A fast pulse is a finding rather than a diagnosis. It can be an appropriate sinus response to exercise, fever or stress, or an arrhythmia requiring specific assessment.
Why the Symptom Pattern Matters
- Gradual acceleration and slowing often suggests sinus tachycardia.
- Sudden onset and termination may suggest SVT.
- Irregular rapid pulse may occur with atrial fibrillation.
- A wide-complex rapid rhythm is treated cautiously until ventricular tachycardia is excluded.
Possible Causes
This list explains possibilities; the symptom alone cannot establish a diagnosis.
- Exercise, fever, pain, dehydration or anxiety
- Anaemia, thyroid disease or infection
- SVT, atrial fibrillation or flutter
- Ventricular tachycardia
- Stimulants and medicines
What the Clinician Will Assess
- Onset, regularity, duration and triggers
- Chest pain, breathlessness, fainting and circulation
- ECG during the episode
- Structural disease and family history
Which Tests May Be Considered?
Not every test is required for every person. Selection depends on examination findings and clinical probability.
- 12-lead ECG
- Rhythm monitoring
- Blood count, thyroid and electrolytes
- Echocardiography when indicated
What to Record Before the Appointment
- Pulse rate and regularity
- Start-stop pattern
- Temperature, hydration, stimulant and medicine exposure
- Wearable trace when safe
When to Call Emergency Services
Do not wait for an online reply
- Fast rhythm with fainting, severe chest pain or breathlessness
- Low blood pressure, confusion or cold clammy skin
- Sustained wide-complex rhythm
- New neurological symptoms
Frequently Asked Questions
Is 100 beats per minute always dangerous?
No. Rate, context, duration, symptoms and rhythm mechanism matter.
Can dehydration cause tachycardia?
Yes, but persistent or severe symptoms still require assessment.
Can I exercise through it?
Stop if the rhythm is unexplained or accompanied by warning symptoms.
Medical information note
This page provides general information and does not replace examination, diagnosis or an individual treatment plan.