Cold and heat are the fundamental principles for differentiating the nature of diseases. The nature of a disease is not simply classified as cold or heat. As stated in the “Jing Yue Quan Shu – Chuan Zhong Lu”: “Cold and heat are transformations of yin and yang.” The “Lei Jing – Disease Classification” also states: “When water and fire lose their harmony, it results in cold and heat.” Since cold and heat prominently reflect the relative excess and deficiency of yin and yang in the body during illness, and the basic nature of pathogenic factors belongs to either yin or yang, it is said that cold and heat are the guiding principles for differentiating the nature of diseases.
Pathogenic factors can be divided into yang and yin pathogens, while the righteous qi can be divided into yang qi and yin fluids. Yang pathogens can cause disease by leading to an excess of yang qi and injuring yin fluids, or by depleting yin fluids and causing an excess of yang qi, both of which can manifest as heat syndromes. Yin pathogens can lead to an excess of yin qi and damage yang qi, or cause yang qi to be deficient and yin cold to prevail, both of which can manifest as cold syndromes. The saying “Excess of yang leads to heat, excess of yin leads to cold” and “Deficiency of yang leads to cold, deficiency of yin leads to heat” reflects this principle. This indicates that the understanding of cold and heat syndromes, based on the analysis of the yin or yang nature of pathogenic factors and the analysis of the excess and deficiency of the body’s yin and yang, is fundamentally consistent. The symptoms of aversion to cold (and fear of cold), fever, and the differentiation of cold and heat syndromes in the Eight Principles are related yet distinct; they should not be confused. Aversion to cold and fever are merely phenomena of the disease, while the cold and heat syndromes represent a judgment of the essence of the disease. The differentiation of cold and heat syndromes serves as a guide to determine whether the nature of the disease is cold or heat, providing a basis for treatment to dispel cold or clear heat.
1. Differentiation of Cold Syndromes
Cold syndromes refer to symptoms resulting from the invasion of cold pathogens or the manifestation of excess yin and deficiency of yang in the body. They are often caused by external cold pathogens, prolonged internal injury, depletion of yang qi, or excessive consumption of cold and raw foods, leading to an internal excess of cold.
[Clinical Manifestations] The clinical manifestations of various cold syndromes are not entirely consistent, but common symptoms include: aversion to cold with a preference for warmth, pale complexion, cold limbs curled up, lack of thirst with a pale tongue, clear and thin phlegm, clear and long urine, loose stools, a white and moist tongue coating, and a slow or tight pulse.
[Mechanism Analysis] Cold pathogens inhibit yang qi, or when yang is deficient and yin cold prevails, the body loses warmth, resulting in symptoms such as aversion to cold, fear of cold, cold limbs, cold pain, preference for warmth, and curling up. Cold does not consume fluids, and since the fluids are not damaged, the patient does not feel thirsty, and secretions such as phlegm, saliva, and urine are clear and cold, with a white and moist tongue coating.
[Key Points for Differentiation] The clinical differentiation of this syndrome should focus on the following two points:
1. The main pathogenesis of this syndrome is the internal excess of yin cold or insufficient yang qi.
2. Symptoms such as aversion to cold with a preference for warmth, cold limbs curled up, pale complexion, clear and thin secretions and excretions, and a white and slippery tongue coating serve as the basis for differentiation.
Cold syndromes can be classified into two major categories: excess cold syndromes and deficient cold syndromes, based on the patient’s constitution and the nature of the cold invasion. External cold invasion typically presents as exterior cold syndromes, while internal cold due to yang deficiency presents as interior cold syndromes. Common cold syndromes include both excess cold and deficient cold syndromes, which can further be divided into exterior cold and interior cold based on their location.
2. Differentiation of Heat Syndromes
Heat syndromes refer to symptoms resulting from the invasion of heat pathogens or the manifestation of yin deficiency and yang excess in the body. They are often caused by external heat pathogens, internal transformation of cold pathogens into heat, excessive emotional stress leading to heat, dietary irregularities leading to heat accumulation, or sexual activity depleting yin essence, resulting in internal heat.
[Clinical Manifestations] The clinical manifestations of various heat syndromes are not entirely consistent, but common symptoms include: aversion to heat with a preference for coolness, thirst with a preference for cold drinks, red face and eyes, restlessness, yellow and thick phlegm and nasal discharge, hemoptysis, epistaxis, dry stools, scanty yellow urine, red tongue with a yellow and dry coating, and a rapid pulse.
[Mechanism Analysis] The invasion of heat pathogens leads to an excess of yang, resulting in excessive heat production, which manifests as fever, aversion to heat, red face and eyes, red tongue with a yellow coating, and thick yellow nasal discharge, along with a rapid pulse. Excess heat damages fluids, leading to thirst with a preference for cold drinks, dry stools, and scanty yellow urine. Heat pathogens can also cause blood to move recklessly, resulting in symptoms such as hemoptysis and epistaxis.
[Key Points for Differentiation] When differentiating this syndrome, the following points should be noted:
1. The main pathogenesis of this syndrome is the excess of yang heat or internal heat due to yin deficiency.
2. Symptoms such as fever, aversion to heat with a preference for coolness, red face, red tongue with a yellow coating, and a rapid pulse serve as the basis for differentiation.
3. Heat damages fluids, hence symptoms such as thirst with a preference for cold drinks, dry stools, scanty yellow urine, and a dry tongue can also be used as reference for differentiation.
4. Heat damages blood vessels, leading to symptoms such as epistaxis and hemoptysis.
5. Differentiating between cold and heat syndromes: It is important to observe the overall presentation of the disease rather than relying on a single symptom for judgment. If a patient exhibits aversion to cold with a preference for warmth, lack of thirst, pale complexion, cold limbs, loose stools, clear and long urine, a pale tongue with a white coating, and a slow or tight pulse, it indicates a cold syndrome. Conversely, if a patient exhibits aversion to heat with a preference for coolness, thirst with a preference for cold drinks, red complexion, hot limbs, dry stools, scanty yellow urine, a red tongue with a yellow coating, and a rapid pulse, it indicates a heat syndrome. Heat syndromes can further be classified into excess heat, deficient heat, exterior heat, and interior heat, with each organ having its own specific manifestations of excess and deficient heat, which should be distinguished during clinical practice.
3. Differentiation of the Relationship Between Cold and Heat Syndromes
Although cold and heat syndromes are fundamentally different, they are interconnected and can appear simultaneously in the same patient, manifesting as mixed cold and heat symptoms. Under certain conditions, they can also transform into one another; during the progression of a disease, especially in critical stages, false cold or false heat phenomena may also occur.
(1) Differentiating the Mixed Cold and Heat Relationship
In the same patient, both cold and heat syndromes can appear simultaneously, referred to as mixed cold and heat. Common presentations include upper heat with lower cold, upper cold with lower heat, exterior cold with interior heat, and exterior heat with interior cold.
1. Differentiating Upper Heat and Lower Cold Syndromes refers to a condition where the upper body exhibits heat while the lower body exhibits cold. For example, a patient may present with symptoms of chest heat, bad breath, and swollen gums (upper heat) while simultaneously experiencing abdominal pain with a preference for warmth and loose stools (lower cold). This indicates upper heat in the upper jiao and lower cold in the middle jiao.
2. Differentiating Upper Cold and Lower Heat Syndromes refers to a condition where the upper body exhibits cold while the lower body exhibits heat. For example, a patient may present with cold pain in the stomach and vomiting of clear saliva (upper cold) while simultaneously experiencing scanty yellow urine and painful urination (lower heat). This indicates cold in the stomach and heat in the bladder.
3. Differentiating Exterior Cold and Interior Heat Syndromes refers to a condition where cold is present on the exterior while heat is present internally. This is often seen in patients with pre-existing internal heat who also contract wind-cold, or when external cold transforms into internal heat while the exterior cold has not yet resolved. Due to the varying locations of internal heat, the clinical manifestations of exterior cold and interior heat can differ, but common symptoms include: aversion to cold with fever, body aches, no sweating, restlessness, thirst, yellow urine, and a floating tight pulse.
4. Differentiating Exterior Heat and Interior Cold Syndromes refers to a condition where heat is present on the exterior while cold is present internally. This is often seen in patients with pre-existing internal cold who also contract wind-heat, or when exterior heat is mistakenly treated with purgatives, leading to damage of the spleen yang. Clinically, symptoms of fever, aversion to cold, headache, cough, and sore throat (exterior heat) may appear alongside loose stools, cold limbs, and clear and long urine (interior cold).
In the above mixed cold and heat syndromes, it is essential to distinguish between exterior and interior, upper and lower, meridians, and organs, as well as the relative predominance of cold and heat.
(2) Differentiating the Transformation Relationship Between Cold and Heat
1. Differentiating Cold Syndromes Transforming into Heat Syndromes refers to a process where a cold syndrome initially presents, followed by the emergence of heat symptoms, with the characteristics of the cold syndrome disappearing. This transformation often occurs due to an excess of yang qi in the body, causing cold pathogens to transform into heat; it can also result from improper treatment or excessive use of warming and drying herbs.
For example, an external cold invasion may initially present as an exterior cold syndrome with symptoms of aversion to cold, fever, body aches, no sweating, thin white tongue coating, and a floating tight pulse. As the condition progresses, the cold pathogen may transform into heat, leading to the disappearance of cold symptoms and the emergence of high fever, thirst, irritability, red tongue with yellow coating, and a large pulse, indicating a transformation from exterior cold syndrome to interior heat syndrome.
2. Differentiating Heat Syndromes Transforming into Cold Syndromes refers to a process where a heat syndrome initially presents, followed by the emergence of cold symptoms, with the characteristics of the heat syndrome disappearing. This transformation often occurs due to an excess of pathogenic factors and deficiency of righteous qi, leading to functional decline; it can also result from mismanagement or improper treatment that damages yang qi. This transformation can occur gradually or suddenly, such as in cases of prolonged heat dysentery leading to deficiency cold dysentery, which is a gradual transformation. Conversely, in cases of high fever with excessive sweating, or excessive vomiting or purging, leading to a sudden drop in body temperature, pale complexion, cold limbs, and a weak pulse, this indicates a rapid transformation into a cold syndrome (loss of yang).
The mutual transformation of cold and heat syndromes indicates a change in the essence of the disease. It reflects the relative strength of pathogenic factors and righteous qi; the transformation from cold to heat indicates that the righteous qi is still strong, and the cold pathogen is transforming into heat; the transformation from heat to cold indicates that the pathogenic factors are strong while the righteous qi is deficient.
4. Differentiating the True and False Relationship Between Cold and Heat
When cold or heat syndromes develop to an extreme, false phenomena may appear that are contrary to the essence of the disease, known as “true cold resembling heat” or “true heat resembling cold.” These false phenomena are often seen in critical stages of illness. If not carefully examined, they can lead to misdiagnosis and endanger life.
1. Differentiating True Cold and False Heat Syndromes (True Cold Resembling Heat) refers to a condition where true cold is present internally while false heat is manifested externally. The clinical presentation includes symptoms such as fever, thirst, red face, and a large pulse, resembling a heat syndrome. However, upon closer examination, the patient may feel hot but prefers to be covered, may be thirsty but only desires small amounts of warm drinks, and may have a red face that is pale and fluctuating. The pulse may be large but weak upon palpation, and there may also be cold limbs, clear and long urine, loose stools, and a pale tongue with a white coating, indicating an internal excess of yin cold, counteracting the external yang, also known as “excess yin counteracting yang.”
True cold and false heat syndromes should be distinguished from the “excess yang syndrome,” which refers to a critical condition where internal yin cold is excessive, and yang qi is repelled externally, leading to true cold internally and false heat externally. The clinical presentation includes symptoms such as floating heat, pale red cheeks, fluctuating color, or epistaxis, or dry mouth with floating teeth, thirst but desiring small amounts of warm drinks, restlessness, cold limbs, and a weak pulse. The key points for differentiation are: the patient feels hot but prefers to be covered, is thirsty but drinks little and prefers warm drinks, or rinses with water but does not want to drink, and exhibits restlessness but is clear-headed, with a large pulse that is weak upon palpation.
2. Differentiating True Heat and False Cold Syndromes (True Heat Resembling Cold) refers to a condition where true heat is present internally while false cold is manifested externally. The clinical presentation includes symptoms such as cold limbs, a deep pulse, resembling a cold syndrome. However, the hands and feet may be cold while the body is hot, with no aversion to heat but rather aversion to cold; the pulse may be deep but rapid and strong; and symptoms such as thirst with a preference for cold drinks, restlessness, dry stools, scanty yellow urine, and a red tongue with a yellow coating indicate a heat syndrome. The cold limbs and deep pulse are false cold symptoms caused by excessive internal heat, where yang qi is blocked and cannot express itself externally. The true essence of the disease is internal heat, indicating that yang is excessive internally while yin is counteracting externally, also known as “excess yang counteracting yin,” “yang counteracting,” or “heat counteracting.” The more severe the internal heat, the more severe the cold limbs, known as “the deeper the heat, the deeper the cold.”
In summary, the differentiation between true and false cold and heat requires understanding the entire process of the disease. The false phenomena often manifest in the limbs, skin, and complexion, while the internal manifestations of the organs, qi, blood, yin, and yang accurately reflect the essence of the disease. Therefore, during differentiation, internal signs such as tongue appearance, pulse quality, and urination should be used as diagnostic criteria. For example, a pale white tongue versus a red tongue, moist versus dry, thirsty versus not thirsty, strong versus weak pulse, clear and long urine versus scanty yellow urine. Additionally, false phenomena and true phenomena differ in facial redness and limb cold. For instance, false heat may present as a pale red color on the cheeks, while true heat presents as a fully flushed face. Similarly, false cold limbs may not desire warmth, while true cold limbs may curl up and desire warmth.
In conclusion, false phenomena are surface manifestations of the disease, while true phenomena reflect the essence of the disease. During differentiation, one should look beyond the surface to understand the essence and not be misled by false phenomena.
5. Differentiating the Relationship Between Cold and Heat Syndromes and Exterior and Interior Syndromes
The relationship between cold and heat syndromes includes various presentations such as exterior cold syndromes, exterior heat syndromes, interior cold syndromes, and interior heat syndromes.
(1) Differentiating Exterior Cold Syndromes refers to symptoms resulting from the invasion of cold pathogens on the exterior.
[Clinical Manifestations] Symptoms include significant aversion to cold, mild fever, body aches, no sweating, pale tongue with a thin white and moist coating, and a floating tight pulse.
[Mechanism Analysis] Cold is a yin pathogen that easily injures yang qi, causing contraction and stagnation. When cold pathogens invade the skin and muscles, the qi mechanism contracts, and the sweat pores close, leading to a loss of warmth on the body surface, resulting in significant aversion to cold, mild fever, and no sweating. The meridians and muscles are obstructed by cold, leading to body aches. A pale tongue with a thin white coating and a floating tight pulse are typical symptoms of exterior cold syndromes.
[Key Points for Differentiation] When analyzing this syndrome, the following points should be noted:
1. The main pathogenesis of this syndrome is the invasion of cold pathogens, leading to stagnation of the defensive qi and closure of the pores.
2. Symptoms such as significant aversion to cold, mild fever, no sweating, and a floating tight pulse serve as the basis for differentiation.
(2) Differentiating Exterior Heat Syndromes refers to symptoms resulting from the invasion of wind-heat pathogens on the exterior. This is often seen in spring and summer.
[Clinical Manifestations] Symptoms include fever, mild aversion to wind and cold, headache, possible sweating, dry mouth with mild thirst, red tongue edges, and a floating rapid pulse.
[Mechanism Analysis] Heat is a yang pathogen that has the properties of dispersing and ascending, leading to symptoms such as fever with mild aversion to wind and cold, and possible sweating. A red tongue with red edges and a floating rapid pulse are characteristic symptoms of exterior heat syndromes.
[Key Points for Differentiation] When identifying this syndrome, the following points should be noted:
1. The main pathogenesis of this syndrome is the invasion of wind-heat pathogens, leading to the loss of the lung’s ability to disperse.
2. Symptoms such as significant fever, mild aversion to cold, possible sweating, red tongue edges, and a floating rapid pulse serve as the basis for differentiation.
In summary, the differentiation of cold and heat syndromes is a method for identifying whether the nature of a disease is cold or heat. The occurrence of diseases is fundamentally related to the imbalance of yin and yang in the body, and cold and heat syndromes reflect the essence of the relative excess and deficiency of yin and yang. As stated in the “Suwen – Discussion on Yin and Yang Correspondences”: “Excess of yang leads to heat, excess of yin leads to cold.” The “Suwen – Discussion on Regulation of Menstruation” also states: “Deficiency of yang leads to external cold, deficiency of yin leads to internal heat.” The manifestations of excess yin or deficiency of yang correspond to cold syndromes, while excess yang or deficiency of yin correspond to heat syndromes. The key points for differentiation are that cold syndromes represent a group of symptoms and signs associated with cold, while heat syndromes represent a group of symptoms and signs associated with heat. The distinctions between cold and heat syndromes primarily manifest in the preferences for cold or heat, thirst or lack of thirst, complexion (pale or red), temperature of the limbs, quality of stools and urine, and changes in tongue and pulse. Generally, they can be classified into exterior cold syndromes, interior cold syndromes, exterior heat syndromes, and interior heat syndromes. Although cold and heat syndromes have fundamentally different manifestations of yin and yang, they can appear mixed during the disease process, such as upper heat with lower cold, upper cold with lower heat, exterior cold with interior heat, and exterior heat with interior cold. They can also transform into one another, such as cold syndromes transforming into heat syndromes and vice versa, as well as the appearance of true and false cold and heat phenomena, such as true cold resembling heat and true heat resembling cold, which should be carefully differentiated.
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