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Vasovagal Syncope - Causes, Symptoms, Diagnosis, Treatment, and Prevention

Written by
Dr. Sneha Kannan
and medically reviewed by Dr. Vijay Kumar Kumawat

Published on Nov 06, 2019   -  4 min read



When a person faints or loses consciousness due to triggers like extreme emotional stress, it is called vasovagal syncope. Read the article to learn about its causes, symptoms, diagnosis, treatment, and prevention.

Vasovagal Syncope - Causes, Symptoms, Diagnosis, Treatment, and Prevention

What Is Vasovagal Syncope?

Fainting or passing out is called syncope. When one faints because of the overreaction of your body to certain triggers like extreme emotional stress or seeing a snake or blood is called vasovagal syncope or neurocardiogenic syncope. Such triggers drop the heart rate and blood pressure rapidly, which leads to reduced blood flow to the brain. This loss of blood flow is what causes a brief loss of consciousness.

Such episodes of vasovagal syncope are usually harmless and get better without any treatment. You might need treatment if you injured yourself while falling when you lose consciousness. As fainting is also a symptom of other serious underlying conditions, your doctor will run tests to rule out such diseases.

What Happens During a Vasovagal Syncope?

Special nerves that are present throughout the body help control the heart rate. These nerves also regulate blood pressure by dilating and constricting the blood vessels. Normally, these nerves work in harmony so that enough blood always reaches the brain.

But in cases where some triggers result in the dilation of the blood vessels, these nerve signals get mixed up. This results in a slower heart rate and a drop in the blood pressure, which causes a reduction in the amount of blood reaching the brain. Blood starts pooling in your feet and does not reach the brain, and you pass out. As you lose consciousness and fall or sit, the blood flow to the brain restarts and you feel better.

What Can Cause a Vasovagal Syncope?

Certain triggers that can cause a vasovagal syncope are:

What Are the Symptoms of Vasovagal Syncope?

Most people do not have any sign or symptom that indicates that they are going to faint. But a few of them have the following signs and symptoms for a brief moment before they fall:

  • Pale skin.

  • Dizziness.

  • Cold and clammy skin.

  • Excess perspiration.

  • Blurred vision.

  • Nausea.

  • Fatigue.

  • Feeling warm.

  • Yawning.

During syncope, the signs include:

  • Dilated pupil.

  • Abnormal jerky movements.

  • Thready pulse.

If you are having the above signs before you faint, it is best to sit or lie down so that more blood will reach your brain. This might also prevent you from losing consciousness.

When to See a Doctor for Vasovagal Syncope?

It is best to consult a doctor after an episode of fainting. Your doctor might rule out other conditions that cause fainting and will diagnose it as a vasovagal syncope. Get immediate help if along with fainting you notice new symptoms or there are frequent episodes. The following conditions make a person prone to fainting:

Do not stop taking the medicine if you thing medicines are the cause. Consult your doctor as they will prescribe alternative medicines.

Get immediate medical help in the following situations:

  • If you injure your head during the fall.

  • If you took more than a minute to regain consciousness.

  • If you feel confused after fainting.

  • If you have breathing problems, chest pain, or chest tightness.

  • If you have speech, hearing, or vision problem.

  • If you had a seizure.

  • If you are pregnant.

How Is a Vasovagal Syncope Diagnosed?

Tests are done to rule out conditions like heart diseases and diabetes. You might need to get the following tests done:

  • Electrocardiogram - To detect irregular heart rhythms and other heart diseases, by monitoring the electrical signals of the heart.

  • Echocardiogram - Here, high-frequency sound waves are used to produce images of the heart to rule out heart valve problems.

  • Treadmill test or stress test - Here, the heart rate and rhythms are monitored while the patient runs on a treadmill.

  • Blood tests - To rule out conditions like diabetes and anemia.

  • Tilt table test - If all other test results are normal, your doctor might suggest you undergo this test. Here the patient lies flat on a table, and the table tilts you from various angles. During this procedure, the heart rhythms and blood pressure are monitored to see if there are changes with the change in position.

What Are the Treatment Options for Vasovagal Syncope?

Vasovagal syncope usually does not need treatment. Try to avoid triggers and prevent head injury when you faint.


Medicines are not very effective in treating this condition. But if you are having frequent episodes, then your doctor might prescribe these medicines:

  • To raise your blood pressure - Alpha-1-adrenergic agonists.

  • To raise sodium and fluid levels - Corticosteroids.

  • To regulate the response of the nervous system - Selective serotonin reuptake inhibitors (SSRIs).


To reduce the pooling of blood in your legs, you can do foot exercises or wear compression socks.


In case you have frequent episodes of fainting, then your doctor might suggest getting a pacemaker. This machine helps regulate the heartbeat.

Can Vasovagal Syncope Be Prevented?

It is not always possible to prevent these episodes. But you can identify and prevent triggers, avoid standing for a long time, consume more salt if your blood pressure is normal, and sit down immediately when you start having signs of syncope.

For more information on this condition, consult a doctor online through phone or video consultation.


This is a sponsored video. icliniq or icliniq doctors do not endorse the content/ad in the video.

Last reviewed at:
06 Nov 2019  -  4 min read




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