Vasovagal syncope, also called neurocardiogenic or reflex syncope is a condition that defines fainting that occurs in response due to sudden triggers like the sight of blood or extreme emotional distress. This trigger mainly causes drop in the heart rate and blood pressure leading to reduced blood flow to the brain, causing you to briefly lose consciousness. Although, this syndrome is commonly seen in both males and females equally and can happen to anyone, children and young adults tend to react to this condition more.

In general, the vasovagal syncope syndrome is harmless and requires no treatment but if the episodes continue frequently, the doctor may recommend tests and treatment to rule out more-serious causes of fainting.

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Vasovagal syncope


The human body has special nerves that help control how fast the heart beats and also works together to regulate the blood pressure by controlling the width of your blood vessels. The nerves work together to ensure that the brain always receive enough oxygen-rich blood. But in case of Vasovagal syncope, when you have a sudden reaction in response to an external trigger like sight of blood or intense emotional distress, the nerve signals get all mixed up causing the blood vessels to suddenly open wide, slowing the heart rate and the dropping in blood pressure levels which directly leads to blood pooling in your legs. This dip in blood pressure and slowed heart rate quickly reduces the blood flow to the brain, and causes one to faint.

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Common vasovagal syncope triggers include:

  • Sight of blood
  • Standing for long periods of time
  • Intense exposure to heat
  • Having blood drawn
  • Fear of bodily injury
  • Straining, such as to have a bowel movement
  • Intense physical activity
  • Severe pain
  • Intense coughing
  • Sudden changes in posture


Well, one might not feel or get any kind of characteristic symptoms before fainting, but some people do experience some of the following signs and symptoms. This includes:

  • Pale or gray skin
  • Lightheadedness
  • Tunnel vision
  • Blurred vision
  • Nausea
  • Feeling warm
  • Feeling clammy or sweaty
  • Weakness

During an episode of vasovagal syncope, bystanders may notice these symptoms in the affected person:

  • Jerky, abnormal movements
  • Dilated pupils
  • Weak and slow pulse

Diagnosis And Treatment

Well, one cannot observe the symptoms beforehand and go to a doctor but in case you have a sudden episode of vasovagal syncope, do consult a doctor afterwards to analyze any underlying condition. The doctor usually does a thorough physical examination, listens to the heart beat and takes blood pressure readings. The doctor may also massage the main arteries in the neck to see if that causes you to feel unconscious. However, to rule out any underlying conditions, the doctor may conduct the following diagnostics:

Blood tests: It looks for conditions like anemia that can contribute to fainting.

Electrocardiogram: This test mainly records the electrical signals the heart produces and can also detect irregular heart rhythms and other cardiac problems.

Echocardiogram: This test uses sound waves to produce ultrasound images of the heart to look for conditions, such as valve problems.

Tilt-table test: This test allows the doctor to check the heart rate and blood pressure when you’re in different positions by tilting at various angles.

Portable Holter monitor: This device gives a detailed 24-hour heart rhythm analysis.

Exercise stress test: This test analyzes heart rhythm while exercising, walking briskly or running on a treadmill.


Although in most cases of vasovagal syncope, treatment is not necessary, but if you do experience frequent episodes of syncope, the doctor may suggest the following:

  • Medications including selective serotonin reuptake inhibitors or the ones to treat low blood pressure
  • Therapies to decrease the pooling of blood in the legs
  • Surgery to insert an electrical pacemaker to regulate the heartbeat