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Fainting is a sudden, brief loss
of consciousness. When people faint, or pass out, they usually fall down. After
they are lying down, most people will recover quickly.
doctors use for fainting is
syncope (say "SING-kuh-pee").
one time is usually nothing to worry about. But it is a good idea to see your
doctor, because fainting could have a serious cause.
Fainting is caused by a drop
in blood flow to the brain. After you lose consciousness and fall or lie down,
more blood can flow to your brain so you wake up again.
Most causes of fainting are usually not signs of a more serious illness. In these cases, you faint because
Fainting caused by the vasovagal reflex is often easy to
predict. It happens to some people every time they have to get a shot or they
see blood. Some people know they are going to faint because they have symptoms
beforehand, such as feeling weak, nauseated, hot, or dizzy. After they wake up,
they may feel confused, dizzy, or ill for a while.
Some causes of
fainting can be serious. These include:
Sometimes the cause is unknown.
Fainting may be the sign of a serious problem if:
To find the
cause of fainting, a doctor will do a physical exam and ask questions about the
fainting episode. You can help your doctor by being prepared to describe what
happened before you fainted, how long you were "out," and how you felt when you
Depending on what the physical exam shows, the doctor may
want to do tests. These tests may include:
If you know you tend to faint at certain times (such as
when you get a shot or have blood drawn), it may help to:
You may need to see a doctor if you have ongoing dizziness or fainting.
Other Works Consulted
Shen W-K, et al. (2017). 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope. Circulation, published online March 9, 2017. DOI: 10.1161/CIR.0000000000000499. Accessed March 30, 2017.
ByHealthwise StaffPrimary Medical ReviewerWilliam H. Blahd, Jr., MD, FACEP - Emergency MedicineAdam Husney, MD - Family MedicineKathleen Romito, MD - Family MedicineSpecialist Medical ReviewerElizabeth T. Russo, MD - Internal Medicine
Current as ofMay 15, 2017
Current as of:
May 15, 2017
William H. Blahd, Jr., MD, FACEP - Emergency Medicine
& Adam Husney, MD - Family Medicine & Kathleen Romito, MD - Family Medicine & Elizabeth T. Russo, MD - Internal Medicine
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