Facts on Fainting
- Fainting, which medical professionals call syncope (pronounced SIN-ko-pea), is a temporary loss of consciousness. Fainting is caused by a temporary loss of the brain's blood supply and can be a sign of a more serious condition.
- People of any age can faint, but elderly persons may have a serious underlying cause.
Fainting (syncope) has many different causes.
Vasovagal syncope: Also known as the "common faint," this is the most frequent cause of syncope. It results from an abnormal circulatory reflex. The heart pumps more forcefully and the blood vessels relax, but the heart rate does not compensate fast enough to maintain blood flow to the brain. People older than 45 years of age rarely experience a first "common faint." Causes of vasovagal syncope include the following:
- Environmental factors: Most commonly in a hot, crowded setting
- Emotional factors: Stress or the sight or threat of injury
- Physical factors: Standing too long
- Illness: Fatigue, dehydration, or other illnesses
Situational syncope: This is a type of vasovagal syncope that only occurs in particular situations. Causes of situational syncope include the following:
- Cough syncope occurs in some people when coughing forcefully.
- Swallow syncope occurs upon swallowing in some people with disease in the throat or esophagus.
- Micturition syncope occurs when a susceptible person empties an overfilled bladder.
- Carotid sinus hypersensitivity occurs in some people when turning the neck, shaving, or wearing a tight collar.
- Postprandial fainting can occur in elderly people when their blood pressure falls about an hour after eating.
Postural syncope: This occurs when a person lying down, who feels perfectly well and alert, suddenly faints upon suddenly standing up. The brain's blood flow decreases when the person stands due to a temporary drop in blood pressure. This sometimes occurs in people who have recently started or changed certain cardiovascular medications. This type of fainting results from either or both of the following causes:
- Low circulating blood volume, caused by blood loss (external or internal), dehydration, or heat exhaustion
- Impaired circulatory reflexes, caused by many medications, disorders of the nervous system, diabetes, or congenital problems
Cardiac syncope: Heart disease causes a person to faint by a variety of mechanisms. Cardiac causes of fainting are generally life-threatening and include the following:
- Cardiac rhythm abnormality (arrhythmia): Electrical problems of the heart impair its pumping ability. This causes a decrease in blood flow. The heart rate may be either too fast or too slow to pump blood well. This condition usually causes fainting without any warning symptoms.
- Cardiac obstruction: Blood flow can be obstructed within the blood vessels in the chest. Cardiac obstruction can cause fainting during physical exertion. A variety of diseases cause obstruction, including heart attacks, diseased heart valves, pulmonary embolism, cardiomyopathy, pulmonary hypertension, cardiac tamponade, and aortic dissection.
- Heart failure: The heart's pumping ability is impaired. This lowers the force with which blood circulates through the body and may decrease blood flow in the brain.
Neurologic syncope: This syncope can be due to a neurologic condition or event listed below.
- Stroke (bleeding in the brain) can cause syncope associated with headache.
- Transient ischemic attack (TIA or mini-stroke) can cause fainting, usually preceded by double vision, loss of balance, slurred speech, or vertigo (a spinning sensation).
- Migraines can cause fainting on rare occasions.
Psychogenic syncope: Hyperventilation from an anxiety disorder can cause fainting. Rarely, people pretend to faint to minimize stress or for some recognized gain. The diagnosis of psychogenic syncope should only be considered after all other causes have been excluded.
Unconsciousness is an obvious sign of fainting.
- Before fainting, the person may feel light-headed and shaky and experience blurred vision.
- The person may "see spots in front of their eyes."
- During this time, observers note paleness, dilated pupils, and sweating.
- While unconscious, the person may have low pulse rate (less than 60 beats/minute).
- The person should quickly regain consciousness.
- Many people have no warning signs before a fainting (syncopal) episode.
- Consciousness returns when the situation is over, usually very quickly.
- Prior to the fainting episode, the person may have noted a blood loss (black stools, heavy menstrual periods) or fluid loss (vomiting, diarrhea, fever).
- The person may have experienced light-headedness when sitting or standing.
- Observers may note paleness, sweating, or signs of dehydration (dry lips and tongue).
- The person may report palpitations (awareness of pounding, fast, or abnormal heartbeat), chest pain, or shortness of breath.
- Observers may note a weak, abnormal pulse, paleness, or sweating.
- Fainting often occurs without warning or following exertion.
When to Seek Medical Care
Because fainting can be caused by a serious condition, all episodes of fainting should be taken seriously. Anyone who has a first episode of fainting needs to be evaluated by a health care practitioner as soon as possible. If the patient has a history of fainting and a specific diagnosis explaining the syncopal episodes, they should still make the health care practitioner aware that he or she had another episode of fainting. The health care practitioner can decide if the patient needs to be evaluated. Although most people with a history of vasovagal, situational, or postural causes of fainting do not require hospitalization, many doctors prefer to have anyone that faints or has a "short loss of consciousness" be examined by a health care professional.
- Most diagnoses are made through a thorough medical history and physical examination along with an electrocardiogram, or ECG (heart tracing). Based on the findings during the medical history and physical exam, further tests might be ordered to find the underlying cause of the syncopal episode. As part of the medical history, it is important to document whether or not the patient hit his or her head during the fall. A closed head injury can complicate the evaluation and treatment of an episode of fainting.
Cardiac syncope: If a cardiac cause is suspected, several tests are available. Most are used to identify coronary heart disease, heart valve problems, heart failure, or arrhythmias. In addition to the EKG, an echocardiogram of the heart will often be part of the evaluation.
Noncardiac syncope: Testing depends on the suspected cause. A CT scan is rarely useful but might be ordered. Head-up tilt testing is useful to diagnose vasovagal syncope.
Fainting Self-Care at Home
- If possible, help the person who has fainted to the ground to minimize injury.
- Stimulate the person vigorously (yelling, briskly tapping). Call 911 immediately if the person does not respond.
- Check for a pulse and begin CPR, if needed.
- After the person recovers, encourage him or her to lie down until medical help arrives. Even if you believe the cause of the fainting is harmless, have the person lie down for 15-20 minutes before attempting to get up again.
- Ask about any persistent symptoms, such as headache, back pain, chest pain, shortness of breath, abdominal pain, weakness, or loss of function, because these may indicate a life-threatening cause of the fainting.
The treatment of fainting depends on the diagnosis.
- Lifestyle alterations: Drink plenty of water, increase salt intake (under medical supervision), and avoid prolonged standing.
- Lifestyle alterations: Sit up and flex calf muscles for a few minutes before getting out of bed. Avoid dehydration. Elderly people with low blood pressure after eating should avoid large meals or plan to lie down for a few hours after eating.
- Medications: In most cases, medications that cause fainting are withdrawn or changed.
The treatment for cardiac syncope is very specific to the underlying illness. Valvular heart disease often requires surgery, while an arrhythmia might require medications or other treatments listed below.
- Medication and lifestyle alterations: These treatments are designed to optimize the heart's performance while limiting its demands. Controlling high blood pressure, for example, would involve medication and lifestyle changes. In some cases, specific anti-arrhythmic medication may be prescribed.
- Surgery: Bypass surgery or angioplasty is used to treat coronary heart disease. For some valve problems, valves can be replaced. Catheter ablation is available to treat some arrhythmias.
- Pacemaker: A pacemaker may be implanted to correct the heart rate, slowing the heart in certain types of fast arrhythmias or speeding up the heart for slow arrhythmias.
- Implanted defibrillators are used to control life-threatening fast arrhythmias.
- If the cause of fainting or syncope is not determined, and the affected person is not hospitalized, he or she should see a health care practitioner within a few days. Learn to check your own pulse and teach your family members what to do in case you faint again.
- Many people never faint again after the first time.
- The affected individual may be referred to a heart specialist if cardiac syncope is suspected.
- If neurologic disease is suspected during the emergency department evaluation, the person should be referred to a neurologist.
Preventive measures depend on the cause and the severity of the fainting problem. Fainting can sometimes be prevented by taking simple precautions.
- If you faint in hot rooms, the solution is obvious: Avoid hot rooms.
- If you faint while standing up from a lying down position, take care to move slowly when standing up. Move slowly to a sitting position and rest a few minutes. When you are ready, stand up, using slow and fluid movements.
In other cases, the cause of fainting can be elusive. Several visits to your health care practitioner may be needed to establish a pattern of when fainting occurs and thus lead to a diagnosis. Once the cause is determined, treatment can be started to prevent further episodes.
Cardiac syncope: Because of the high risk of death from cardiac syncope, people who experience it and their family members must understand the disease and its treatment (especially controlling the condition through diet and medications).
- Follow the recommendations of your health care practitioner precisely.
- Take prescribed medications regularly.
Recurrent syncope: See your health care practitioner about testing to establish a diagnosis if you faint periodically. Ask your health care practitioner about driving. Many states have laws applying to people who have a history of losing consciousness.
The prognosis of a person who has fainted depends greatly on the underlying cause, age of patient and available treatments. Cardiac syncope carries the highest chance of sudden death especially in the elderly. Fainting that is not associated with cardiac or neurologic disease, however, presents a more limited risk although it is higher than in the general population.
Medically reviewed by John A. Daller, MD; American Board of Surgery with subspecialty certification in surgical critical care