>.

Juli M. Berwald

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Fainting (Syncope)

The Attorney General Passes Out

What Is Fainting?

What Causes Fainting?

What Happens When People Faint?


Fainting is a brief loss of consciousness caused by a temporary drop in blood flow to the brain.


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Circulatory system

Blood pressure

The Attorney General Passes Out

One minute, U.S. Attorney General Janet Reno was sitting in church. The next minute, she was peering up at a circle of concerned faces. Sixty-year-old Reno had just had a fainting spell, her second in less than a year. The September 1998 incident made the news because of Renos famous name, but fainting is common. The cause of Renos spell was unknown, but doctors said it might have been due to her heavy work load or the tremendous job stress that comes with being the chief law officer of the United States.

What Is Fainting?

Fainting, also known as syncope (SING-ko-pee), is a brief loss of consciousness caused by a temporary drop in blood flow to the brain. Blood carries

Blacking Out in Blue Skies

In World War II, fighter pilots sometimes lost their lives because of fainting.

During high-speed flight, very rapid changes in speed create a force that is expressed as a unit of gravity (g). A force of 4 to 6 g makes blood become very heavy and pool in the lower part of the body, robbing the brain of its blood supply. Many high-speed moves create a force this great. For example, pulling out of a dive can produce a force up to 9 g. When this happened, pilots fainted and crashed.

It was up to scientist Wilbur R. Franks to find a solution to this problem. In 1942, Franks invented the first anti-gravity suit. This is a flight suit with special pants that apply pressure to the legs and belly, forcing blood back into the upper part of the body. Frankss invention gave Allied pilots a competitive edge during the war. The suits worn by jet pilots and astronauts today are still based on his design.

oxygen to the brain. Without enough oxygen, brain processes slow down, and the person may pass out briefly. There can be several reasons for the sudden drop in blood flow, including an irregular heart rate or rhythm, a dip in blood pressure, or the pooling of blood in the legs usually after a prolonged period of standing. Although fainting can be scary and embarrassing, it usually is not a cause for panic. Healthy people sometimes faint when they are extremely tired, get bad news, or see something upsetting. In other cases, however, fainting may be a sign of a more serious medical condition.

What Causes Fainting?

One in three people faints at some point in life. The problem occurs in people of all ages, although it is most common in people over age 65. There are many possible causes. These are some of the more frequent ones:

Heart disorders

The most serious causes of fainting usually involve the heart or blood vessels. In some cases, the heart beats too fast or with an irregular rhythm, reducing the amount of blood it pumps. In other cases, there is a narrowing of the valve that lets blood out of the heart or a partial blockage of the blood vessels that carry blood to the head, limiting blood flow to the brain.

Emotional Stress

Stress, fright, or sudden pain can arouse the nervous system, which, in turn, can signal the heart to slow down or the blood vessels to widen. If such changes happen too quickly, a persons blood pressure can drop suddenly. This reduces blood flow to the brain, and the person may faint.

Heavy sweating

Sweat contains sodium, a mineral that plays a key role in blood pressure control. Heavy sweating is another possible cause of a sudden dip in blood pressure. This often is a problem for people who take part in strenuous physical activities under hot, humid conditions.

Dancing Mania and Mass Fainting

The phenomenon of mass fainting was reported to have occurred in the Middle Ages as a result of what was known as dancing mania.

Dancing mania reportedly was induced by minstrels who played intoxicating music at medieval festivals. The music stimulated fits of wild dancing, leaping, hopping, and clapping that led to hyperventilation, heart palpitations, and other symptoms.

Dancing mania curiously parallels the fainting that sometimes occurs at present day rock concerts.

Standing up quickly

When most people stand up, the nervous system triggers a reflex response that increases the heart rate and blood pressure. This insures that enough blood gets to the brain. In some people, particularly the elderly, these responses may not occur fast enough. Blood may pool in the legs. When too little blood reaches the brain, the person may faint.

What Happens When People Faint?


Some people simply lose consciousness and slump down without warning. However, many people feel dizzy, lightheaded, or sick to their stomach just before they faint. They may become sweaty and pale, and they may have a graying out of vision. By definition, a faint does not last long. Falling down places the head at the same level as the heart. This helps restore blood flow to the brain. The person soon regains consciousness, usually within a minute or so.


A person feeling faint should lie down immediately and not try to stand or walk. If the person who faints dos not regain consciousness within a minute or two, it is important to get emergency medical help immediately. While awaiting emergency help, adult bystanders probably will elevate the legs of the person who has fainted; loosen belts, collars, or tight clothing; and check that the persons airway remains open, as people who faint may vomit as well. They will not move the person who has fainted until medical help arrives because a fall may have injured the person.

The person who has fainted probably will regain consciousness quickly, but may continue to feel a bit weak for a little while. To keep from fainting again, the person should stay lying quietly for a few minutes.

Even when people recover promptly, they should contact their doctors about a first fainting attack, about repeated fainting spells, or about other possible symptoms including irregular heartbeat, chest pain, shortness of breath, blurred vision, confusion, or trouble talking.

See also

Altitude Sickness

Heart Disease



American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231, (800) AHA-USA1. This group has information about syncope on its website, http://www.americanheart.org

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fainting is a transient, reversible loss of consciousness due to an acute reduction in blood supply to the brain. Lack of cerebral perfusion for 2–3 sec can cause premonitory symptoms (such as light-headedness, dizziness); after 10 sec fainting results. Fainting is synonymous with syncope (from the Greek ‘to strike’ or ‘cut off’). Slumping in a chair or falling to the ground characteristically occurs because of loss of postural muscle tone, although occasionally there may be jerky movements, muscle spasms, or urinary incontinence as a result of transient ‘decerebration’. Fainting usually occurs when the subject is upright, and falling results in recovery of cerebral blood flow and spontaneous recovery.

Fainting does not cause damage to the nervous system, unless there is injury from the fall, but it can cause concern, embarrassment, and loss of confidence. However some of the conditions associated with fainting are potentially serious or even potentially fatal. It has been said that ‘the only difference between fainting and sudden death is that in one you wake up’ (Engel, 1978).

Maintenance of blood flow to the brain is dependent on an adequate blood pressure and on patent and responsive cerebral blood vessels. These vessels dilate to maintain flow when blood pressure falls within its normal range of variation, but a major or rapid fall can defeat this compensation. Thus, there are numerous causes of fainting.

Low blood pressure (hypotension) may occur with postural (orthostatic) change, on moving from the horizontal to the upright position such as when rising after sleep. The sympathetic nervous system normally responds to gravitational change and prevents pooling of blood in the lower limbs by an increase in its activity, which causes constriction of blood vessels. The majority of the population do not faint, as adaptive mechanisms to standing erect are well developed. However, in certain situations even the fittest can faint (such as guardsmen standing still at attention on a hot day), and there are some disease conditions, and some drugs, which impair the reflex response. Fainting caused by postural hypotension classically occurs on assumption of the head-up posture, with relief by lying flat.

Intermittent abnormal activity of the autonomic nervous system (neurally-mediated syncope) also may occur. During these episodes increased parasympathetic activity slows the heart rate whilst diminished sympathetic activity allows blood vessels to dilate, lowering blood pressure. The most common form is known as vasovagal syncope — the ‘emotional’ or ‘common’ fainting. This is often of teenage onset, in females, and with a family history.

A variety of factors, such as fear of needles, sight of blood, or pain, can precipitate this type of fainting. There is often prompt recovery on attaining the horizontal position. In the elderly, similar autonomic effects on the heart and circulation may occur, when there is hypersensitivity of the baroreceptors in the carotid sinus in the neck; tightening the collar, or moving the head whilst shaving, stimulates nerves that normally signal a rise in blood pressure. The result is a ‘correction’ of this false signal — a fall in heart rate and blood pressure. This can be a potentially serious condition, with severe injury from falls, and may require treatment with a cardiac pacemaker and drugs that maintain blood pressure.

There are other, rarer, causes of fainting mediated by the nervous system, precipitated by a range of factors such as urination, coughing, or swallowing.

Another cause of fainting is a change in cardiac rhythm, when the heart beats too fast or too slowly, resulting in a poor cardiac output and inadequate blood flow to the brain. The best known is the Stokes–Adams attack, when the ventricles of the heart fail to beat because of heart block.

There are also more direct — mechanical or hydraulic — causes of low blood pressure; these include depletion of the circulating blood volume due to haemorrhage or plasma loss, and inadequate fluid intake or excessive fluid loss due to vomiting or diarrhoea, or from the kidneys in some abnormal conditions. Excessive dilatation of blood vessels, due to drugs (such as glyceryl trinitrate used in angina, or from excessive alcohol ingestion), circulating vasodilator substances, or venous disorders (extensive varicose veins), may be contributory.

Finally, constriction of the cerebral blood vessels may contribute to fainting. For example, during hyperventilation, even in healthy people, low carbon dioxide in the blood causes constriction of the blood vessels. Or when a major vessel supplying the brain is partly or severely occluded in carotid artery stenosis, even small decreases in blood pressure or changes in cardiac rhythm threaten the blood supply.

In summary, fainting may occur in any individual, from the young (vasovagal syncope), to the elderly (carotid sinus hypersensitivity). It is estimated to occur at some time in 3% of the adult population, and sometimes in extremely healthy and fit people (oarsmen, athletes, and in particular weightlifters). There may be an occupational hazard — as in trumpet players. Fainting is usually involuntary, but it may be deliberately induced, as in the so-called ‘fainting lark’: a combination of squatting, overbreathing, forceful expiration, and standing up suddenly. The ‘Mess trick’ is a variation of this.

Fainting can sometimes be ominous, especially in those with an untreated cardiac rhythm disorder, consistent with ancient observations that ‘those who suffer from frequent and severe fainting without cause often die suddenly’ ( Hippocrates, Aphorisms 2.41). But in many other conditions, such as vasovagal syncope, the prognosis is excellent.

C. J. Mathias

See also autonomic nervous system; blood pressure.
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fainting or syncope (sĬng´kəpē), temporary loss of consciousness caused by an insufficient supply of oxygen to the brain. It can be concurrent with any serious disease or condition, such as heart failure, hypertension (high blood pressure), arrhythmia, hemorrhage, injury to the brain or other organs, or poisoning. Less serious conditions can also cause fainting, e.g., fatigue, prolonged standing, getting up after long confinement to bed, pain, hunger, dehydration, anemia, or fright or other emotional disturbance. Loss of control of blood pressure can be detected with the tilt test. Such drugs as scopolamine, beta-blockers, and disopyrmide have been successful in restoring the integrity of the vascular system. Person aware of an oncoming fainting spell should sit down and lower their heads between their knees for a moment or two to increase the flow of oxygen to the brain. The already unconscious person should be placed in a supine position, preferably with the feet raised. If unconsciousness persists, cold water on the face or the inhalation of aromatic spirits of ammonia may be tried. Under no circumstances should any liquid or medication be forced down the throat of an unconscious person. Fainting for more than a few minutes requires medical attention. After regaining consciousness, the patient should remain recumbent for at least 10 minutes and arise gradually.

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fainting (syncope) Temporary loss of consciousness accompanied by general weakness of the muscles. A faint may be preceded by giddiness, nausea and sweating. Its causes include insufficient flow of blood to the brain and shock.

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fainting (faynt-ing) n. see syncope.