Sudden Heart Palpitations: When Is It an Emergency?

Short answer: Palpitations can follow common triggers such as poor sleep, exercise, stress or caffeine, but the sensation alone cannot tell you whether the rhythm is dangerous. If palpitations are happening now and do not settle, or occur with chest pain, shortness of breath, severe dizziness, near-fainting, fainting or loss of consciousness, use emergency services now. In Korea call 119; elsewhere call your local emergency number.

Who is this for?

This general guide is for adults who notice a new racing, fluttering, pounding, skipped or irregular heartbeat in the chest, neck or throat. Episodes may last seconds, minutes or longer. Exercise, lack of sleep, stress, caffeine, alcohol, nicotine and some medicines can trigger palpitations. Other possibilities include anemia, an overactive thyroid, dehydration, electrolyte problems, heart disease or an arrhythmia.

Pregnancy, known heart disease, or a close family history of sudden death at a young age or inherited rhythm disease may lower the threshold for prompt assessment. Do not stop a prescription medicine on your own. Bring a complete list of prescriptions, over-the-counter cold medicines, inhalers, weight-loss products and supplements to the visit.

Which warning signs need emergency care?

  • Chest pain or pressure, especially pain spreading to an arm, the back, neck or jaw
  • Shortness of breath or difficulty breathing
  • Severe dizziness, feeling about to faint, fainting or reduced alertness
  • Unusual sweating, sudden confusion or marked pallor
  • Palpitations that do not go away while any of the symptoms above are present

Do not delay emergency care to repeat pulse checks or finish a smartwatch recording. Do not drive yourself when emergency transport is appropriate. If the episode has stopped but included chest pain, breathlessness or fainting, contact an urgent medical service promptly to determine when you should be assessed.

What if there are no emergency warning signs?

Arrange a clinical review if the episodes keep returning, are becoming more frequent, last more than a few minutes, or are new and unrelated to exercise. The Korean Disease Control and Prevention Agency notes that the circumstances in which symptoms start or worsen, associated symptoms, medical history and medicines are central to the evaluation. A 12-lead electrocardiogram (ECG) is a key test. Depending on the history, clinicians may also check a blood count, electrolytes, thyroid function or other possible causes.

An office ECG shows the rhythm during the recording, so it can be normal between intermittent episodes. A clinician may choose a Holter monitor or a longer event monitor based on how often symptoms occur. A smartwatch heart-rate or rhythm alert can be useful context, but it cannot by itself confirm or rule out an arrhythmia.

What should you record?

  • Date and time, duration, and whether the episode started and stopped suddenly or gradually
  • Heart rate, if safely available, and whether the pulse felt regular or irregular
  • Exercise, sleep loss, stress, caffeine or energy drinks, alcohol and nicotine before the episode
  • Chest pain, breathlessness, dizziness, fainting or sweating
  • Names and doses of medicines and supplements, including recent starts or dose changes
  • A wearable tracing or screenshot that matches the symptom time, only if collecting it does not delay urgent care

Questions to ask at a visit

  • Does this pattern need a Holter monitor or longer rhythm monitoring in addition to an ECG?
  • Should anemia, thyroid disease or electrolyte problems be checked?
  • Could any of my prescriptions, cold medicines, stimulants or supplements contribute?
  • If this happens again, which symptoms or duration should trigger emergency care?

Related resources

Sources and review date

Reviewed: October 6, 2026

This is general health information, not personal diagnosis or treatment advice. Decisions can differ with symptoms and risk factors.