Fainting
Overview
Causes
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
- Dehydration
- Long periods of standing
- Stress, trauma, or fright
Blood Flow to the Brain |
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These health problems may also cause fainting:
- Orthostatic hypotension—low blood pressure when standing
- Anemia—low iron in the blood
- Hypoglycemia—low blood glucose
- Seizures
- Stroke or transient ischemic attack
- Heart conditions
SymptomsandDiagnosis
Symptoms
Fainting is a sudden loss of consciousness that resolves in a short amount of time. Before this happens, a person may feel:
- Lightheaded
- Weak
- Nauseated
- Sweaty
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
- Confusion
- Loss of balance
- Movement problems
- Vision problems
- Severe headache
- Rapid, irregular heartbeat; chest pain
Diagnosis
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.
Treatments
Treatment
If there is an underlying cause, it will need to be treated. Treatment may not be needed for a person who only fainted once.
Prevention
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.
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