The infantile constant insufficiency of the spleen and weakness and small size of the stomach make it impossible to contain more food. Attack by exogenous pathogenic factors, together with the weakness of the spleen and stomach causes dysfunction in transportation and transformation, and further leads to excessive dampness in large intestine, finally giving rise to frequent watery diarrhea; improper feeding, excessive intake of raw and cold, or heavy food impair the spleen and stomach, causing the obstruction of ingestion and transportation as well as dysfunction in ascending and descending.

In this case, the spleen fails to send food essence upward to the lung, resulting in diarrhea; constant asthenia of the spleen and stomach causes disturbance of sending food essence upwards and the digested food downwards. In this case, food stuff stagnates and the purity and turbidity enter the large intestine together, bringing about diarrhea; chronic impairment involving the kidney, or splenic yang deficiency in the case of constant asthenia of the spleen and kidney makes the spleen unable to promote water metabolism while nephric yang deficiency makes the spleen lose its warming function and unable to digest food, giving rise to diarrhea due to asthenic cold.