Cough is mainly caused by exogenous pathogenic factors and the disorder is usually located in the lung and spleen. Since the infantile viscera are delicate and the exterior defending function is not strong enough, the infants are subject to the invasion of exogenous pathogenic factors, the leading one among which is the pathogenic wind which is the major cause of many diseases. It also may be caused by invasion of accompanied cold or heat into the body, directly attacking the lung. Invasion of pathogenic factors into the lung will inevitably affect the normal dispersion and descent functions of the lung, resulting in upper adverse flow of the pulmonary qi which causes cough.

Since the infants are insufficient in the spleen qi, they are liable to be affected by milk feeding and cold food which injure the normal transforming and transporting functions of the spleen, leading to retention of dampness which is further coagulated into phlegm. The storage of phlegm in the lung will obstruct respiratory tract and stagnate the pulmonary qi, consequently causing cough. Prolonged cough will, in turn, consume qi and yin, bringing about such syndromes as deficiency of pulmonary yin or deficiency of pulmonosplenic qi.