Fainting is also known as syncope, which is a complete or partial loss of consciousness with an interruption of awareness of oneself and one’s surroundings. This loss of consciousness is temporary and there is usually a spontaneous recovery. It is caused by a reduction of blood flow to the brain which causes a shortage of oxygen and leads to lightheadedness or a blackout (loss of consciousness).


Dizziness, clamminess of the skin, dimming of the vision and a weakness in the limbs leading to physical collapse.


Temporary impairment of blood to the brain can be the result of heart conditions or other causes:

  • Heart related causes: Abnormal heart rhythms (beating too fast or too slow). Abnormalities of the heart valves (aortic or pulmonic valve stenosis). High blood pressure in the arteries supplying the lungs (pulmonary artery hypertension). Tears in the aorta. Widespread disease of the heart muscle (cardiomyopathy).
  • Other causes :
  • Postural (orthostatic) hypotension – drop in blood pressure due to changing body position to vertical after lying or sitting (eg. standing up too quickly)
  • Dehydration -causing a decrease in blood volume
  • Blood pressure medications leading to low blood pressure
  • Diseases of the nerves to the legs (especially in older people, in this case diabetes and Parkinsons plays a role) when the poor condition of the nerves of the legs draws blood into the legs from the brain.
  • High altitude
  • Brain stroke or near stroke (transient ischemic attack)
  • Migraine
  • Some people may also faint during certain events such as giving blood, urinating, defecating, coughing or swallowing excessively.


How to stop yourself from fainting once symptoms appear

The blood supply needs to be returned to the brain so the person should be positioned on the ground, on their back, with their legs elevated, or they can sit on the ground with their head between their knees. The dizziness should pass and vision will return. Most feel nauseous, have a sore throat or general shakiness after a faint.

How to prevent fainting

Avoid trigger situations.

  • Get up slowly after sitting or lying down
  • Don’t strain while eliminating
  • Lie down when giving or drawing blood
  • Medication should be reviewed regularly and persons should eat proper meals to prevent a change in blood pressure and sugar
  • In the case of elderly persons who have a history of fainting (normally linked to diabetes), refined sugar must be avoided and they should eat small but frequent meals.


Source: Camelot pathophysiology, 2013 manual. Page 34-35.