Pathogenic cold is prevalent in winter and as a yin pathogenic factor,
it is likely to consume yang qi. It also has the characteristics of
contracture and stagnation. These are described as follows:
Pathogenic cold, as a Yin Pathogenic Factor
Pathogenic cold is liable to consume the yang qi of the body, producing cold syndromes. If the pathogenic cold attacks the body surface leading to a closing of the pores and obstruction of the flow of defensive yang qi, it is manifested by the symptom of aversion to cold. If pathogenic cold directly attacks the spleen and stomach it leads to the injury of spleen yang qi causing dysfunctions of the whole digestive process. The clinical manifestations are vomiting of clear water, diarrhea, coldness and pain of the epigastric and abdominal regions, pain relieved by warmth and aggravated by cold extremities, etc.
Pathogenic cold is characterized by Contracture and Stagnation
Invasion of pathogenic cold may cause contracture of the blood vessels and tendons, and obstruction of qi and blood circulation. This manifests as pain of a cold nature. Pathogenic cold may also cause a common cold with symptoms of sore aching joints and headache. Stagnation of cold in the liver channel leads to hernia of a cold nature, coldness, pain, and swelling of the testis. Pathogenic cold may also cause stomach ache, abdominal pain, etc.
Commonly seen syndromes caused by exogenous pathogenic cold are classified into: cold damaging the skin and muscle and cold damaging the spleen and stomach.
Cold Damaging the Skin and Muscle: fever, aversion to cold, no sweating, tense and superficial pulse, cough, asthma, nasal obstruction, nasal discharge, headache, and aching body.
Fever, aversion to cold, no sweating, tense and superficial pulse are caused by exogenous pathogenic cold that has blocked the spreading of wei (defensive) qi. The lung is closely related to the skin and hair. If exogenous pathogenic cold blocks the body surface and the wei qi can not spread, then lung qi fails to disperse and descend, causing nasal obstruction and discharge, cough, and asthma. Exogenous pathogenic cold will also obstruct the channels, resulting in the stagnation of qi and blood, which manifests as headache and aching body.
Exogenous Pathogenic Cold Injuring the Spleen and Stomach: vomiting, diarrhea, borborygmus, and abdominal pain.
This group of symptoms is caused by an over-intake of raw and cold food or the exposure of the abdomen to cold. As exogenous pathogenic cold injures the yang qi of the spleen and stomach, then the functions of ascending and descending qi by the spleen and stomach become disordered, causing a dysfunction of digestion and absorption with the symptoms of vomiting, diarrhea, abdominal pain, borborygmus, etc.
More about the other Exogenous Factors:
Fire Heat and Mild Heat.