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Syncope: Causes, Symptoms, Treatment, Prognosis, Pathophysiology, Prevalence

Syncope is a condition characterized by temporary loss of consciousness and muscle strength due to low blood pressure. It is also known as fainting.

What is Syncope?

What is Syncope?

Syncope (or fainting), occurs due to temporary decrease in blood flow and oxygen to the brain. It is characterized by rapid onset, short duration and spontaneous recovery. Fainting is different from seizures during which patient loses consciousness.

In most cases, syncope is non-medical and is followed by return to full consciousness. While in other cases it maybe due to some underlying serious medical problems. However, any syncope should be considered as a medical emergency. People with recurrent problems of syncope should consult a good doctor.

Signs and Symptoms of Syncope

It is observed that patient suddenly loses consciousness and faints. The following symptoms are associated with syncope:

Signs of syncope observed when a person faints are:

  • Pale skin
  • Drop in blood pressure
  • They have weak pulse.

Prevalence Rate of Syncope

The prevalence of syncope is that it affects 3-6 individuals per thousand people every year. Syncope is more common in older people and females over the age of 80 years. In some cases, the patients have to be admitted on emergency basis to the hospitals, among which 4% of the patients expire within a month’s period.

Prognosis of Syncope

It is known to recur in 30% of the people with syncope episodes. In case of the non-cardiac cause of syncope, the 5 year mortality rate is 30%. In old aged patients with cardiac problems, 50% die within 5 years when they experience syncope.

Causes of Syncope

There is a reduced blood supply to the brain which is caused by the following factors:

  • Emotional stress
  • Pain
  • Overheating and dehydration
  • Heavy sweating
  • Violent coughing and sneezing
  • Psychiatric disorders
  • Metabolic disorders
  • During defecation (passing of stools)
  • During urination
  • Lifting a heavy weight or other physical activity
  • It may be due to side effects of some medicines.
  • Some people (especially women) faint while receiving injection or at the sight of blood due to trauma.

Syncope due to hypoxia can be due to:

  • Malfunctioning of lungs
  • Carbon monoxide poisoning
  • Due to problems in blood circulation:
    • Heart fails to pump blood
    • Blood vessels do not have enough pressure to maintain blood pressure
    • There is less blood in the blood vessels (as seen in most cases of females with anaemia).

Women who are pregnant can also experience syncope due to drop in blood pressure or excessive hormonal surge.

Pathophysiology of Syncope

Syncope is a homeostatic mechanism of the brain to let us survive. When brain blood and oxygen levels drop down considerably, brain immediately pauses the functioning of all the other non-vital parts of the body so that the focus of the brain and the resources (oxygen, blood, etc.) primarily remains only on the vital organs. When the brain senses lower levels of oxygen, in order to compensate, the breathing becomes faster (hyperventilating) to bring the oxygen levels back to normal. The heart rate (pulse) also increases to send more oxygen to the brain. This increased heart rate causes a drop in blood pressure (hypotension) in other parts of the body as the blood flow to the other body parts is reduced and the brain is flooded with blood. The occurrence of hyperventilation along with hypotension can lead to short-term loss of consciousness, syncope and muscle weakening.

Complications of Syncope

  • Frequent episodes of syncope have serious effects on the quality of life of a person. It can lead to major illness such as recurrent moderate depressive disorders, chronic arthritis and also end stage kidney diseases.
  • Morbidity is high in elderly people.
  • Recurrent syncope leads to poor quality of life.
  • It can lead to a sudden fall due to temporary fainting which can cause tissue and bone injury.

How to Diagnose the Causes of Syncope?

The patient with syncope should be examined by the doctor as fast as possible.

  • Medical History: The doctor will record the Medical history in terms of the patient’s physical activity and position, the associated symptoms before and after the event. The physician will also review the different symptoms. Information about the past medical history will also be noted in terms of any disease such as cardiac problems if present and the type of medications taken.
  • Physical Examination to Diagnose Syncope: The patient will be examined physically in terms of heart beat and blood pressure (BP). The general examination includes checking the patient’s mental status including confusion and hesitancy. There is careful examination of Jugular venous waves. This is followed by a full neurological examination.
  • Diagnostic Tests Performed to Identify the Cause of Syncope:
    • Electrocardiogram Test (ECG): To check the electrical activity of the heart.
    • Carotid Sinus: Checks the carotid sinus by rubbing the area to determine if the symptoms of dizziness and syncope are caused due to carotid sinus.
    • Blood Tests: Blood tests are done to check for anaemia, diabetes, and other infections if any.
    • Tilt-Table Test: This test monitors the patient’s blood pressure, heart rate and rhythm while the patient comes to an upright position from a lying down position. In case of a healthy person, the change in position from lying down to an upright position causes a change in the heart rate and blood pressure – this happens to ensure adequate supply of blood to the brain. If the reflexes are not working properly, this change in position can cause syncope.
    • Holter Monitor Test: The patient wears a portable device for one or two days which records the heartbeats and the electrical activity of the heart while the patient does all his/her normal activities. It is worn under clothing near to the heart. The patient is informed that in case a specific symptom is felt, a button has to be pressed, which will then record the heart rhythms of that moment more specifically and the doctor can later see the cardiac activity of that situation and evaluate the condition.

In cases where none of the reveal anything, the doctor concludes that the patient had a neurocardiogenic syncope.

Treatment of Syncope

Treatment for syncope depends on the underlying cause. Those who are at high risk for syncope following the investigation need to be admitted to the hospital for further monitoring.

  • Most patients need to be given guidance and knowledge about how to handle the problem of syncope. They should take the following action the moment the first sign of collapse occurs:
    • Sit down ideally on the ground or lie down flat with the legs raised up on a chair or against a wall, with the head placed in between the knees for 10–15 minutes, preferably in a cool and quiet place.
    • Squatting down on the heels can be very effective.

When the person starts feeling better, they should get up carefully. Ideally after syncope symptoms, one should go off to sleep. These techniques help to circulate the venous blood to the brain.

  • In case of frequent spells of syncope, treatment may be desired. Unfortunately, treatment options are limited. However, the following techniques can help in managing the condition:
    • Tilt Training: The person is trained to be in upright position for prolonged periods in a good balanced position. Several training sessions are required as deconditioning happens very easily.
    • Isometric Counterpressure Manoeuvres: Leg crossing or arm tensing can help in increasing the blood pressure high enough to prevent a syncope.
    • There is limited information on the use of Medications and cardiac pacing in treating syncope.

If the fainting episodes occur often, then syncope may be sign of an underling heart disease in which case the treatment is much more sophisticated and may involve pacemakers and cardioverter-defibrillators.

Prevention of Syncope

One cannot prevent occurrence of syncope; one can only take immediate precautions to avoid going through serious after effects. Patients should avoid triggers of events such as prolonged standing in the hot sun or taking hot water bath.


Although fainting or syncope may be temporary, however its side effects may be serious. Hence, one needs to be given proper education on how to handle them. Also people with recurrent episodes of syncope should take proper treatment to avoid undesirable accidents in their life.


  1. Medscape. (2021). Syncope. https://emedicine.medscape.com/article/811669-overview
  2. Johns Hopkins Medicine. (2021). Syncope (Fainting): Diagnosis and Treatment. https://www.hopkinsmedicine.org/health/conditions-and-diseases/syncope-fainting
  3. Cleveland Clinic. (2021). Fainting (Syncope). https://my.clevelandclinic.org/health/diseases/17669-syncope-fainting

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Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:September 4, 2023

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