Red flag symptoms: Loss of consciousness

It is essential to elucidate any preceding symptoms.

Explore patient's fears about what happened (SPL)
Explore patient's fears about what happened (SPL)
  • Preceding chest pain
  • Preceding dyspnoea
  • Preceding headaches
  • Preceding palpitations
  • Preceding abdominal pain
  • Associated weakness of arm, face or leg
  • Associated with exercise or posture
  • Blood loss
  • Evidence of GI bleeding
  • Associated tongue biting, urinary incontinence or prolonged limb jerking

Taking a detailed history often leads to diagnosis of the cause of loss of consciousness without requiring further investigations. A collateral history will also be useful.

Patients have often researched their own symptoms, so it is important to find out why they have presented now and to establish their thoughts and fears about what happened and the possible diagnosis.

Explore the patient's agenda and if they have a plan in mind.

Key questions to ask

  • When did the episodes start?
  • What happens before the episodes occur?
  • In general, what is the patient doing when loss of consciousness occurs?
  • Does this happen in warm or crowded environments?
  • Do they have warning symptoms?
  • Is there any associated light-headedness, headaches, chest pain, palpitations, abdominal pain or shortness of breath?
  • Are the episodes ever witnessed? If so, what does the witness notice? Useful information may include the colour the patient goes before the event.
  • Is there any limb jerking during the event? If so, ask the patient to demonstrate it, if possible. How long does this last?
  • Does the patient report any tongue biting or urinary incontinence during the event?
  • How long does it take the patient to come round and how do they feel when they do?
  • Has the patient ever experienced these episodes before and if so, did they seek medical attention and receive a diagnosis?
  • Has there been any obvious GI bleeding?
  • Does the patient take any regular prescribed or non-prescribed medication?

Enquire about any family history of sudden death and complete the history by asking about smoking and alcohol consumption. Establish the patient's occupation.

It may be important to know if the patient drives, because their diagnosis may need to be reported to the DVLA.

Consider if any additional measures might be necessary to support the patient at home.


Important things to check will include BP and pulse. Check if the pulse rate is regular. Check lying and standing BP.

Auscultate the heart sounds, listening for any added sounds or murmurs.

A focused neurological examination may be necessary. Examine the pupils and their reaction to light and accommodation. You might also examine the fundi. Palpate for the aorta if indicated.

Possible investigations

  • Blood tests, including FBC, U&Es, ferritin, HbA1c
  • BP
  • ECG
  • Echocardiogram
  • Gastroscopy
  • Colonoscopy
  • Abdominal ultrasound scan

When to refer

If the patient is acutely unwell or a life-threatening emergency is suspected, you will need to admit them directly to hospital.

Refer to neurology if a diagnosis of epilepsy is suspected. The patient may require a CT head and EEG.

Refer to falls clinic if the diagnosis is unclear and the patient is having recurrent episodes.

Discovery of iron deficiency anaemia may require referral to your local iron deficiency anaemia clinic, depending on local policy.

A diagnosis of abdominal aortic aneurysm (AAA) will require urgent referral to a vascular surgeon, depending on the size of the AAA.

Detection of arrhythmia, heart block or cardiomyopathy will require assessment by a cardiologist.

Regarding the patient's fitness to drive, refer to DVLA guidance if the diagnosis is unclear and the symptoms are still occurring.

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  • Dr Singh is a GP in Northumberland

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