Fainting

Fainting is a momentary episode of unconsciousness caused by a sudden drop in blood pressure. Blood vessels continually adjust their diameter to ensure a constant blood pressure. For instance, the vessels constrict when we stand up to counteract the effects of gravity.

Temporary low blood pressure can be caused by various events that prompt blood vessels to dilate, including extreme heat, emotional distress or pain. The lack of blood to the brain causes a lapse of consciousness.

Most fainting will be transient and not serious. Usually a fainting episode will only last a few seconds though feeling unwell and recovery may take several minutes. If a person doesn’t recover quickly, always seek urgent medical attention. Occasionally a collapse may be caused by a more serious event such as a stroke or a disturbance in the normal heart rhythm.

Symptoms of fainting

The symptoms of a faint include:

• Dizziness
• Light headedness
• A pale face
• Perspiration
• Heightened anxiety and restlessness
• Nausea
• Collapse
• Unconsciousness, for a few seconds
• Full recovery after a few minutes.

Complaints of breathlessness, chest pains, heart palpitations or noting the pulse to be faster or slower than expected should have further medical investigation. Similarly, signs of slurred speech, facial droop or weakness in any limbs should also be considered more serious.

Causes for a drop in blood pressure

A temporary drop in blood pressure can be caused by different factors, including:

• Prolonged standing
• Extreme heat, which shunts blood away from the main circulatory system and into the vessels of the skin
• Emotional distress
• Severe pain
• The sight of blood
• The sight of a hypodermic needle
• Other events that a person may find distressing.

What to do if you feel faint

If possible, lie down and elevate the feet. This may prevent a loss of consciousness. Fresh air can also help, especially if you are feeling hot. If it is not possible to lie down, put your head down as low as possible.

If you do faint, remain lying down for ten minutes. Sit up slowly when you need to get up.

First aid and fainting

First aid treatment for a person who has fainted includes:

• Helping the person lie down. A person who has fainted in a chair should be helped to the ground.
• If the person is unconscious, roll them on their side. Check they are breathing and have a pulse.
• If possible, elevate the person’s feet above the height of their head.
• If the fainting episode was brought on by heat, remove or loosen clothes and try to cool the person down by wiping them with a wet cloth or fanning them.
• Assess the person for any potential injuries if they have fallen.
• In an emergency, always call triple zero (000) for an ambulance if the person has not regained consciousness within a few seconds or recovered in a few minutes.

Orthostatic hypotension

Blood vessels respond to gravity by constricting. This increases or maintains blood pressure when we stand from a sitting or lying position.

Orthostatic hypotension means that the blood vessels don’t adjust to a standing position but instead allow the blood pressure to drop, which can trigger a fainting episode.

Causes of orthostatic hypotension include:

• Nervous system diseases, such as neuropathy
• Prolonged bed rest
• Dehydration
• Irregular heart beat (heart arrhythmia)
• Changes in blood pressure medication.

Hypotension

Low blood pressure (hypotension) is a condition characterised by blood pressure that is lower than normal or usual for the person.

Hypotension can be caused by a variety of factors including heart disease and abnormal heart rhythms, some infections, dehydration and medications for high blood pressure or certain heart conditions. Low blood pressure can also be caused by a rare disorder of the adrenal glands called Addison’s disease. Frequent fainting spells or sensations of light headedness need to be medically investigated to check for underlying causes.

Where to get help

• Your doctor
• In an emergency, always call triple zero (000).

Things to remember

• Common causes of fainting include heat, pain, distress, the sight of blood or anxiety and hyperventilating.
• Lying the person down will often improve the person’s condition.
• Frequent fainting spells need to be medically investigated to check for underlying causes.

You might also be interested in:

• Blood pressure.
  
• Dizziness and vertigo.
  
• Long QT syndrome.
  

Want to know more?

Go to More information for support groups, related links and references.

This page has been produced in consultation with and approved by:

(Logo links to further information)

Ambulance Victoria

Last reviewed: November 2011

Content on this website is provided for education and information purposes only. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your doctor or other registered health professional. Content has been prepared for Victorian residents and wider Australian audiences, and was accurate at the time of publication. Readers should note that, over time, currency and completeness of the information may change. All users are urged to always seek advice from a registered health care professional for diagnosis and answers to their medical questions.

If you would like to link to this fact sheet on your website, simply copy the code below and add it to your page:

<a href="http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Fainting?open">Fainting - Better Health Channel</a><br/>
Fainting is a momentary episode of unconsciousness caused by a sudden drop in blood pressure. Common causes include heat, pain or distress. If you feel faint, lie down and elevate your feet. You can get up slowly after ten minutes. If a person doesn't recover quickly, always seek urgent medical attention. The collapse could have been triggered by a more serious event such as cerebral haemorrhage (stroke).

Content on this website is provided for education and information purposes only. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your qualified health professional. Content has been prepared for Victorian residence and wider Australian audiences, and was accurate at the time of publication. Readers should note that over time currency and completeness of the information may change. All users are urged to always seek advice from a qualified health care professional for diagnosis and answers to their medical questions.

For the latest updates and more information, visit www.betterhealth.vic.gov.au

Copyight © 1999/2012  State of Victoria. Reproduced from the Better Health Channel (www.betterhealth.vic.gov.au) at no cost with permission of the Victorian Minister for Health. Unauthorised reproduction and other uses comprised in the copyright are prohibited without permission.