Fainting/ Syncope in children and teenagers

What is Fainting?

A faint (blackout/syncope) is a sudden loss of consciousness- not usually associated with jerking movements. The medical term for a faint is syncope. Rarely it can be due to an underlying heart condition so assessment by a clinician is advisable. The most common cause of fainting in children and teenagers though is a transient fall in blood pressure (vasovagal syncope). The latter may occur after prolonged standing particularly on a hot day, in dehydrated individuals. It can also occur in some people at the sight of blood.


Some children will have no warning of the faint or may faint during exercise. This requires a more urgent assessment. More commonly children have a warning, feeling light headed and queasy (nauseous). Then they may notice a loss of hearing and a sensation of everything becoming dark, before falling to the floor. They may appear pale and/or clammy.


A clinical examination will usually be normal. An echocardiogram will exclude structural heart disease. An ECG will also be performed to check the heart rhythm. Depending on the history a 24 hour tape, an exercise test and or a tilt test (fainting test)may be performed. In certain situations, an implantable loop recorder is used to monitor the heart rhythm over a long period of time.

Tilt test


A tilt test involves being strapped to a bed. Then the patient is tilted forward and their heart rate, ECG and blood pressure are repeatedly checked. Those with a tendency to have a vasovagal faint will have a fall in their blood pressure when they are tilted forward. They may actually faint but will not fall or injure themselves as they are strapped to the tilt table/bed. A spray may be given under the tongue to bring on symptoms. The test usually takes 1.5 to 2 hours.

Please click here for information about having a tilt test.


If there is an underlying heart condition then this will require investigation and treatment. If the cause of fainting is believed to be vasovagal syncope (simple fainting/ neurocardiogenic) the treatment is increased fluid and salt intake and regular meals. Rarely medication is required.


The outlook for children with simple fainting is excellent. Most children outgrow fainting or learn how to control their symptoms so they do not actually faint.

Dr Naqvi is an expert in disorders of the aorta including Loeys-Dietz syndrome, Marfan syndrome and undiagnosed connective tissue disorders in children. She is the Paediatric Aortopathy Marfan Lead at the Royal Brompton Hospital in Chelsea, London. She is an active member of the Pan London Aortopathy expert group and organises professional meetings on diseases of the aorta. She has also given an invited lecture at the national patient meeting for the Marfan Association at St George’s Hospital in London.

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Disclaimer: The opinions and facts shown in this article are as accurate and up to date as possible, but are provided as general “information resources”, which may not be relevant to individual persons. This article is not a substitute for individual assessment and always take advice from a paediatric cardiologist who is familiar with the particular person.