Fainting - Diagnosing fainting

In some cases of fainting, you'll need to see a healthcare professional after the fainting episode to investigate whether there's an underlying health condition.

Your GP will be able to diagnose the cause and determine whether further investigation and treatment are needed.

When to see your GP

Most cases of fainting aren't a cause for concern and don't require treatment, but you should see your GP if you're at all concerned.

You should also see your GP after fainting and you:

have no previous history of fainting
experience repeated episodes of fainting
injure yourself during a faint
have diabetes – a lifelong condition that causes your blood glucose level to become too high
are pregnant
have a history of heart disease – where your heart's blood supply is blocked or interrupted
experienced chest pains, an irregular heartbeat or a pounding heartbeat before you lost consciousness
experienced a loss of bladder or bowel control
took longer than a few minutes to regain consciousness

During an assessment after a fainting episode, your GP will ask about the circumstances surrounding your fainting episodes and your recent medical history. They may also measure your blood pressure and listen to your heartbeat using a stethoscope.

Electrocardiogram (ECG)

If your GP thinks your fainting episode may have been caused by a heart problem, they may suggest that you have an electrocardiogram (ECG).

An ECG records your heart's rhythm and electrical activity. A number of small, sticky patches called electrodes are placed on your arms, legs and chest. Wires connect the electrodes to an ECG machine.

Every time your heart beats, it produces tiny electrical signals. The ECG machine traces these signals on paper, recording any abnormalities in your heartbeat.

An ECG is usually carried out at a hospital or GP surgery. The procedure is painless and takes about five minutes.

Carotid sinus test

If your GP thinks that your fainting episode was associated with carotid sinus syndrome, they may massage your carotid sinus to see whether it makes you feel faint or lightheaded.

The carotid sinus is a collection of sensors in the carotid artery, which is the main artery in your neck that supplies blood to your brain.

If the carotid sinus massage causes symptoms, it may indicate that you have carotid sinus syndrome (see causes of fainting for more information).

Blood tests

Blood tests may be carried out to rule out conditions such as diabetes or anaemia (a condition where the body doesn't produce enough oxygen-rich red blood cells).

Your GP may measure your blood pressure while you're lying down, and again after you stand up. You may have orthostatic hypotension if your blood pressure falls after you stand up.

If you have orthostatic hypotension, you may be asked further questions to help determine the cause. For example, it can sometimes occur as a side effect of taking some medications.

Next steps

If tests reveal an underlying cause of your fainting, such as a heart problem or orthostatic hypotension, your GP may recommend treatment for fainting.