Fainting happens when there is a decrease in blood flow to the brain. There are many health problems that can cause fainting.
Some things that can trigger fainting are:
- Extreme heat
- Long periods of standing
- Stress, trauma, or fright
|Blood Flow to the Brain|
|Copyright © Nucleus Medical Media, Inc.|
These health problems may also cause fainting:
- Orthostatic hypotension—low blood pressure when standing
- Anemia—low iron in the blood
- Hypoglycemia—low blood glucose
- Stroke or transient ischemic attack
- Heart conditions
Fainting is a sudden loss of consciousness that resolves in a short amount of time. Before this happens, a person may feel:
When Should I Call My Doctor?
Call your doctor if you are having periods of fainting. This is important if you:
- Have a heart condition
- Have a job where you or others may be at risk if you faint, such as an airline pilot, bus driver, or machinist
When Should I Call for Medical Help Right Away?
Call for emergency medical services right away if you have:
- Weakness or numbness of the face, arm, or leg, especially on the left side of the body
- Loss of balance
- Movement problems
- Vision problems
- Severe headache
- Rapid, irregular heartbeat; chest pain
The doctor will ask about your symptoms and health history. You will also be asked what you were doing when this symptom happened. A physical exam will be done. This is often enough to make the diagnosis. More tests may need to be done. The tests that are done depend on what the doctor believes may be the cause.
Some underlying health problems cause people to faint. They will need to be treated.
People who feel as though they may faint can lower the risk with movements that promote blood flow to the brain, such as:
- Crossing your legs while tensing the muscles of legs, belly, and buttocks.
- Squeezing a rubber ball or other object as hard as possible.
- Gripping one hand with the other while tensing both arms and raising the elbows slightly.
This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.
Edits to original content made by Denver Health.
Copyright © EBSCO Information Services
All rights reserved.
American Heart Association http://www.heart.org
Family Doctor—American Academy of Family Physicians http://familydoctor.org
Brignole M, Moya A, et al. 2018 ESC Guidelines for the diagnosis and management of syncope. Eur Heart J. 2018 Jun 1;39(21):1883-1948.
Choosing wisely. EBSCO DynaMed website. Available at: https://www.dynamed.com/quality-improvement/choosing-wisely . Updated June 24, 2019. Accessed April 9, 2020.
Fainting. Family Doctor—American Academy of Family Physicians website. Available at: http://familydoctor.org/familydoctor/en/diseases-conditions/fainting.html. Updated December 6, 2017. Accessed April 9, 2020.
Syncope—approach to the patient. EBSCO DynaMed website. Available at: https://www.dynamed.com/approach-to/syncope-approach-to-the-patient . Updated July 9, 2019. Accessed April 9, 2020.
3/24/2015 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed: Mills PB, Fung CK, et al. Nonpharmacologic management of orthostatic hypotension: A systematic review. Arch Phys Med Rehab. 2015;96(20:366-375.