Palpitations are feelings that your heart is skipping a beat, fluttering, or beating too hard or too fast. You may have these feelings in your chest, throat, or neck. They can occur during activity or even when you're sitting still or lying down. Many things can trigger palpitations, including:
-- Strong emotions
-- Vigorous physical activity
-- Medicines such as diet pills and decongestants
-- Caffeine, alcohol, nicotine, and illegal drugs
-- Certain medical conditions, such as thyroid disease or Anemia
 
These factors can make the heart beat faster or stronger than usual, or they can cause premature (extra) heartbeats. In these situations, the heart is still working normally. Thus, these palpitations usually are harmless.

Some palpitations are symptoms of arrhythmias. Arrhythmias are problems with the rate or rhythm of the heartbeat. Some arrhythmias are signs of heart conditions, such as heart attack, heart failure, heart valve disease, or heart muscle disease. However, less than half of the people who have palpitations have arrhythmias. You can take steps to reduce or prevent palpitations. Try to avoid things that trigger them (such as stress and stimulants) and treat related medical conditions.

What should I do if I have palpitations?
Occasionally, palpitations can be serious. In the following situations, you should call an ambulance:
If you have palpitations that do not go away quickly (within a few minutes).
If you have any chest pain with palpitations.
If you have severe breathlessness with palpitations.
If you pass out, or feel as if you are going to pass out, or feel dizzy.
If you have palpitations and have had heart problems in the past.
If you have palpitations which began as you were exercising.

If the palpitations do not make you feel unwell, and settle on their own, you should see your GP. Keep a diary of when they happen and how long they last, as this information will help your GP.