EmergencyEmergency Guide
Loss of consciousness: Red Flags & Emergency Signs
Loss of consciousness (syncope or collapse) ranges from benign vasovagal episodes to cardiac arrest — any unexplained episode requires urgent cardiac and neurological assessment.
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If you have this symptom right now
Call 999 (UK) / 112 (EU) / 911 (US) immediately if any emergency warning signs are present. Do not drive yourself. Do not wait to see if it improves.
🚨 Call 999 / 112 Immediately
- ⚠Collapse without pulse or breathing — cardiac arrest, begin CPR immediately
- ⚠Collapse with chest pain before losing consciousness — cardiac cause
- ⚠Collapse during exercise (especially in young person) — arrhythmia or hypertrophic cardiomyopathy
- ⚠Collapse with tongue biting, urinary incontinence, and prolonged confusion — seizure (status epilepticus risk)
- ⚠Collapse with neurological deficit on recovery — TIA or posterior circulation stroke
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- •Any first-ever episode of loss of consciousness requires same-day ECG and assessment
- •Recurrent collapses without clear vasovagal trigger
- •Collapse in a patient on QT-prolonging medications
- •Collapse with palpitations immediately beforehand
High-Risk Combinations
When loss of consciousness occurs together with any of these symptoms, urgency increases significantly:
Conditions to Rule Out Urgently
Ventricular Tachycardia / Fibrillationemergency
ECG; Holter monitor; ICD consideration
12-lead ECG; 24-hour Holter
Hypoglycaemiaemergency
Blood glucose immediately; treat with dextrose
Acute MIemergency
Troponin + ECG in all unexplained collapses
Massive PEemergency
D-dimer; CTPA; thrombolysis if haemodynamically compromised
Epileptic Seizureurgent
EEG; MRI brain; driving restrictions apply
Condition Authority Pages
When to Call Emergency Services
- →Any collapse with no pulse — begin CPR
- →Collapse during exercise in a young person
- →No recovery of consciousness within 2 minutes
- →Collapse with chest pain, breathlessness, or facial droop