Moisture is a theoretical concept of Chinese medicine. Wet as water is yin evil. Wet, heavy, turbid, greasy, stagnant, easy to hurt Yang Qi. Wet and sticky, such as loose stool, uncomfortable and sticky stool, or white mucus, which has a long course of disease and is difficult to heal, such as wet arthralgia and eczema. Dampness is a kind of disease, which comes from external factors and is different from the body itself, that is, there are internal dampness and external dampness. External dampness is caused by three factors: rain and dew, wet water and sweating.

Internal dampness is caused by two factors: diet, wine and cheese, spleen and renal failure. Therefore, the pathogenesis of external dampness is related to the climate and environment, or the spleen and stomach are weak and susceptible to external dampness, but every time it is combined with wind, cold and heat, it is a disease. The disease often invades from the body surface, gradually reaching the skin, meat, bones and muscles, and going deep into the viscera. However, internal dampness is a pathological product. Although its etiology is caused by diet, cheese, fatigue, internal injuries and other factors, pathologically speaking, all zang-fu organs are autogenous, that is, the deficiency of qi and blood in zang-fu organs is the root cause of internal dampness.