What is syncope? 

    Syncope is the medical term for fainting. It describes what happens when you pass out. Syncope is a sudden loss of consciousness, followed by a quick and complete recovery (coming to). Syncope is very common. One out of three people will faint at some point in life.

    What causes syncope?

    To function properly, your brain needs the oxygen your blood supplies. Fainting occurs when there is an interruption to the brain's blood supply. This can happen if:

    •    Your heart beats too slowly or your blood vessels expand. This is called ’vasovagal syncope’ and can be caused by extreme emotion (shock or fear), severe pain, or an unusual response to normal body functions such as coughing or urinating

    •    Your heart beats too quickly or too slowly for a different reason than vasovagal syncope, usually related to a heart problem or caused by the side effects of some medicines

    •    Your heart cannot pump out enough blood because something is blocking the flow of blood. This happens with some kinds of heart conditions

    •    Your blood pressure drops when you stand or sit up. Causes can include not drinking enough water, drinking alcohol, health problems that affect blood pressure and side effects from some medicines

    Is fainting dangerous?

    It can be dangerous if you fall and hurt yourself when you faint. It can also be dangerous if you pass out while driving. Although fainting is usually not a sign of any serious problem, you should let your doctor know when you have a fainting spell.

    What will the doctor do to find out what is causing my syncope?

    Your doctor will probably check your blood pressure and heart rate while you are sitting, lying down and standing up. This may help show if something is wrong with the heart valves or heart muscle. It is important to tell your doctor about all the medicines you are taking, including over-the-counter and herbal medicines. One of these medicines, alone or in combination with another medicine, could be causing your problem.

    Are there tests that can help show what is causing me to faint?

    If syncope is an ongoing problem, your doctor may order an electrocardiogram (EKG) to see whether your heart beat is normal. There are other tests, including a tilt table test and an exercise test, that show how your heart beats in different circumstances. These tests can be ordered if the problem persists.

    What can I do to keep from fainting?

    If you and your doctor can find out what is causing you to faint, you can avoid those activities or figure out a way to do them more safely. For instance, standing and sitting up slowly may help. Lying down with your feet up when you feel light-headed or dizzy may help bring oxygen-rich blood back to your head. If you have circulation problems, wearing elastic compression stockings can keep blood from pooling in your legs.

    What is the treatment for syncope? 

    In most cases, no treatment is required. You may have an episode of fainting and never have the problem again. If your problem continues, your doctor may prescribe medicine to keep your heart beat even or do more tests to find out what is causing you to faint.

    This document is not a substitute for your care team’s medical advice and should not be relied upon for treatment for specific medical conditions.

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