The difference between Heart Yang and Heart Fire is mainly that Heart Yang is a physiological state and Heart Fire is a pathological state. Heart yang is the embodiment of heart qi, which has the function of warming the blood and promoting blood circulation. Heart qi is divided into heart yin and heart yang. Heart yang is a state that manifests warmth and activity. Heart yang deficiency is characterized by cold sweating, lack of warmth in the limbs, fear of cold, depression, and a weak pulse. Heart fire, on the other hand, is caused by various reasons that lead to over-exuberance of heart yang and transforms it into fire, which often manifests as sores on the mouth and tongue, irritability, toothache, and insomnia. A common cause of Heart Fire being over-exuberant is heart-kidney disharmony (heart fire, kidney yin deficiency, dysfunction of the physiological functions of the heart and kidneys). Heart yang does not descend to warm the kidneys, and kidney yin does not nourish heart yin. If uncomfortable symptoms occur, it is recommended to consult a medical professional for evidence-based treatment.