Vasovagal Syncope: Symptoms, Causes And Treatment

In most cases, vasovagal syncope is a transient, uneventful illness. Only rarely is it associated with more important ailments. Recovery is almost always spontaneous, fast, and does not require treatment. 
Vasovagal syncope: symptoms, causes and treatment

Vasovagal syncope manifests itself as a brief loss of consciousness. Most of us have certainly experienced an episode of this type or at least the symptoms that precede it (called presyncope).

It generally lacks major consequences. Only in a small percentage is it a noteworthy disorder. It is estimated that 3% of this type of syncope requires medical attention and only 1% requires hospitalization.

Very often vasovagal syncope has no repercussions, except for any effects of the fall. However, when you repeatedly suffer from these episodes, without a disease to explain them, your quality of life suffers greatly.

What is vasovagal syncope?

Girl with dizziness.

Vasovagal syncope is what we commonly call fainting. It is defined as a brief and sudden loss of knowledge. This involves the inability to stand up and the loss of postural tone. Recovery occurs spontaneously.

The mechanism of vasovagal syncope is triggered when the vagus nerve is stimulated by a trigger. The intervention of the parasympathetic system causes the heart rate to slow down and the blood vessels to dilate.

As a result of this, less blood reaches the brain, so syncope or fainting occurs. Syncope is classified into three types, depending on the duration:

  • Slight or presyncope. There is no loss of consciousness in the strict sense; you experience severe dizziness.
  • Moderate. The fainting lasts for a few seconds.
  • Severe. It lasts 10-15 seconds and can cause seizures.


Vasovagal syncope accounts for 75% of syncope cases. It most often occurs in healthy patients, typically with normal blood pressure, although a condition called orthostatic hypotension is present in a small group of people. Symptoms that usually precede this type of syncope are:

  • Yawns.
  • Weakness.
  • Heat.
  • Anxiety and hyperventilation.
  • Dizziness.
  • Nausea.
  • Pallor.
  • Palpitations.
  • Reduction of the visual field.
  • Buzzing and plugged ears.
  • Difficulty in breathing
  • Impending feeling of unconsciousness.

These symptoms are not always present, sometimes the syncope is sudden. Paleness, cold skin, heavy sweating and dilated pupils are common during fainting. After a moment of mental confusion and disorientation, one gradually regains consciousness. In some cases there may be faecal or urinary incontinence.


Fainting of a person.

The causes are not fully established. It is known that during syncope, blood drains from the brain and accumulates in the legs, leading to a drop in blood pressure and loss of consciousness. Factors that can contribute to this condition include:

  • Prolonged standing position.
  • Exposure to a heat source for a prolonged period.
  • Drawing blood or seeing blood.
  • Intense effort.
  • Hunger.
  • Stale air.
  • Altitude change.
  • Strong smells.

Syncope is often caused by an abrupt change of position or emotional distress. Other times the triggers are alcohol consumption, a low-salt diet, or an allergy to a drug.

Treatment of vasovagal syncope

When it comes to an isolated episode, vasovagal syncope requires no treatment other than immediate recovery. It is recommended that the person lie down and raise their legs so that the blood circulates normally.

If syncope is recurrent, it is best to see your doctor, who will likely order a stress test and / or a tilt test. Based on the results, he or she may recommend drug treatment or suggest lifestyle changes to prevent new episodes. In some cases, for example, graduated compression stockings are useful to reduce the accumulation of blood in the legs.

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