Tachycardia
A resting heart rate above 100 beats per minute in an adult.
What it means
Tachycardia is a heart rate exceeding 100 beats per minute in a resting adult. From the Greek tachys, swift, and kardia, heart.
It is frequently an appropriate physiological response rather than a disorder of the heart itself. Exercise, fever, pain, anxiety, dehydration, anaemia, an overactive thyroid, alcohol, caffeine and many medicines all raise the heart rate through normal mechanisms.
Where the rhythm itself is abnormal, tachycardias are classified by their origin:
- Sinus tachycardia — a normal rhythm at a fast rate
- Supraventricular tachycardia — arising above the ventricles
- Atrial fibrillation — irregular and disorganised atrial activity
- Ventricular tachycardia — arising in the ventricles, and potentially life-threatening
In practice
Recorded in observations alongside blood pressure, temperature and respiratory rate, and characterised on an electrocardiogram, which distinguishes the underlying rhythm.
The opposite term is bradycardia.
Why it matters
The clinical importance lies in the rhythm and the context rather than the number alone. A well person with a rate of 110 during a fever is behaving normally; the same rate at rest without explanation is not.
Tachycardia accompanied by chest pain, breathlessness, fainting or collapse requires emergency assessment. A persistently irregular fast pulse raises the possibility of atrial fibrillation, which substantially increases stroke risk and is treatable once identified.
Clinically reviewed by Dr Mohammad Zubair Khan, GMC 7563469
Last reviewed
August 30, 2026