EmergencyEmergency Guide
Rapid heartbeat: Red Flags & Emergency Signs
A heart rate above 150 bpm at rest, or any tachycardia with haemodynamic instability (low BP, collapse, breathlessness) is a cardiac emergency requiring immediate 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
- ⚠Heart rate >150 bpm with chest pain or breathlessness — ventricular tachycardia or PE
- ⚠Rapid heartbeat with hypotension or collapse — haemodynamically unstable arrhythmia
- ⚠Sudden racing heart with loss of consciousness — VT or VF
- ⚠Rapid heart rate in sepsis with confusion and low BP — septic shock
- ⚠Rapid heartbeat with anaphylaxis symptoms (rash, throat tightness) — anaphylactic shock
⚡ See a Doctor Today
- •New rapid heartbeat with breathlessness and leg swelling — PE or heart failure
- •Rapid heartbeat with fever and murmur in an IV drug user — endocarditis
- •Rapid heartbeat with weight loss, tremor, and heat intolerance — thyrotoxicosis
High-Risk Combinations
When rapid heartbeat occurs together with any of these symptoms, urgency increases significantly:
Conditions to Rule Out Urgently
Ventricular Tachycardiaemergency
12-lead ECG; DC cardioversion if unstable
Pulmonary Embolismemergency
Sinus tachycardia + S1Q3T3 on ECG; CTPA
Sepsisemergency
Sepsis-3; IV fluids + antibiotics + source control
Anaphylaxisemergency
IM adrenaline 0.5mg; 999
Cardiac Tamponadeemergency
Pulsus paradoxus; echo; pericardiocentesis
Condition Authority Pages
When to Call Emergency Services
- →Heart rate felt racing with chest pain, breathlessness, or near-collapse
- →Rate above 150 bpm at rest with dizziness
- →Sudden onset very fast heartbeat from which you cannot recover with rest