Fainting is a loss of consciousness that happens quickly and sometimes without warning. A fainting episode usually resolves within seconds to minutes. If fainting is caused by another condition, then the condition will need to be treated.
In general, fainting is caused by decreased blood flow to the brain.
Blood Flow to the Brain
Copyright © Nucleus Medical Media, Inc.
Decreased blood flow to the brain can be caused by:
Most commonly, vasovagal spells. Vasovagal spells can occur:
- During medical procedures
- During times of high stress, trauma, or fright
- After standing still for a long period of time
Fainting can also occur as a side effect to medications. These include:
- Blood pressure medications
- Medications to regulate heart rhythms
- Certain antidepressants
Factors that increase your risk of fainting include having a history of fainting.
Symptoms may include:
- Sudden loss of consciousness
- Inability to remain standing or sitting
- Consciousness regained without any need for intervention
- Dizziness or lightheadedness before losing consciousness
Call your doctor if you are having episodes of fainting. This is especially important if you:
- Have a heart condition
- Have a job where you or others may be at risk if you faint. Examples include airline pilot, bus driver, or machinist.
Call for emergency medical services right away if you have:
- Weakness or numbness of face, arm, or leg, especially on the left side of the body
- Loss of balance, coordination problems
- Vision problems
- Severe headache
- Rapid, irregular heartbeat; chest pain
Your doctor will ask about your symptoms and medical history. A physical exam will be done.
Tests may include:
If initial tests are unclear, brain images may be taken. This can be done with:
Treatment will depend on the underlying condition that has caused fainting. This may include medications, lifestyle changes, or surgery.
If you are prone to fainting:
- Know the warning signs. If you feel that you are going to faint, sit or lie down right away.
- Get up slowly and carefully from lying down. Start by sitting up for a minute and then stand up.
- Drink plenty of fluids.
- Discuss dietary changes with your doctor.
- Avoid using alcohol or other drugs.
There are certain physical maneuvers that rapidly raise blood pressure and blood flow to the brain. They are called physical counterpressure maneuvers. When these are done during warning signs, you may be able to prevent fainting. Examples include:
- Crossing your legs while tensing the muscles of legs, abdomen, and buttocks.
- Forcefully squeezing a rubber ball or other object as hard as possible. Try to use your dominant hand.
- Gripping one hand with the other while tensing both arms and raising the elbows slightly.
Benditt D, Goldstein M. Fainting. American Heart Association, Circulation website. Available at:
http://circ.ahajournals.org/content/106/9/1048.full. Published 2002. Accessed April 25, 2013.
Chen LY, Benditt DG, et al. Management of syncope in adults: an update.
Mayo Clin Proc.
Fainting. American Academy of Family Physicians Family Doctor website. Available at:
http://familydoctor.org/familydoctor/en/diseases-conditions/fainting.html. Updated July 2010. Accessed April 25, 2013.
Miller TH, Kruse JE. Evaluation of syncope.
Am Fam Physician.
Syncope evaluation. EBSCO DynaMed website. Available at:
http://www.ebscohost.com/dynamed. Updated March 5, 2013. Accessed April 25, 2013.
2/6/2007 DynaMed's Systematic Literature Surveillance. Available at:
http://www.ebscohost.com/dynamed: van Dijk N, Quartieri F, Blanc JJ, et al.
Effectiveness of physical counterpressure maneuvers in preventing vasovagal syncope: the Physical Counterpressure Manoeuvres Trial (PC-Trial).
J Am Coll Cardiol.
4/1/2014 DynaMed's Systematic Literature Surveillance
http://www.ebscohost.com/dynamed: Choosing wisely. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated March 26, 2014. Accessed April 1, 2014.
Last reviewed March 2014 by Rimas Lukas, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
Copyright © EBSCO Publishing. All rights reserved.