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 and low blood pressure. If you have cough and are taking medicines that contain asthalin or terbutaline then the palpitations can be a side effect of the drugs.
Hope this helps.