Heart palpitations can feel like your heart is:

• Skipping beats
• Fluttering rapidly
• Beating too fast
• Pounding
• Flip-flopping

You might feel heart palpitations in your throat or neck, as well as your chest. They can occur when you're active or at rest.

Often the cause of your heart palpitations can't be found. Common causes include:

• Strong emotional responses, such as stress, anxiety or panic attacks
• Depression
• Strenuous exercise
• Stimulants, including caffeine, nicotine, cocaine, amphetamines, and cold and cough medications that contain pseudoephedrine
• Fever
• Hormone changes associated with menstruation, pregnancy or menopause
• Too much or to little thyroid hormone

Occasionally heart palpitations can be a sign of a serious problem, such as an overactive thyroid gland (hyperthyroidism) or an abnormal heart rhythm (arrhythmia). Arrhythmias might cause a very fast heart rate (tachycardia), an unusually slow heart rate (bradycardia) or an irregular heart rhythm.

You might be at risk of developing palpitations if you:

• Are highly stressed
• Have an anxiety disorder or have regular panic attacks
• Are pregnant
• Take medicines that contain stimulants, such as some cold or asthma medications
• Have an overactive thyroid gland (hyperthyroidism)
• Have other heart problems, such as an arrhythmia, heart defect, previous heart attack or previous heart surgery

Unless a heart condition is causing your heart palpitations, there's little risk of complications. For palpitations caused by a heart condition, possible complications include:

• Fainting. If your heart beats rapidly, your blood pressure can drop, causing you to faint. This might be more likely if you have a heart problem, such as congenital heart disease or certain valve problems.
• Cardiac arrest. Rarely, palpitations can be caused by life-threatening arrhythmias and can cause your heart to stop beating effectively.
• Stroke. If palpitations are due to a condition in which the upper chambers of the heart quiver instead of beating properly (atrial fibrillation), blood can pool and cause clots to form. If a clot breaks loose, it can block a brain artery, causing a stroke.
• Heart failure. This can result if your heart is pumping ineffectively for a prolonged period due to an arrhythmia, such as atrial fibrillation. Sometimes, controlling the rate of an arrhythmia that's causing heart failure can improve your heart's function.