Other than this there are many medical causes of feeling your heart
race or palpitations
may be normally felt if you are overexerted. Chemicals like adrenaline, alcohol, caffeine, cocaine, amphetamines, and other drugs all cause palpitations. Disease (such as hyperthyroidism and pheochromocytoma) or mitral stenosis, panic disorder all cause this. Palpitations may be associated with heart problems, anemias, low blood sugar and low blood pressure.