Abstract
External pathogens such as wind, cold can easily invade the external parts of the body when host's external defense ability is not secure. Herein, we consider the underlying mechanisms against the external contraction at the body surface. During the early period after primary invasion, external defense mechanisms are gradually activated. The classic clinical manifestations are aversion to cold, fever, headache, generalized pain, and nasal congestion. This condition is called by invasion of external pathogen into the body surface. As the disease progress, lung qi is stagnated and thereby up-outward and downward movement action of lung become disturbed. Therefore, when doctor administrate formula to treat the exterior syndrome, doctor must keep in mind not only materia medica, but also underlying mechanisms through which many clinical symptoms appear.
