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Clinical Specialties - Cardiac

Symptoms, Causes and Types of Syncope (Fainting)

What are the symptoms?

The most common symptoms of syncope include:

  • Blacking out
  • Feeling dizzy or lightheaded
  • Falling for no reason
  • Nausea (feeling sick) or vomiting
  • 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


In some instances, you can feel a fainting episode coming on. You can have what are called 'premonitory symptoms' such as feeling lightheaded, experiencing nausea or having heart palpitations (irregular heartbeats that feel like 'fluttering' in the chest). If you suffer from syncope, you may be able to prevent yourself from fainting if you sit or lie down and put your legs up as soon as you feel these symptoms.

Syncope can be a sign of a more serious condition, so it is important that you speak to your General Practitioner (GP) if you regularly suffer from any of the symptoms. Often syncope can be avoided once you get an accurate diagnosis and proper treatment.

What types of syncope (fainting) are there?

There can be a number of causes of fainting (syncope) but the main types are:

  • Cardiac: these episodes often occur without warning (no preceding symptoms prior) and can be caused by an abnormal beating of the heart (arrhythmias) or a vascular or structural heart issue. They can often be picked up by a simple electrocardiogram (ECG) test which monitors electrical activity of the heart
  • Neurological: these episodes are a result of disturbance to the electrical activity in the brain
  • Reflex: these episodes are often caused by a disturbance in either the heart rate or blood pressure that is controlled by nerves in the brain. Generally termed 'situational' (from coughing, sneezing, post-exercise etc) or 'vasovagal' (from emotions such as fear, pain, blood phobias etc) they tend to be the more common type of faint and are usually harmless
  • Orthostatic: these episodes are often caused by a sudden drop in blood pressure upon standing. Orthostatic hypotension – also called postural hypotension - can be caused by a number of factors including dehydration, some medications or even standing up too quickly
  • Other: even after extensive investigations, sometimes it is difficult to determine a cause for these events in up to 20 per cent of people


With so many potential causes, the majority of people who faint end up seeing multiple specialists over a long period of time before they receive a correct diagnosis. This can be frustrating and costly.

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