Damp is the main pathogenic factor causing disease in the late summer
since it is the most humid and rainy season. It is a yin pathogenic
factor with the following characteristics:
Pathogenic damp stops the functional activity of qi and leads to the injury of spleen yang
The spleen functions best in a dry environment and is susceptible to dampness, therefore pathogenic damp is liable to attack spleen yang. If spleen yang is checked by pathogenic damp, it will cause a dysfunction of transportation and transformation, and obstruct the functional activity of qi. The following symptoms will occur: distension and fullness of the epigastric and abdominal regions, anorexia, sweetish taste in the mouth, loose stool, cold extremities, etc.
Pathogenic damp is a substantial pathogenic factor characterized by heaviness, turbidity, viscosity, stagnation, and sluggishness
Invasion by pathogenic damp also causes the symptoms of heaviness, distension and soreness of the trunk and extremities. The secretions and excretions of the patient has foul and turbid features. The disease duration lingers.
Pathogenic damp is characterized by a downward direction.
It is a yin pathogenic factor which often attacks the lower portion of the body. The Suwen says, "When damp attacks the body, it will affect the lower portion first."6 Clinical manifestations are ulceration and edema of the lower extremities, soreness of muscles, and joint pain of the lower limbs, etc.
Commonly seen syndromes caused by pathogenic damp are exterior damp, and damp bi.
Main clinical manifestations of exterior damp: fever, aversion to cold, fever not lowered after sweating, heaviness of the body and head, sore aching of the four limbs, white, thin and slippery tongue coating, soft and slow pulse.
Those symptoms are due to the injury of the body surface by pathogenic damp. When there is obstruction by dampness, it damages the yang qi of the body, and blocks the defensive qi. So fever and aversion to cold appear. Damp is characterized by heaviness, turbidity, and stickiness. Thus fever is not lowered after sweating. Moreover, other manifestations such as heaviness of the body and head, sore aching of the four limbs, slippery tongue coating, and soft pulse occur.
Damp bi is one of the bi syndromes due to excessive pathogenic damp, also known as fixed by syndrome.
Manifestations of damp bi: continued soreness at one location, aching and heaviness of the joints, motor impairment, and numbness of the skin.
Bi syndromes indicate the obstruction by wind, cold, or damp in the channels which damages the joints, skin, and muscles. Damp is characterized by heaviness and turbidity, so heaviness is fixed in the joints.
More about the other Exogenous Factors:
Fire Heat and Mild Heat.