Fainting

Also called Syncope, Blackout, Passing out

Usually harmless. The exceptions are fainting while lying down, during exercise, or with no warning at all, and those need a heart tracing.

What it is

A brief loss of consciousness caused by a temporary drop in blood flow to the brain, with rapid and complete recovery.

Most fainting is the ordinary kind, triggered by standing too long, heat, pain, the sight of blood, straining, or a shock. The body over-corrects, the heart slows, blood pressure falls, and consciousness goes for a few seconds.

Three patterns are different and matter: fainting during exercise, fainting while lying down or sitting, and fainting with no warning at all. Those can mean a heart rhythm or structural heart problem, and they need an ECG and specialist assessment rather than reassurance.

A family history of sudden death under 40 is another reason to escalate.

Fainting in older people is commonly caused by medication, dehydration or a drop in blood pressure on standing, and is frequently recorded as a fall instead. That relabelling means the cause is never looked for.

Brief jerking of the limbs during a faint is common and does not mean epilepsy.

Signs you might notice

Before: feeling light-headed, hot or sweaty, nausea, ringing in the ears, vision greying or narrowing.

During: brief loss of consciousness, pale skin, sometimes a few jerks.

After: rapid and complete recovery, though feeling washed out for an hour or two is normal.

Suggesting a heart cause and needing urgent assessment: fainting during exertion, fainting while lying or sitting, no warning at all, chest pain or palpitations first, a family history of sudden death under 40, or known heart disease.

Suggesting a seizure rather than a faint: prolonged confusion afterwards, tongue biting at the side, and a slow recovery over many minutes.

How it can affect day-to-day life

Repeated fainting is genuinely disabling because of the fear rather than the events. People stop driving, stop travelling alone, stop showering when the house is empty.

Driving rules apply after a blackout and depend on the cause. Not reporting it, and not asking, is common and risky.

In older people the important question is what they were taking and how much they had drunk. Blood pressure tablets, diuretics, and heat are the usual answer, and the fix is often a medication review. See dehydration.

For young people, the classic pattern is fainting in assembly or on a hot morning, and it is nearly always harmless once a heart cause has been excluded.

Supporting someone well

Lie the person flat and raise their legs. Do not sit them up, and do not prop them in a chair, which keeps the brain starved.

Stay with them and check they recover fully within a minute or two. Call 999 if they do not, if they are injured, if they have chest pain, or if breathing is abnormal.

Get an ECG. It is quick, cheap, and it is what separates the harmless from the dangerous.

For recurrent ordinary faints, teach the warning signs and the counter-manoeuvres: sit or lie at the first symptom, cross the legs and tense them, clench the fists and tense the arms.

Increase fluids and salt if advised, and stand up in stages.

Review the medicines of any older person who has fainted, including the ones bought over the counter.

Report to the DVLA where the rules require it, and ask what those rules are rather than guessing.

Where to get help

A GP practice for the first faint, asking specifically for an ECG.

Urgent assessment for fainting on exertion, fainting while lying down, or fainting with no warning.

999 if the person does not recover fully, has chest pain, or is injured.

Arrhythmia Alliance have clear information on blackouts and heart rhythm causes.