Vasovagal Syncope: Symptoms, Diagnosis, Treatments

Vasovagal Syncope: A Common Cause of Fainting

Vasovagal Syncope: Symptoms, Diagnosis, Treatments

Syncope—also known as fainting—is the medical term for a temporary loss of consciousness. Any episode of syncope is important for at least two reasons.

First, syncope can cause injury, so it is important to try to prevent it from recurring. And second, syncope can sometimes be a sign of a serious underlying medical problem.

While several medical conditions can lead to syncope, by far the most common type of syncope is vasovagal syncope.

Verywell / Brooke Pelczynski

Vasovagal syncope (also called neurocardiogenic syncope) is a temporary loss of consciousness caused by a neurological reflex that produces either sudden dilation of the blood vessels in the legs, or a very slow heart rate (bradycardia), or both.

Vasovagal syncope accounts for more than half of all episodes of syncope. While doctors often refer to it as a “simple fainting spell,” the mechanism of vasovagal syncope actually is not all that simple. And misunderstanding how vasovagal syncope works can lead to problems in making the correct diagnosis or in choosing adequate treatment.

Vasovagal syncope occurs when something triggers the vasovagal reflex, causing the blood vessels to suddenly dilate. Dilation of the blood vessels causes a significant proportion of the blood volume to pool in the legs.

This pooling is often accompanied by a slowing of the heart rate. As a result, the blood pressure will suddenly drop. If the drop in pressure is enough to rob the brain of oxygen, fainting occurs.

In most people with vasovagal syncope, the dilation of blood vessels appears to be the predominant factor that causes loss of consciousness. In some people, however, the slowing of the heart rate plays a major role.

Common triggers of vasovagal syncope include:

  • Sudden, severe pain
  • Having your blood drawn
  • Being exposed to a traumatic sight or event
  • Extremely difficult urination or defecation
  • A severe coughing spell
  • Hyperventilation
  • Standing motionless for long periods of time
  • Overexerting yourself in hot weather
  • Excessive alcohol or substance use

If a fainting episode follows any of these events, vasovagal syncope is almost certainly the cause.

While the loss of consciousness with vasovagal syncope can be quite sudden, more characteristically it is preceded by a few seconds or a few minutes of warning symptoms. These symptoms are sometimes referred to as a “prodrome” of syncope. Those that occur after you are revived are called “postdromal.”

These prodromal symptoms of syncope often include:

  • Lightheadedness
  • Ringing or buzzing in the ears
  • Visual disturbances, such as shimmering vision or tunnel vision
  • Sudden sweating.
  • Sudden nausea

These prodromal symptoms are followed by a sensation of “graying out,” then finally by loss of consciousness. The time between the onset of prodromal symptoms and actually passing out may be a few minutes, or just a second or two.

If you feel you’re going to faint, you may be able to abort the episode by lying down with your legs elevated or sitting in a chair with your head between your knees. Wait until you feel better before trying to stand.

The syncope itself also has several characteristic features: 

  • Vasovagal syncope almost always occurs when the victim is standing, or sitting upright (when blood pooling in the legs can occur), and it virtually never happens while lying down.
  • People who have vasovagal syncope usually regain consciousness after a few seconds, once they have fallen (or, if they're lucky, are helped) to the ground. This is because once on the ground, gravity no longer causes the blood to pool in the legs and the blood pressure improves almost immediately.
  • On the other hand, if the victim is held upright by a well-meaning bystander, the unconsciousness can become very prolonged. This is a potentially dangerous situation because as long as the victim is upright and unconscious, his or her brain is not being adequately perfused with blood.

If you see somebody faint, lay that person on his or her back and elevate the legs about 12 inches above the heart. Loosen any belt, collar, or constrictive clothing. Seek help if the fainting lasts for longer than a few seconds.

After an episode of vasovagal syncope, many people will feel terrible for a few hours or even for the next few days, or even longer. During this “postdromal” period they commonly experience extreme fatigue, nausea, dizziness, and loss of appetite. 

It is particularly important to note that, until these lingering (and very annoying) symptoms disappear, people are particularly prone to fainting again—so they need to be particularly alert for the warning symptoms that may indicate that an episode of syncope is imminent. 

People who have had one or two episodes of vasovagal syncope are frequently able to recognize the warning symptoms, so they will know when another event is about to occur. More importantly, if they do recognize the warning symptoms, they can prevent the blackout simply by lying down and elevating their legs.

On the other hand, trying to “fight off” an impending episode of vasovagal syncope by forcing yourself to remain upright and willing yourself not to faint almost never works out very well.

Older people with vasovagal syncope are more ly to have “atypical” symptoms. Their syncope may occur without any identifiable trigger, and without any warning symptoms. Making the correct diagnosis in these cases can present a real challenge to the doctor.

In general, vasovagal syncope is not itself life-threatening, but injuries that result from falling may be. And if episodes are frequent enough this condition can certainly be quite disruptive to a normal life.

A single fainting episode is not usually serious. However, you should see a doctor if you are pregnant, have recurrent episodes, or experience blurred vision, chest pain, confusion, trouble talking, shortness of breath, or irregular heartbeat prior to fainting.

The reflex that causes vasovagal syncope can occur to some extent in everyone, so almost anyone can have a vasovagal episode if a sufficiently strong triggering event occurs. Indeed, it is ly that most people will have a fainting episode sometime during their lives.

Vasovagal syncope can occur at any age, but it is much more common in adolescents and young adults than in older people.

Some people are particularly prone to vasovagal episodes and may faint even with relatively mild triggering events. These people tend to have recurrent episodes of syncope, beginning in adolescence. They will often experience syncope following several different kinds of triggering events.

In rare individuals, vasovagal syncope is so frequent and so difficult to treat that they become virtually disabled by it.

These people often have a form of dysautonomia (imbalance of the autonomic nervous system) that makes them very prone to the vasovagal reflex that causes this condition.

They often have other symptoms typical of the dysautonomias, such as abdominal bloating or cramps, diarrhea, constipation, extreme fatigue, and various aches and pains.

Doctors who are skilled at correctly diagnosing vasovagal syncope understand that this condition is almost always situational. Vasovagal syncope is particularly ly to occur after a viral illness, after exercise, after a warm shower, or early in the morning—in other words, any time relative dehydration is ly to be present.

Given these characteristic features and the situational nature of this condition, doctors should be able to make the correct diagnosis by simply reviewing the symptoms, medical history, family history, and sequence of events leading up to the fainting.

While in most cases making the diagnosis of vasovagal syncope ought to be possible by taking a medical history and doing a physical examination, testing is sometimes helpful. In particular, a tilt table study can be helpful if the medical history is not typical for vasovagal syncope, or if it is difficult to distinguish between vasovagal syncope and orthostatic hypotension.

People who have a single, isolated episode of vasovagal syncope generally do not require any medical therapy at all.

But if you have had recurrent episodes, you are ly to have even more episodes unless you are effectively treated. And, as anyone with vasovagal syncope knows, these fainting episodes often come at the most inconvenient or impractical times, and can greatly disrupt your life. Fortunately, treatment is usually quite helpful.

There are four general types of therapy for vasovagal syncope: medication, exercise, and pacemakers.

In some people, vasovagal syncope occurs with disturbing frequency even when all appropriate precautions are taken. For these individuals, drug therapy is often helpful.

In the past, the drugs were most commonly used for vasovagal syncope were the beta blockers, but several studies have failed to show any benefit and these drugs are currently not recommended.

Drugs that have been shown to be of some help include:

  • Midodrine, a vasoconstricting drug that dilates blood vessels
  • Norpace (disopyramide), an antiarrhythmic drug 
  • Serotonin re-uptake inhibitors 
  • Theophylline, typically used to treat asthma

While one or more of these drugs will often help reduce episodes of syncope, finding the “right” combination of drugs is usually a matter of trial and error. Patience is required on the part of both the doctor and patient in order to find the best therapy.

Many people who have dysautonomia also display a tendency to have vasovagal syncope; indeed, it seems ly that many people with recent vasovagal syncope may actually have a form of dysautonomia. Since some dysautonomias respond favorably to exercise, exercise may ly have a similar benefit to people with vasovagal syncope.

If you have recurrent syncope, be sure to meet with your doctor before embarking on any fitness plan. Depending on the underlying cause, you may need to undergo stress testing and other exams to determine how much exercise you can tolerate.

Interestingly, some people have been able to abort an episode of vasovagal syncope by immediately engaging in muscle-tensing exercises. These exercises apparently reduce blood vessel dilation and increase the amount of blood being returned to the heart. Examples include

  • Crossing your leg while tensing the legs, abdomen, and buttocks
  • Tensing the arms with clenched fists
  • Tensing your leg muscles
  • Squeezing a rubber ball

Several years ago there was a lot of enthusiasm for using pacemakers to treat vasovagal syncope since vasovagal syncope is usually accompanied by a sudden drop in heart rate.

The enthusiasm for pacemaker therapy dropped off rapidly, however, after it was finally noted that many patients with vasovagal syncope who received pacemakers continued to pass out—they just did it without slow heart rates.

As it turns out, it is the pooling of blood in the legs—and not a slow heart rate—that produces syncope in most people. Still, in some, the drop in heart rate may the predominant cause.

A pacemaker should only be explored if the syncope is severe or recurrent, conservative measures have failed, and there is significant slowing of the heart as evidenced by a tilt-table test or ambulatory ECG monitoring.

Vasovagal syncope is a very common condition. Fortunately, it usually occurs in rare, isolated episodes or during a limited period of time. Most people who have vasovagal syncope lead entirely normal lives.

If you have had vasovagal syncope—especially more than one episode—you should learn as much as you can about this condition, including what kinds of things provoke it, how to recognize the warning symptoms and how you might stop an episode.

If you have repeated episodes of syncope despite taking such steps, you should talk to your doctor about whether something more than mere “avoidance therapy” is needed.


Diagnosis and treatment of syncope

Vasovagal Syncope: Symptoms, Diagnosis, Treatments

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Syncope: Symptoms, Causes, Treatments

Vasovagal Syncope: Symptoms, Diagnosis, Treatments

Syncope (pronounced “sin ko pea”) is the medical term for fainting or passing out. It is caused by a temporary drop in the amount of blood that flows to the brain.

Syncope can happen if you have a sudden drop in blood pressure, a drop in heart rate, or changes in the amount of blood in areas of your body. If you pass out, you will ly become conscious and alert right away, but you may be feel confused for a bit.

Autonomic Nervous System (ANS)

The ANS automatically controls many functions of the body, such as breathing, blood pressure, heart rate and bladder control. Most times, these things happen without us noticing.

How common is syncope?

Syncope is a common condition. It affects 3% of men and 3.5% of women at some point in life. Syncope is more common as you get older and affects up to 6% of people over age 75. The condition can occur at any age and happens in people with and without other medical problems.

Types of Syncope

There are several different types of syncope. The type you have depends on what causes the problem.

Vasovagal syncope (also called cardio-neurogenic syncope)

Vasovagal syncope is the most common type of syncope. It is caused by a sudden drop in blood pressure, which causes a drop in blood flow to the brain. When you stand up, gravity causes blood to settle in the lower part of your body, below your diaphragm. When that happens, the heart and autonomic nervous system (ANS) work to keep your blood pressure stable.

Some patients with vasovagal syncope have a condition called orthostatic hypotension. This condition keeps the blood vessels from getting smaller (as they should) when the patient stands. This causes blood to collect in the legs and leads to a quick drop in blood pressure.

Situational syncope

Situational syncope is a type of vasovagal syncope. It happens only during certain situations that affect the nervous system and lead to syncope. Some of these situations are:

  • Dehydration
  • Intense emotional stress
  • Anxiety
  • Fear
  • Pain
  • Hunger
  • Use of alcohol or drugs
  • Hyperventilation (breathing in too much oxygen and getting rid of too much carbon dioxide too quickly)
  • Coughing forcefully, turning the neck, or wearing a tight collar (carotid sinus hypersensitivity)
  • Urinating (miturition syncope)

Postural syncope (also called postural hypotension)

Postural syncope is caused by a sudden drop in blood pressure due to a quick change in position, such as from lying down to standing. Certain medications and dehydration can lead to this condition.

Patients with this type of syncope usually have changes in their blood pressure that cause it to drop by at least 20 mmHg (systolic/top number) and at least 10 mmHg (diastolic/bottom number) when they stand.

Cardiac syncope is caused by a heart or blood vessel condition that affects blood flow to the brain.

These conditions can include an abnormal heart rhythm (arrhythmia), obstructed blood flow in the heart due to structural heart disease (the way the heart is formed), blockage in the cardiac blood vessels (myocardial ischemia), valve disease, aortic stenosis, blood clot, or heart failure. If you have cardiac syncope, it is important to see a cardiologist for proper treatment.

Neurologic syncope

Neurologic syncope is caused by a neurological condition such as seizure, stroke or transient ischemic attack (TIA). Other less common conditions that lead to neurologic syncope include migraines and normal pressure hydrocephalus

Postural Orthostatic Tachycardia Syndrome (POTS)

Postural-Orthostatic Tachycardia Syndrome is caused by a very fast heart rate (tachycardia) that happens when a person stands after sitting or lying down. The heart rate can speed up by 30 beats per minute or more. The increase usually happens within 10 minutes of standing. The condition is most common in women, but it can also occur in men.

Unknown Causes of Syncope

The cause of syncope is unknown In about one-third of patients. However, an increased risk of syncope is a side effect for some medications.

What are the symptoms of syncope?

The most common symptoms of syncope include:

  • Blacking out
  • Feeling lightheaded
  • Falling for no reason
  • Feeling dizzy
  • Feeling drowsy or groggy
  • Fainting, especially after eating or exercising
  • Feeling unsteady or weak when standing
  • Changes in vision, such as seeing spots or having tunnel vision
  • Headaches

Many times, patients feel an episode of syncope coming on. They have what are called “premonitory symptoms,” such as feeling lightheaded, nauseous, and heart palpitations (irregular heartbeats that feel “fluttering” in the chest). If you have syncope, you will ly be able to keep from fainting if you sit or lie down and put your legs up if you feel these symptoms.

Syncope can be a sign of a more serious condition. So, it is important to get treatment right away after you have an episode of syncope. Most patients can prevent problems with syncope once they get an accurate diagnosis and proper treatment.

What causes syncope?

Syncope can be caused by many things. Many patients have a medical condition they may or may not know about that affects the nervous system or heart. You may also have a condition that affects blood flow through your body and causes your blood pressure to drop when you change positions (for example, going from lying down to standing).

Last reviewed by a Cleveland Clinic medical professional on 05/14/2019.


Syncope, Fouad-Tarazi, F, Laura Shoemaker L, Mayuga K, Jaeger F Accessed September 4, 2014


Vasovagal syncope: Symptoms, causes, treatment, and more

Vasovagal Syncope: Symptoms, Diagnosis, Treatments

The term vasovagal syncope describes fainting that occurs in response to a sudden drop in heart rate or blood pressure. The resulting lack of blood and oxygen to the brain is what causes a person to pass out.

Doctors sometimes refer to vasovagal syncope (VVS) as neurocardiogenic syncope or reflex syncope. This condition typically occurs when the body overreacts to a stimulus that induces a state of fear or emotional distress.

Other causes may include severe pain, exhaustion, or sudden changes in body posture. Some people have a predisposition to these episodes due to a health condition that affects blood pressure or the heart.

Although a person may sometimes sustain injuries as a result of passing out, VVS is generally harmless. However, a medical diagnosis is necessary to rule out more serious medical conditions.

In this article, we outline some common symptoms and causes of vasovagal syncope. We also cover the treatment options available and provide tips on how to prevent fainting episodes.

Share on PinterestLightheadedness, dizziness, and weakness can be signs that a person will faint.

Some people who experience VVS do not notice any warning signs before fainting. Others may have symptoms such as:

People who experience these symptoms before fainting should lie down somewhere safe. Lying down will help the body maintain adequate blood flow to the brain, which may prevent fainting. It will also minimize the risk of a fall or injury in the event of fainting.

A person who has fainted may feel tired, lightheaded, or nauseated when they come round.

VVS occurs when the nerves that regulate heart rate and blood vessel constriction temporarily lose some of their normal regulation.

Malfunctions generally occur when a stimulus, such as fear, or an abrupt change in body posture causes the blood vessels to widen suddenly. This widening leads to a sudden drop in blood pressure and a resulting lack of blood and oxygen to the brain. This lack of oxygen is what causes fainting.

People may experience VVS for different reasons. Some common triggers include:

  • fear
  • the sight of blood or gore
  • getting blood drawn
  • standing for a long time
  • sudden changes in posture
  • straining, such as during bowel movementssevere pain
  • intense exercise
  • exposure to heat

A person who has experienced VVS may feel tired, weak, and nauseated when they come round. It is important that they rest before getting up and continuing with their day.

In some cases, people may need to seek emergency medical attention after a fainting episode. Generally, medical care is only necessary for people who experience the following scenarios and symptoms:

  • fainting while pregnant
  • falling from a significant height
  • sustaining a head injury or other severe injury
  • loss of consciousness
  • chest pain or difficulty breathing
  • confusion, slurred speech, or issues with vision or hearing
  • involuntary movements of the body

People who have previously experienced VVS should talk to their doctor if they experience any new triggers or symptoms.

People should also see a doctor if they experience fainting for the first time. However, it is not always possible to diagnose VVS from a single episode of fainting.

Some types of syncope can occur as a result of an underlying medical condition that requires treatment. Examples of such conditions include:

  • diabetes
  • heart disease
  • Parkinson’s disease
  • lung disease

Typically, doctors will begin a diagnosis of VVS with a review of the person’s medical history and any other symptoms. They will also conduct a physical examination. As part of this examination, the doctor will take blood pressure readings while the person is standing, sitting, and lying down.

A doctor may also attempt to rule out alternative causes of fainting using one or more tests. Examples of such tests include:

  • Electrocardiogram (EKG), which measures electrical activity in the heart.
  • Echocardiogram, which assesses heart motion and blood flow through the heart.
  • Exercise stress test to evaluate heart function in response to exercise.
  • Tilt-table test, in which the doctor will secure a person to a padded table that tilts at different angles. Various monitors detect and record heart activity, blood pressure, and oxygen levels while the table positions the person at different angles.

VVS does not typically require treatment. However, a person may sometimes be slow to regain consciousness after an episode of fainting. A bystander can intervene by laying the person on their back and raising their legs in the air. Doing this may help restore blood flow to the brain, thereby helping the person regain consciousness.

According to a 2016 review, there are limited treatment options for people with VVS. Doctors advise people with this condition to avoid known fainting triggers and take precautions to prevent injury when signs of imminent fainting begin.

Medications are not usually necessary for VVS. However, in some circumstances, the following medications may be effective in reducing the frequency of VVS episodes:

  • Alpha-1 adrenergic agonists: These drugs help raise blood pressure.
  • Fludrocortisone: A type of corticosteroid that can help maintain blood pressure by increasing sodium and fluid levels in the body.
  • Selective serotonin reuptake inhibitors (SSRIs): Antidepressant medications that may help moderate the nervous system response.

However, further studies are necessary to determine the effectiveness of these and other medical treatments for VVS.

VVS is not always completely preventable. However, a person may be able to reduce the number of fainting episodes that they experience.

A person’s doctor may provide the following recommendations for preventing VVS and the associated complications:

  • identifying and avoiding situations that trigger fainting episodes
  • engaging in moderate exercise
  • drinking plenty of fluids to maintain blood volume
  • consuming a diet that is higher in salt
  • wearing compression stockings
  • discontinuing medications that lower blood pressure
  • immediately sitting or lying down when feeling faint

As with prescription medications, these preventive lifestyle approaches may work for some people and not others. Various factors, such as the person’s blood pressure and heart function, may determine the effectiveness of these approaches.

Vasovagal syncope refers to fainting that occurs in response to a sudden drop in heart rate or blood pressure.

Vasovagal syncope is usually not dangerous. However, people should seek medical attention if they faint when pregnant, experience additional symptoms, or fall and injure themselves when fainting. People should also see a doctor if they are unsure of the cause of fainting.

There are no standard treatments for vasovagal syncope. Instead, treatment generally involves making certain dietary and lifestyle changes, as well as avoiding potential triggers of fainting.



Vasovagal Syncope: Symptoms, Diagnosis, Treatments

Vasovagal syncope is a condition that leads to fainting in some people. It is also called neurocardiogenic syncope or reflex syncope. It's the most common cause of fainting. It's usually not harmful nor a sign of a more serious problem.

Many nerves connect with your heart and blood vessels. These nerves help control the speed and force of your heartbeat. They also regulate blood pressure by controlling whether your blood vessels widen or tighten. Usually, these nerves coordinate their actions so you always get enough blood to your brain.

Under certain situations, these nerves might give an inappropriate signal. This might cause your blood vessels to open wide. At the same time, your heartbeat may slow down. Blood can pool in your legs which leads to a drop in blood pressure, and not enough of it may reach the brain. If that happens, you may briefly lose consciousness.

When you lie or fall down, blood flow to the brain resumes.

Vasovagal syncope is quite common. It most often affects children and young adults, but it can happen at any age. It happens to men and women in about equal numbers. Un some other causes of fainting, vasovagal syncope does not signal an underlying problem with the heart or brain.

Several triggers can cause vasovagal syncope. To help reduce the risk of fainting, you can stay away from some of these triggers such as:

  • Standing for long periods
  • Excess heat
  • Intense emotion, such as fear
  • Intense pain
  • The sight of blood or a needle
  • Prolonged exercise
  • Dehydration
  • Skipping meals

Other triggers include:

  • Urinating
  • Swallowing
  • Coughing
  • Having a bowel movement

Fainting is the defining symptom of vasovagal syncope. Often you may have certain symptoms before actually fainting such as:

  • Nausea
  • Warmth
  • Turning pale
  • Getting sweaty palms
  • Feeling dizzy or lightheaded
  • Blurred vision

If you can lie down at the first sign of these symptoms, you will often be able to prevent fainting. When it happens, this type of fainting almost always happens in a sitting or standing position. Not everyone notices symptoms before fainting, however.

When a person does faint, lying down restores blood flow to the brain. Consciousness should return fairly quickly. You might not feel normal for a little while after you faint. You might feel depressed or fatigued for a short time. Some people even feel nauseous and may vomit.

Some people have only 1 or 2 episodes of vasovagal syncope in their life. For others, the problem is more chronic and happens with no warning.

Your doctor will review your medical history and do a physical exam. This will probably include measuring the blood pressure while lying down, seated, and then standing.

Your doctor will ly do an electrocardiogram (ECG) as well, to evaluate the heart’s rhythm. For many children and young adults, this may be all that is needed.

Usually, the doctor can safely assume that the fainting is due to vasovagal syncope, and not some form of syncope that is more dangerous.

Sometimes the doctor needs to check for other possible causes for fainting. Because some causes of fainting are dangerous, the doctor will want to rule out these other causes. Your doctor might use tests such as the following:

  • Continuous portable ECG monitoring, to further analyze heart rhythms
  • Echocardiogram, to examine blood flow in the heart and heart motion
  • Exercise stress testing, to see how your heart works during exercise
  • Blood work, only if your doctor is suspicious for an abnormality

If these tests are normal, you might need something called a “tilt table test.” For this test, you lie down on a padded table. Someone measures your heart rate and blood pressure while you are lying down and then tilted up for a period of time. Sometime medicine is also given to trigger a fainting response. If you have vasovagal syncope, you may faint during the upward tilt.

Watch for the warning signs of vasovagal syncope, dizziness, nausea, or sweaty palms. If you have a history of vasovagal syncope and think you are about to faint, lie down right away. Tensing your arms or crossing your legs can help prevent fainting. Passively raising or propping up your legs in the air can also help.

To immediately treat someone who has fainted from vasovagal syncope, help the person lie down and lift his or her legs up in the air. This will restore blood flow to the brain, and the person should quickly regain consciousness. The person should lie down for a little while afterwards.

If you have had episodes of vasovagal syncope, your doctor might make some suggestions on how to help prevent fainting. These might include:

  • Avoiding triggers, such as standing for a long time or the sight of blood
  • Moderate exercise training
  • Discontinuing medicines that lower blood pressure, diuretics
  • Eating a higher salt diet, to help keep up blood volume
  • Drinking plenty of fluids, to maintain blood volume
  • Wearing compression stockings or abdominal binders

Occasionally, you may need medicine to help control vasovagal syncope. However, research on these medicines has revealed uncertain benefits in vasovagal syncope. These are usually only considered when a person has multiple episodes of fainting. Some of the medicines your doctor may advise a trial of include:

  • Alpha-1-adrenergic agonists, to increase blood pressure
  • Corticosteroids, to help increase the sodium and fluid levels
  • Serotonin reuptake inhibitors (SSRIs), to moderate the nervous system response

If these medicines are ineffective, doctors sometimes try orthostatic training. This method uses a tilt table to gradually increase the amount of time spent upright. Rarely, in cases where a significant slowing of the heartbeat or pausing is detected, a heart pacemaker is needed.

Vasovagal syncope itself is generally not dangerous. Of course, fainting can be dangerous if it happens at certain times, while driving. Most people with rare episodes of vasovagal syncope can drive safely.

If you have chronic syncope that is not under control, your doctor may advise against driving. This is especially ly if you don’t usually have warning signs before you faint.

Ask your doctor about what is safe for you to do.

See a doctor right away if you have recurrent episodes of passing out or other related problems.

Key points about vasovagal syncope

  • Vasovagal syncope is the most common cause of fainting. It happens when the blood vessels open too wide and/or the heartbeat slows, causing a temporary lack of blood flow to the brain.
  • It's generally not a dangerous condition.
  • To prevent fainting, stay hot places and don't stand for long periods.
  • If you feel lightheaded, nauseous, or sweaty, lie down right away and raise your legs.
  • Most people with occasional vasovagal syncope need to make only lifestyle changes such as drinking more fluids and eating more salt.
  • Some people may need medicine or even a heart pacemaker.

Tips to help you get the most from a visit to your healthcare provider:

  • Know the reason for your visit and what you want to happen.
  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your provider tells you.
  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
  • Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
  • Ask if your condition can be treated in other ways.
  • Know why a test or procedure is recommended and what the results could mean.
  • Know what to expect if you do not take the medicine or have the test or procedure.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your provider if you have questions.