A to Z Symptoms: Fainting

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A to Z Symptom: Fainting

May also be called: Syncope; Swooning; Passing Out

More to Know

In most cases, fainting — or syncope (SIN-ko-pee) — is not a sign of a dangerous problem.


Fainting happens when not enough oxygen reaches the brain due to a fall in blood pressure. Common causes include dehydration, a quick change in position, standing or sitting still for a long period, becoming overheated, hyperventilation (overbreathing), low blood sugar, anemia, sudden fear of something (for example, the sight of blood), and some heart problems.

Most cases have warning signs (such as a change in vision, dizziness, nausea, or stomach pain) that happen a few seconds before passing out.


Fainting in children, especially teens, is common but shouldn't be ignored. Discuss it with your doctor, especially if it occurs during exertion (exercising, running, etc.) or happens often. Fainting that's related to a heart problem often occurs during exercise and without warning and can include feelings of chest pain or the heart racing.

Fainting not related to the heart often can be prevented by drinking more liquids to increase the total amount of fluid in the bloodstream. Also, caffeine should be avoided. Sometimes, a doctor might recommend increasing salt in the diet as long as blood pressure is not borderline-high or high.

Keep in Mind

When warning signs of fainting occur, quickly sitting down, dropping the head between the knees, or lying down on the floor may help avoid a loss of consciousness. Then, gradually get up after the dizzy feeling has passed.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.

Related Resources

OrganizationAmerican Academy of Pediatrics (AAP) The AAP is committed to the health and well-being of infants, adolescents, and young adults. The website offers news articles and tips on health for families.
OrganizationAmerican Academy of Family Physicians This site, operated by the American Academy of Family Physicians (AAFP), provides information on family physicians and health care, a directory of family physicians, and resources on health conditions.

Related Articles

First Aid: Fainting Fainting is a loss of consciousness that can be caused by many things. Here's what to do if your child faints or is about to faint.
Breath-Holding Spells Kids who have these spells hold their breath until they pass out. Although upsetting to watch, the spells are not harmful and do not pose any serious, long-term health risks.

Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.

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