The changes of the Six Climatic Factors in nature are extremely complex and often abnormal. Therefore, in the diseases caused by the Six Climatic Factors, it is more common for two or more types of pathogenic qi to combine and cause illness. The Six Climatic Factors also influence each other and can transform into one another under certain conditions, known as the Six Climatic Factors transformation in accord with constitution. The trend of transformation when the Six Climatic Factors harm the human body is closely related to the relative excess or deficiency of the yin-yang qi in the body. In individuals with yang exuberance or yin deficiency, external pathogens are prone to transform into heat and dryness; in those with yang deficiency or yin exuberance, external pathogens are more likely to transform into cold. The same pathogenic qi invading the human body can lead to different pathological changes depending on the individual, with variations in transforming into cold or heat. The relative excess or deficiency of water and fire in the body is the key factor determining the transformation of pathogenic qi according to its nature. Below, we discuss the common mechanisms of disease involving the combination and transformation of the Six Climatic Factors in accord with constitution.
(1) Wind-cold combination and wind transforming into cold Wind is the dominant qi of spring, while cold is the dominant qi of winter. How can they combine? This is because wind is the leader of all diseases and is present throughout the seasons, thus it can combine with other qi to cause illness. Climatic changes can sometimes be abnormal, such as when spring should be warm but cold persists, known as untimely qi, or when residual cold remains in early spring. In such cases, wind and cold can combine to cause illness, often resulting in wind-cold double invasion. The mechanism of disease is characterized by wind-cold attacking externally, leading to the stagnation of defensive yang, impaired lung diffusion and descent, and obstruction of the upper orifices. As for wind transforming into cold, this is a form of transformation in wind qi-related diseases. The mechanism of disease typically occurs in individuals with inherent yang weakness and internal cold, especially when exposed to wind in winter, leading to a combination of external and internal cold that promotes the transformation of wind into cold. Refer to the previous section on the "mechanism of disease of cold qi."
(2) Wind-heat combination and wind transforming into heat In spring, wind qi dominates, and the qi is already warm. However, if it becomes excessively hot, this is considered untimely qi. At this time, wind is often combined with heat, and if a person is affected by it, they will suffer from wind-heat. The mechanism of disease is characterized by external wind-heat invasion, leading to the impairment of defense qi, impaired lung diffusion and descent, and a tendency to transform into dryness, damaging yin and disturbing the seven orifices. Wind transforming into heat is another form of transformation in wind qi-related diseases. The mechanism of disease typically occurs in individuals with inherent yang exuberance and yin deficiency, especially when exposed to wind in late spring or during winter when warmth replaces cold. In such cases, the external climatic heat and the internal yang exuberance promote the transformation of wind into heat.(3) Wind-dampness combination and cold transformation During the long summer, excessive rain and damp climates often cause wind to combine with dampness. Alternatively, living in low-lying, damp environments, or sweating and being exposed to wind while wearing damp clothes, can also lead to wind-dampness combination, which can invade the body and cause wind-dampness illness. The mechanism of disease involves the combination and struggle of wind and dampness, often with wind harming the defensive qi and dampness lingering in the joints. When wind-dampness combines and invades the body, it can persist internally. Depending on the constitution's abnormal exuberance of yin or yang deficiency, external climatic conditions of cold or heat, and dietary or medicinal influences of warmth or coolness, wind can transform into cold or heat. Wind-dampness transforming into cold often occurs in individuals with inherent yang weakness and yin exuberance, or during winter when cold qi is dominant; or due to excessive consumption of raw and cold foods, damaging spleen and stomach yang; or inappropriate medical treatment with excessive use of cold and cool herbs. Wind-dampness transforming into cold can result in the combined pathogens of wind, cold, and dampness, which may stagnate in the meridians or obstruct the spleen and stomach, leading to various corresponding mechanisms of disease.
(4) The combination of cold-dampness and the transformation of cold-dampness into heat. If one is exposed to fog and dew for a long time, in a damp environment, and then catches a cold pathogen, or if a body with yin exuberance is injured by dampness and the dampness transforms into cold; or if one indulges in raw and cold foods, or uses excessively cold and cool medicines, injuring the middle yang and causing internal dampness to grow, which then transforms into cold, all these reasons can lead to the formation of a disease combining cold and dampness. The mechanism of disease changes, first, is the external exposure to cold-dampness, injuring the muscles, bones, and joints; second, is the prolonged retention of cold-dampness, injuring the spleen and kidney yang qi. The mechanism of disease changes for the transformation of cold-dampness into heat mainly occurs in two situations: one is the prolonged retention of cold-dampness, staying and not leaving, stagnating and transforming into heat over time; the other is the treatment of cold-dampness, long-term use of strong and drying agents, excessive use of pungent and hot substances, promoting the transformation of cold-dampness into heat. Generally speaking, the heat transformed from cold-dampness is mostly localized and temporary, and it is rare for cold-dampness to transform into purely fiery heat pathology. The localization refers to the heat that is transformed, mainly appearing as local heat signs on the basis of cold-dampness disease, rather than completely transforming into fiery heat. The temporariness refers to the local heat transformation of cold-dampness, which does not last long and is eliminated under certain conditions. The pathological manifestations of cold-dampness transforming into heat include redness, swelling, heat, and pain in local joints, or on the basis of the pattern of cold dampness, symptoms such as dry mouth and desire to drink, dry and sore throat, hot and yellow urine, dry and hard stools, red tongue with little fluid, and rapid pulse may appear.(5) Dampness-heat combined with transformation into fire and dryness. In late summer and early autumn, the rainy season is prolonged, with heat from above and dampness rising from below. Dampness-heat yin qi and yang qi meet together, combining to cause harm, often invading the body through the mouth, nose, or skin. Those with a naturally strong yang constitution may experience dampness transforming into heat, or prolonged dampness may accumulate and generate heat. Overuse of warm and hot medications can also cause dampness to transform into dryness and heat, leading to dampness-heat combined diseases. The mechanisms of disease transformation include: (1) Dampness, as a yin pathogen, is sticky and insidious, making the onset subtle and the condition lingering. (2) During the course of the disease, it often obstructs the spleen and stomach. (3) There are different manifestations depending on whether dampness or heat predominates. When dampness predominates, symptoms may include low-grade fever that persists, worsening in the evening, mental fatigue, drowsiness, chest and abdominal distension, and thirst without desire to drink. When heat predominates, symptoms may include persistent fever, sweating without relief, dysphoria, bitter taste in the mouth, and foul breath. If dampness-heat rises and obstructs lung qi, it may cause coughing or wheezing. If it clouds the pericardium, it may lead to mental confusion, alternating between clarity and cloudiness. If dampness-heat pours downward, disrupting bladder qi transformation, it may cause painful urination or ischuria. If it affects the large intestine's conduction, it may lead to constipation or diarrhea. If dampness-heat steams the liver and gallbladder, impairing their function, gall may overflow into the skin, causing jaundice. The mechanisms of dampness-heat transforming into fire and dryness include: (1) Pathogenic heat predominating in dampness-heat, combined with a naturally strong yang constitution or excessive use of heat-inducing treatments, leading to transformation into fire and dryness. (2) General dampness-heat obstructing the spleen and stomach, or internal dampness-heat syndromes transforming into fire and dryness, with disease mechanisms similar to those of fire and dryness qi. If dampness-heat combines with warm pathogens to transform into fire and dryness, it may penetrate deeply into nutrient-blood, invade the pericardium, stir liver wind, or injure intestinal collaterals, causing bloody stools, with the most rapid pathological progression.(6) Summerheat-dampness with filth. Summerheat-dampness with filth often occurs between summer and autumn, due to the combined steaming of summer heat and earth dampness, mixed with filthy turbidity. When contracted, it enters through the mouth and nose, directly attacking the membrane source. The mechanisms of disease transformation include: (1) Summerheat-dampness with filth suddenly attacking the spleen and stomach, obstructing the middle, and hindering qi movement, leading to symptoms such as chest and epigastric stuffiness, dysphoria, nausea, and vomiting. (2) Summerheat-dampness internally accumulating, depressing clear yang, or clouding the seven orifices, leading to symptoms such as unconsciousness and deafness. (3) Summerheat-dampness with filth may lean more toward summerheat or dampness, with summerheat predominating causing high fever, and dampness predominating causing heavy filthy turbidity.
(7) Summerheat combined with cold-dampness. This often results from exposure to summer heat followed by cooling and consuming cold, leading to invasion by cold pathogens. The main mechanism of disease transformation is summerheat being internally depressed by cold-dampness, causing summerheat-dampness to obstruct the middle energizer, while cold binds the exterior, leading to symptoms such as headache, chills, fever, absence of sweating, epigastric stuffiness, diarrhea, and irritability.
(8) Cold-heat combined and transformation according to constitution. This often occurs when pathogenic heat lingers and is then affected by cold, or when a cold syndrome is followed by pathogenic heat. Under certain conditions, cold and heat can transform into each other, leading to cold-heat combined disease mechanisms. These can be divided into four pathological transformations: upper heat and lower cold, upper cold and lower heat, exterior cold and interior heat, and exterior heat and interior cold.
The pathological changes of upper heat and lower cold are often caused by the complexity of cold and heat in disease etiology. Pathologically, the qi of yin and yang cannot coordinate, leading to yang exuberance in the upper and yin exuberance in the lower, resulting in heat in the upper and cold in the lower. Symptoms include red eyes, dry nose, sore throat, bitter taste, chest heat, frequent vomiting, and other upper heat symptoms, as well as abdominal pain that prefers warmth, loose stools, clear and long urination, and cold lower limbs indicating lower cold symptoms. The pathological changes of upper cold and lower heat are mainly due to Hanrebing pathogens, which attack simultaneously or alternately, causing the upper and lower yin-yang to become disordered, with yin exuberance in the upper and yang exuberance in the lower, manifesting as cold in the upper and heat in the lower. Symptoms include cold chest and back, or cold pain in the chest and wrist, preference for warmth and fear of cold, indigestion, vomiting clear water, foul belching, and other upper cold symptoms, as well as red, swollen, hot, and painful lower limbs, severe constipation or loose stools with burning anus, and difficult urination indicating lower heat symptoms. The mechanism of disease changes in exterior cold and interior heat often occurs when there is pre-existing internal heat and external cold, or when external pathogens transform into heat while the exterior cold remains unresolved, characterized by the coexistence of external cold constricting the surface and pathogenic heat stagnating internally. The mechanism of disease changes in exterior heat and interior cold often occurs in individuals with pre-existing interior cold who are then affected by external heat, or when external contraction of wind-heat has not yet dissipated and is further complicated by excessive use of cold and cooling agents that injure the spleen and stomach yang qi, characterized by the coexistence of external contraction of wind-heat and pudendal coldness internally.
Regarding the transformation of cold and heat in accordance with constitution, during the course of illness, it is mainly determined by the contrast between pathogenic and healthy qi. It can manifest as cold transforming into heat or heat transforming into cold. The mechanism of cold transforming into heat is characterized by robust healthy qi, inherently vigorous yang qi, and exposure to cold pathogens that stagnate and eventually transform into heat. Alternatively, when cold pathogens cause illness, and healthy qi gradually recovers, excessive yang recovery can also promote the transformation of cold into heat. The transformation of cold into heat, i.e., from yin to yang, generally indicates a favorable turn in the disease mechanism. As for heat transforming into cold, its pathological evolution often results from inherently weak yang, excessive use of cold and cooling agents, or improper application of sweating, vomiting, or purgative methods, leading to further damage to yang qi. Heat transforming into cold can occur gradually or suddenly. For example, in cases of warm disease with high fever, excessive sweating leads to yang depletion, or severe vomiting and diarrhea cause qi collapse, resulting in cold limbs, pale complexion, restlessness, and deep, slow pulse. This is an example of sudden heat transforming into cold. In other cases, during the process of heat transforming into cold, a mixed mechanism of cold and heat may appear first, followed by complete transformation into cold, which is a gradual process. Refer to the section on "mixed cold and heat" disease mechanism for more details.
(IX) Dampness stagnation transforming into heat and dampness transforming into cold Whether external dampness invades the body or spleen deficiency generates internal dampness, if it lingers unresolved, it often leads to transformation into heat or cold depending on the predominance or decline of yin-yang qi. The mechanism of dampness stagnation transforming into heat usually involves internal retention of dampness with inherently vigorous yang, excessive use of warm and drying methods, or a diet favoring spicy, greasy, and sweet foods. Symptoms of dampness-induced illness appear first, followed by gradual signs of heat. If not fully transformed into heat, refer to the "mixed dampness-heat" disease mechanism; if fully transformed into heat, it resembles the "fire qi" disease mechanism. The mechanism of dampness transforming into cold often results from prolonged dampness with inherent yin exuberance, excessive use of cold and cooling agents, or a diet favoring raw and cold foods. Symptoms of dampness-induced illness appear first, gradually showing signs of mixed cold-dampness, rarely transforming into pure cold without dampness. For dampness transforming into cold, refer to the "mixed cold-dampness" disease mechanism.
(X) Dryness transforming into heat and dryness transforming into cold When dryness qi enters the body, depending on the abnormal exuberance of yin or yang in the constitution and the influence of seasonal climate, it can transform into heat or cold.
Dryness transforming into heat Yu Chang stated: "Fire seeks dryness," and considered dryness qi "akin to fire-heat" ("Shang Lun Hou Pian - Shang Lun Si Shi"). Wu Ju-tong also said: "Dryness qi... transforms into heat, damaging fluids." ( Wenbing Tiaobian , Shen Mu-nan's "Discussion on Dryness Disease"). This mainly refers to the pathological changes of fire-heat and yin damage during the course of dryness disease. Dryness qi transforming into heat often occurs in individuals with vigorous yang or inherent yin deficiency. Inherently vigorous yang qi makes the Six Climatic Factors prone to transforming into fire, so exposure to dryness qi often leads to heat transformation. Yin deficiency individuals, with often hyperactive yang, also frequently result in dryness qi transforming into heat. Additionally, whether dryness qi transforms into heat is closely related to the climate's warmth. As Fei Bo-xiong said: "Early autumn is still hot, so dryness is hot" ("Yi Chun Sheng Yi"). Yu Gen-chu also stated: "If there is prolonged drought without rain, and the autumn sun is scorching, those affected often suffer from warm dryness, which is dryness-heat" ( Tongsu Shanghan Lun ). This indicates that in early autumn, following the height of summer, the climate remains hot, and prolonged drought with intense autumn sun can be as scorching as midsummer. The dryness during this period often transforms into heat when affecting people. The pathological mechanism of dryness qi transforming into heat and generating fire can be referred to in the relevant section on "fire qi" disease mechanism.
Dryness transforming into cold Wu Ju-tong said: Dryness qi transforming into cold is the norm for dryness qi, indicating that dryness transforming into cold is not uncommon. The pathology of dryness transforming into cold is common in individuals with inherently deficient yang or exuberant yin. Those with yang deficiency or yin exuberance often have internal cold, so exposure to dryness qi also tends to transform into cold. Whether dryness qi transforms into cold is also related to the climate's temperature. For example, in late autumn, approaching early winter, as the cold season sets in and the climate cools, the dryness during this period easily transforms into cold, becoming cool dryness or even cold. Cold air can also cause fluids to congeal and not moisten, exacerbating dryness pathology. For dryness qi entering the interior and transforming into cold, refer to the relevant section on "cold qi" disease mechanism.
(11) Combined Pathogens of Internal and External Factors in the Mechanism of Disease Caused by the Six Climatic Factors. In the occurrence and evolution of diseases, there is often a combination of internal and external pathogens. For example, external wind and internal wind, external cold and internal cold, external dampness and internal dampness, external dryness and internal dryness, external heat (fire) and internal heat (fire). When combined pathogens are at play, they often present complex pathological changes of deficiency and excess, which are discussed below.
- External wind internal wind combined pathogens This mechanism of disease can generally be divided into two types: external wind triggering internal wind and internal wind being affected by external wind. External wind triggering internal wind can occur in internal damage Zabing and skin diseases. In internal damage Zabing, if the body's zang-fu organs are out of balance, yin-yang is biased, qi and blood flow counter, yang qi is excessive, and if care is not taken, wind pathogens can cause uncontrolled yang rising, internal stirring of liver wind, carrying phlegm and fire, driving blood upward, or obscuring the seven orifices, leading to apoplexy involving zang-organs and meridians. In some stubborn and itchy skin diseases, there is often a pathology of "blood deficiency producing wind," and when external wind is encountered again, it often leads to internal wind agitation, causing acute itching attacks. Internal wind being affected by external wind refers to those who already have internal stirring of liver wind being affected by external wind again, such as apoplexy with a new common cold, or "blood deficiency producing wind" diseases being affected by new pathogens. In summary, external wind triggering internal wind and internal wind being affected by external wind are mainly distinguished by different stages in the evolution of the disease mechanism, both belonging to external wind internal wind combined pathogens.
- External cold internal cold combined pathogens This mechanism of disease can be divided into external cold leading to internal cold and internal cold attracting external cold. When the body is not properly cared for, external cold invades and fails to be expelled, gradually entering the interior and lingering, as cold is a yin pathogen, it easily damages yang qi, and prolonged yang damage often leads to yin exuberance and internal cold, resulting in internal and external cold combined. There are also those with inherent internal cold, whose yang qi is deficient, and yang qi cannot spread, leading to the skin's striae and interstice losing warmth and the defensive qi being weak, often easily affected by cold pathogens, causing internal and external cold combined pathological changes. Refer to the "cold qi mechanism of disease" section.
- External dampness internal dampness combined pathogens The external and internal combined pathogens of dampness mechanism of disease also have external dampness leading to internal dampness and internal dampness attracting external dampness. External dampness mostly affects the muscles and meridians, but dampness is a yin pathogen, heavy and sticky, lingering and hard to resolve, and the spleen belongs to earth, dampness is earth qi, similar qi attracts, so prolonged dampness often leads to spleen yang being depressed or injured, causing failure in lifting and transporting, and water and grain essence cannot be spread, accumulating to produce internal dampness. At this time, the dampness in the muscles and meridians still exists, adding to the newly produced internal dampness, forming external and internal combined dampness pathology. External dampness invading the body is closely related to climate and living in damp places, especially those with inherent spleen dampness are prone to illness. The pathology is as You Zai dampness said: "Dampness stroke must first have internal dampness and then be affected by external dampness, so the person usually has deficient earth virtue and dampness moving internally, thus qi transformation is not uniform and dampness invades externally, external and internal combined pathogens" (Jingui Xindian·痙濕暍篇). The external and internal combined pathogens of dampness mechanism of disease can be referred to in the "dampness mechanism of disease" section.
- External dryness internal dryness combined pathogens The external and internal combined pathogens of dryness qi mechanism of disease also have external dryness leading to internal dryness and internal dryness being easily affected by external dryness. Dryness, like fire and heat, easily consumes yin fluids, domination of dryness causing dry symptoms, often leading to body fluids deficiency. External dryness attacking the surface, if gradually deepening, injures the lung and stomach, lung fluids are injured, causing lung qi to fail in dispersion and descending. If lung qi fails in dispersing body fluids, the limbs lose nourishment, becoming dry, thin, and atrophied; lung qi failing to descend causes qi counterflow and panting; and dryness-heat damaging the lung can cause loss of control in governance, body fluids failing to disperse, and water fluids directly descending, leading to frequent urination, thus body fluids are further consumed, and dryness increases. Upper dryness unresolved, gradually transmitting to the middle energizer, stomach fluid deficiency, becomes stomach dryness. Or stomach qi ascending counterflow causing vomiting and hiccup; or pathogenic heat killing grain causing rapid digestion and hunger, thirst for cold drinks, etc. Those with inherent yin deficiency or blood deficiency internal dryness are often easily affected by external dryness in autumn, forming internal and external combined pathogens. Shi Shou-tang discussed this mechanism of disease quite clearly, saying: "All these dryness diseases mostly occur in those with yin deficiency and hard-working people, in the hot summer, fluids consumed by sweat, water exhausted and metal dry, internal qi already dry, with dryness feeling dryness, similar qi attracts, most easily" (Yiyuan·dryness qi discussion). Dryness qi harming people, internal and external combined pathogens, its mechanism of disease can be referred to in the "dryness qi mechanism of disease" section.
- The combined pathogens of external heat (fire) and internal heat (fire) can be divided into two situations: external heat leading to internal heat (fire), and internal heat (fire) being further affected by external heat. The former is mainly seen in the development of external contraction warm febrile disease syndromes, such as when warm pathogens are contracted externally and fail to be dispersed with cooling methods, leading to pathogenic heat entering the interior and even transforming into fire, damaging yin and resulting in internal blazing of fire heat. The mechanism of disease is characterized by both the transformation of external heat into strong fire upon entering the interior, as well as factors such as kidney yin nearing exhaustion, yin failing to control yang, and deficiency fire flaming upward. This is the so-called pathology of external heat leading to internal heat, with combined internal and external pathogens. In cases where there is pre-existing internal heat (fire) and external heat is contracted, leading to combined internal and external heat, such as in external-contraction febrile diseases like spring warmth and latent summerheat, the pathogenic heat (or cold pathogens transforming into heat) is initially contracted but does not immediately cause illness, instead lying dormant within the body until spring or autumn, when new contraction of warm heat pathogens triggers the latent heat, resulting in the onset of the disease with dual exterior and interior heat pathology. In Zabing, conditions such as pre-existing liver fire exuberance or yin deficiency with internal heat are also prone to contracting warm heat pathogens. The latter, in particular, is more susceptible to damage from warm heat pathogens, leading to the pathology of combined internal and external heat. For the pathology of combined internal and external heat, refer to the "external fire and internal fire" mechanism of disease.