Palpitations usually occur when something disrupts the normal electrical activity or function of the heart. They may be felt when the heart is beating quickly, slowly, or irregularly (an arrhythmia) or when the heart is contracting more forcefully than usual. Sometimes, palpitations occur for unknown reasons in people with no evidence of heart disease or arrhythmias.
Arrhythmias may occur in otherwise healthy individuals in response to lifestyle factors, prescription medications, or other drugs. In some individuals, arrhythmias occur due to an underlying condition or illness.
Lifestyle factors that can cause palpitations include:
Consuming too much of a caffeinated beverage (such as coffee, tea, cola) or other caffeine-containing product (such as chocolate)
Drinking too much alcohol
Stress or anxiety
Certain medications (such as diet pills or thyroid hormone replacement)
Certain over-the-counter medications (such as decongestants), certain diet supplements, and "recreational" drugs
Conditions that can cause palpitations include:
Serious illness or fever (which can increase the heart rate)
Nausea and vomiting (which can affect the nervous system and slow the heart rate)
Thyroid gland disease
Anemia (a condition in which your number of red blood cells is less than normal)