What to notice
- Whether the heartbeat feels fast, pounding, fluttering or irregular
- How suddenly the palpitations start and stop
- How long each episode lasts and how often it happens
- Whether it occurs at rest, during exercise or after caffeine
- Whether any medicines or supplements recently changed
- Whether there is dizziness, shortness of breath, chest discomfort or fainting
Common cause groups
Everyday triggers
Exercise, stress, lack of sleep and other temporary changes can sometimes make the heartbeat feel faster or more noticeable.
Caffeine and medicines
Caffeine and some medicines can increase heart rate or make palpitations more noticeable in some people.
Blood or thyroid-related causes
Anaemia and thyroid conditions such as an overactive thyroid can sometimes cause a fast heartbeat or palpitations together with other symptoms.
Heart rhythm-related causes
Some changes in heart rhythm can cause racing, pounding, fluttering or irregular sensations and may need further assessment when episodes keep recurring.
Associated signs
Dizziness
Shortness of breath
Chest pain or discomfort
Fainting or near-fainting
Fatigue or weakness
Trembling or shakiness
How it may be assessed
A doctor will usually ask what the palpitations feel like, when they occur, how long they last and whether there are obvious triggers or other symptoms. Blood pressure and pulse may be checked first. Depending on the pattern, selected blood, thyroid or heart-rhythm tests may then be considered.
Assessment and investigations
Blood Pressure
Blood pressure and pulse are useful basic measurements when recurrent palpitations or a fast heartbeat are being assessed.
Thyroid Function
Thyroid testing may be considered when palpitations occur with symptoms such as tremor, heat intolerance, unexplained weight change or persistent fast heartbeat.
Full Blood Examination
A blood count may help identify anaemia when palpitations occur together with fatigue, dizziness or shortness of breath. Iron studies may be considered separately when iron deficiency is relevant.
When to get checked
Consider medical assessment if palpitations keep returning, last longer than usual, are becoming more frequent, occur without an obvious trigger, or happen together with dizziness, breathlessness or reduced ability to exercise normally.
Urgent warning signs
Seek prompt medical care if palpitations occur with chest pain, fainting or significant shortness of breath.
Frequently asked questions
What causes heart palpitations?
Heart palpitations can occur with everyday triggers such as exercise, stress or caffeine, as well as some medicines and health conditions including anaemia, thyroid problems or changes in heart rhythm.
Why does my heart suddenly start racing?
A fast heartbeat can happen for several reasons, including exercise, stress, caffeine, medicines and some medical conditions. Recurrent episodes are best considered together with how long they last and whether other symptoms occur.
Can an ECG detect the cause of heart palpitations?
An ECG can record the heart's rhythm and may help identify some rhythm problems. However, palpitations that come and go may not occur during a resting ECG, so a normal result does not always explain intermittent symptoms.
Screening context
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