The Six Excesses (Liù Yín) are one of the causes of exogenous diseases. When there are abnormal changes in the climate of the natural world or when the body’s resistance to disease decreases, the Six Excesses—Wind (Fēng), Cold (Hán), Heat (Shǔ), Dampness (Shī), Dryness (Zào), and Fire (Huǒ)—become pathogenic factors that harm the body, leading to the occurrence of exogenous diseases.
■ Concept of the Six Excesses and Common Pathogenic Characteristics
1. Basic Concept of the Six Excesses
The Six Excesses refer to the six types of exogenous pathogenic factors: Wind (Fēng), Cold (Hán), Heat (Shǔ), Dampness (Shī), Dryness (Zào), and Fire (Huǒ). Under normal circumstances, these six are different climatic changes in nature, which are necessary conditions for the growth and survival of all living things, referred to as the “Six Qi”. Humans have adapted to the cyclical changes of these Six Qi over a long period, and generally, they do not cause disease. However, when the climate changes abnormally beyond the body’s adaptive capacity, or when the body’s righteous Qi (Zhèng Qì) is insufficient, leading to a decreased ability to resist disease, these Six Qi can become pathogenic factors. At this point, the harmful Six Qi are referred to as the “Six Excesses”. The term “Excess” implies an overabundance or immersion. Since the Six Excesses are pathogenic evil Qi, they are also called the “Six Evils”.
The pathogenicity of the Six Excesses is relative to the normality of climate changes in nature, mainly reflected in two aspects: first, the climate change is too intense or abrupt compared to the usual seasonal changes in that region, such as extreme cold or heat, or when there is an out-of-season occurrence of certain Qi, or when it is excessive or insufficient, such as warmth in winter when it should be cold; if the body cannot adapt, it can lead to disease, at which point the Six Qi are considered to be excessive and thus become the Six Excesses. Second, the pathogenic conditions of climate change are relative to the strength of the body’s righteous Qi and its adaptability. If the climate changes abnormally, individuals with strong righteous Qi can self-regulate and remain healthy, while those with weak righteous Qi may succumb to disease; or even if the climate changes normally, individuals with insufficient righteous Qi or weaker constitutions may still fall ill, thus the Six Qi become pathogenic factors for them, and the resulting diseases fall under the category of Six Excesses.
2. Common Characteristics of Diseases Caused by the Six Excesses
The diseases caused by the Six Excesses generally have the following common characteristics:
(1) Exogenous Nature
The Six Excesses typically invade the body through the skin or the mouth and nose, or both simultaneously. For example, Wind, Cold, and Dampness easily invade the skin, while Warmth and Dryness can enter through the mouth and nose. Since the Six Excesses are all external factors that invade the body, they are referred to as exogenous pathogenic factors, and the diseases they cause are termed “exogenous diseases”. Some exogenous diseases may present with fever symptoms in the early stages, hence they are also called “exogenous febrile diseases”.
(2) Seasonal Nature
The diseases caused by the Six Excesses often exhibit significant seasonal characteristics. For instance, Wind diseases are more common in spring, Heat diseases in summer, Damp diseases in late summer, Dryness diseases in autumn, and Cold diseases in winter. The diseases caused by the Six Excesses are closely related to seasonal climate changes, thus they are also referred to as “seasonal diseases” or “timely diseases”. Due to the peculiarities of abnormal climate changes, Cold diseases can also occur in summer, and Heat diseases can appear in winter.
(3) Regional Nature
The diseases caused by the Six Excesses are closely related to the environmental conditions of the living and working areas. For example, the northwest region is prone to Dryness diseases, the northeast to Cold diseases, the Jiangnan region to Damp-Heat diseases; those living in humid environments are more likely to suffer from Damp diseases; and those working in high-temperature environments may experience Dryness or Fire diseases.
(4) Coexisting Nature
The Six Excesses can cause disease either alone or in combination with two or more types simultaneously. For example, Wind-Heat colds, Damp-Heat colds, and Wind-Cold-Damp Bi syndrome. As stated in the “Su Wen: Bi Lun”, “When Wind, Cold, and Damp Qi mix together, they combine to form Bi syndrome. If Wind Qi is predominant, it is called ‘Xing Bi’; if Cold Qi is predominant, it is called ‘Tong Bi’; if Damp Qi is predominant, it is called ‘Zhang Bi’.”
The diseases caused by the Six Excesses also exhibit characteristics of transformation, such as Cold evil causing disease can transform from Cold syndrome to Heat syndrome if not treated properly.
In addition to climatic factors, the Six Excesses also include the effects of biological (bacteria, viruses, etc.), physical, and chemical pathogenic factors acting on the body.
■ Nature and Pathogenic Characteristics of the Six Excesses
The nature and pathogenic characteristics of Wind, Cold, Heat, Dampness, Dryness, and Fire are primarily derived from a comparative analysis of natural phenomena and the clinical manifestations of human diseases, validated through repeated clinical practice and continuous deduction, induction, and summarization.
1. Wind Evil
Any external evil that has characteristics of movement, non-stationarity, and lightness is called Wind evil.
When Wind Qi is excessive and harms the body, it is termed Wind evil. Wind evil is most commonly seen in spring, but it is present throughout the year and can occur in all seasons. Wind evil typically invades the body through the skin, leading to external Wind diseases. Wind is a very important pathogenic factor for exogenous diseases, hence it is referred to as “the leader of the Six Excesses”.
■ Nature and Pathogenic Characteristics of Wind Evil
(1) Wind is a Yang evil, light and dispersive, easily attacking Yang locations.
Wind evil has characteristics of lightness, dispersion, and upward movement, thus it is classified as a Yang evil. The dispersive nature of Wind means it can easily cause the pores to open, leading to sweating and aversion to wind. When Wind evil invades, it often affects the Yang areas of the body (head, face, throat, skin), as stated in the “Su Wen: Tai Yin Yang Ming Lun”, “Those harmed by Wind are first affected above.” Symptoms may include headaches, throat itching, coughing, and facial swelling.
(2) Wind is prone to movement and change.
“Prone to movement” means that Wind is characterized by its ability to move and change, thus its pathogenicity is marked by the shifting of the disease location and the lack of fixed points. For example, Bi syndrome caused by the combination of Wind, Cold, and Damp Qi may present with migratory joint pain, where the pain is not fixed, referred to as “Xing Bi” or “Feng Bi”. “Prone to change” indicates that Wind evil can cause sudden and unpredictable changes in the disease, such as urticaria (hives) caused by Wind, which may present as wheals on the skin that appear and disappear, with itching that comes and goes. Exogenous diseases led by Wind generally have an acute onset and can change rapidly. For instance, Wind affecting the head and face may suddenly cause facial paralysis; in children, Wind Water syndrome may initially present with superficial symptoms but can quickly lead to swelling of the face and body, reduced urination, etc. Thus, the “Su Wen: Feng Lun” states, “Wind is prone to movement and change.”
(3) Wind is active.
“Active” means that Wind evil has the characteristic of being unstable and unpredictable. For example, when external Wind affects the facial muscles, it may cause twitching or facial paralysis, indicating Wind invasion of the meridians; or after an injury from a sharp object, if Wind evil invades, it may lead to convulsions of the limbs and opisthotonos, indicating tetanus. Thus, the “Su Wen: Yin Yang Ying Xiang Da Lun” states, “When Wind prevails, it causes movement.”
(4) Wind is the leader of all diseases.
“Leader” means it is the beginning and the foremost. Wind is the leader of all diseases, which means that Wind evil often combines with other evils to harm the body, serving as the precursor to exogenous diseases. Since Wind evil is present throughout the year, its active nature means that Cold, Damp, Heat, Dryness, and Fire evils often attach themselves to Wind to invade the body, leading to various exogenous diseases such as Wind-Cold, Wind-Damp, Wind-Heat, and Wind-Dryness syndromes. As stated in the “Lin Zheng Zhi Nan Yi An: Volume Five”, “Among the Six Qi, only Wind can encompass all five Qi; if it combines with Cold, it is called Wind-Cold; if it combines with Heat, it is called Heat-Wind; if it combines with Damp, it is called Wind-Damp; if it combines with Dryness, it is called Wind-Dryness; if it combines with Fire, it is called Wind-Fire. This is because Wind can stir up these five Qi and harm the body, hence it is called the leader of all diseases… From this, it can be seen that many diseases arise from Wind.” Additionally, it indicates that Wind evil is the most frequent cause of disease. Wind evil is present throughout the year, thus the opportunities for disease to occur are numerous; Wind evil can harm both the exterior and interior of the body, leading to various disease presentations. Ancient texts even referred to Wind evil as a general term for exogenous pathogenic factors. For example, the “Su Wen: Gu Kong Lun” states, “Wind is the beginning of all diseases.” The “Su Wen: Feng Lun” states, “Wind is the leader of all diseases.”
2. Cold Evil
Any external evil that has characteristics of coldness, condensation, and contraction is called Cold evil.
Excessive coldness that harms the body is termed Cold evil. Cold evil is commonly seen in winter, particularly when water freezes and the ground cracks, leading to many cases of Cold diseases; however, Cold evil can also occur in other seasons, such as during sudden drops in temperature, excessive exposure to cold, sleeping in cold conditions, or consuming excessive cold foods, which are also significant causes of Cold evil.
The diseases caused by Cold evil are referred to as external Cold diseases. When Cold invades the skin, it obstructs the Yang Qi, leading to what is termed “Shang Han”; when Cold evil penetrates the interior and harms the Yang Qi of the organs, it is referred to as “Zhong Han”.
■ Nature and Pathogenic Characteristics of Cold Evil
(1) Cold is a Yin evil, easily harming Yang Qi.
Cold is a manifestation of excessive Yin, thus it is classified as a Yin evil. When Cold evil harms the body, the body’s Yang Qi rises to resist it. Yang Qi can normally control Yin and expel Cold, but if Cold evil is too strong, Yang Qi may not only be insufficient to expel it but may also be harmed by it, leading to the principle that “when Yin is excessive, Yang becomes ill”. Therefore, exposure to Cold evil is most likely to damage the body’s Yang Qi. For example, when external Cold invades the skin, the Yang Qi is obstructed, leading to symptoms such as aversion to cold, fever, no sweating, nasal congestion, and sneezing; if Cold evil penetrates the spleen and stomach, harming the Spleen Yang, symptoms may include cold pain in the abdomen, vomiting, and diarrhea; if Cold evil penetrates the Shao Yin, damaging the heart and kidney Yang Qi, symptoms may include aversion to cold, curled up posture, cold hands and feet, clear and profuse urination, mental fatigue, and a thin pulse.
(2) Cold has a nature of stagnation and causes pain.
Stagnation refers to blockage. The nature of Cold is to cause stagnation, meaning that Cold evil can easily cause Qi, blood, and body fluids to congeal and obstruct the meridians. The smooth flow of Qi, blood, and body fluids in the body relies on the warmth provided by Yang Qi. Once the Yin and Cold evil invades, Yang Qi is damaged, losing its warmth, which can lead to obstruction of the meridians and blood flow, resulting in pain. Therefore, pain is an important clinical manifestation of diseases caused by Cold evil. Pain caused by Cold has two characteristics: first, there is a clear cause of exposure to Cold; second, the pain is relieved by warmth and worsens with cold. Due to the different locations affected by Cold evil, various pain symptoms may arise. For example, if Cold invades the skin and meridians, leading to stagnation of Qi and blood, there may be pain in the head, body, and joints; if the main symptom is cold pain in the joints, it is termed “Han Bi” or “Tong Bi”; if Cold evil penetrates the stomach and intestines, it may cause severe abdominal pain; if Cold invades the liver meridian, cold pain may be felt in the lower abdomen or external genitalia. As stated in the “Su Wen: Bi Lun”, “Pain is often due to excessive Cold; pain occurs because of Cold.”
(3) Cold has a nature of contraction.
Contraction refers to the action of drawing in. The “Su Wen: Ju Tong Lun” states, “When it is cold, Qi contracts.” The nature of Cold is to cause contraction, meaning that when Cold evil invades the body, it can cause the Qi mechanism to contract, leading to the tightening of the pores, meridians, and tendons. For example, when Cold evil harms the skin, the Yang Qi is obstructed and cannot be released, leading to symptoms such as aversion to cold and no sweating; when Cold invades the blood vessels, Qi and blood become stagnant, leading to pain in the head and body, and a tight pulse; when Cold invades the meridians and joints, it can cause tightness and pain, making movement difficult, or lead to cold limbs and numbness. The “Su Wen: Ju Tong Lun” states, “When Cold Qi invades the pulse, the pulse becomes cold; when the pulse is cold, it contracts, and when it contracts, the pulse becomes tight, leading to sudden pain.” Contraction and tightness are manifestations of the damage caused by Cold evil, leading to the contraction of the meridians and blood vessels.
3. Heat Evil
Any external evil that has characteristics of heat, elevation, and dampness is called Heat evil, which occurs from the summer solstice to the beginning of autumn.
Heat is the main Qi of summer. When excessive heat harms the body, it is termed Heat evil. Heat evil has significant seasonal characteristics, primarily occurring from the summer solstice to the beginning of autumn. Thus, the “Su Wen: Re Lun” states, “Diseases occurring before the summer solstice are termed Warm diseases, while those occurring after are termed Heat diseases.”
■ Nature and Pathogenic Characteristics of Heat Evil
(1) Heat is a Yang evil, characterized by its heat.
Heat is the manifestation of the fire and heat of summer, thus Heat evil is classified as a Yang evil. Heat evil typically manifests with a series of Yang heat symptoms, such as high fever, irritability, flushed face, and a rapid pulse.
(2) Heat is upward-moving and can disturb the mind, harming fluids and consuming Qi.
“Upward-moving” means that Heat has a tendency to rise. Heat, being a Yang evil, tends to disturb the mind, or invade the head, leading to symptoms such as chest discomfort, dizziness, flushed face, etc. “Disturb” means that Heat evil can invade the body, causing the pores to open and leading to excessive sweating. The “Su Wen: Ju Tong Lun” states, “When it is hot, Qi leaks out.” Excessive sweating not only harms body fluids but also consumes Qi, thus in clinical practice, in addition to symptoms of thirst and a preference for drinking, there are often signs of shortness of breath, fatigue, and in severe cases, excessive consumption of Qi and fluids can lead to sudden fainting and loss of consciousness. Therefore, the “Su Wen: Ci Zhi Lun” states, “Qi deficiency and body heat can be caused by Heat evil.”
(3) Heat often accompanies Dampness.
The summer climate is hot and often rainy and humid, leading to the combination of Heat and Dampness, thus Heat evil often presents with Dampness-related symptoms. In addition to fever and thirst, common symptoms include a feeling of heaviness, difficulty sweating, fatigue, chest tightness, nausea, and loose stools.
4. Damp Evil
Any external evil that has characteristics of heaviness, stickiness, and downward movement is called Damp evil.
When Dampness is excessive and harms the body, it is termed Damp evil. Damp evil is most commonly seen in the long summer, but it can occur in all seasons. The long summer, also known as “late summer”, occurs during the transition from summer to autumn, when Yang heat is still strong, and there is much rain, leading to the highest levels of humidity throughout the year. The diseases caused by Damp evil are referred to as external Damp diseases. External Damp diseases are often caused by humid climates, exposure to rain, living in damp environments, or working in water.
■ Nature and Pathogenic Characteristics of Damp Evil
Damp evil is characterized by heaviness and stickiness, belonging to Yin, and its nature is sticky, stagnant, and pervasive, leading to various pathological changes.
(1) Damp is a Yin evil, easily harming Yang Qi and obstructing Qi mechanisms.
Dampness is similar to water, thus it is classified as a Yin evil. When Yin evil invades, the body’s Yang Qi struggles against it, making it easy for Damp evil to harm Yang Qi. As stated in the Qing dynasty text by Ye Gui, “When Dampness prevails, Yang is weak.” The Spleen governs the transformation and transportation of fluids, preferring dryness and disliking Dampness; thus, when Damp evil invades, it can easily obstruct the Spleen, leading to Spleen Yang deficiency, resulting in internal accumulation of fluids, causing diarrhea, edema, and phlegm. As stated in the “Su Wen: Liu Yuan Zheng Ji Da Lun”, “When Dampness prevails, it leads to leakage; in severe cases, it can cause water retention and abdominal swelling.”
Damp evil often lingers in the organs and meridians, obstructing the Qi mechanisms, leading to abnormal ascension and descent of Qi in the organs, and causing stagnation in the meridians. For example, if Dampness obstructs the chest, it can lead to fullness and discomfort; if Dampness obstructs the middle burner, it can lead to abdominal distension and loss of appetite; if Dampness obstructs the lower burner, it can lead to fullness in the lower abdomen and difficulty urinating.
(2) Damp is heavy and turbid.
“Heavy” refers to the sensation of heaviness and difficulty in movement. When Damp evil invades, it often presents with a feeling of heaviness and difficulty in movement, such as heaviness in the head and body, and heaviness in the limbs. When Damp evil invades the skin, it can obstruct the Yang Qi, leading to symptoms such as a heavy head, as stated in the “Su Wen: Sheng Qi Tong Tian Lun”, “Due to Dampness, the head feels heavy.” Damp evil can also obstruct the meridians and joints, preventing the Yang Qi from circulating, leading to numbness of the skin and heavy joint pain, or difficulty in movement, often referred to as “Damp Bi” or “Turbid Bi”. “Turbid” refers to the presence of foul and unclear secretions and excretions. When Damp evil is present, it can lead to symptoms such as facial blemishes, excessive phlegm, or turbid urine, and in women, excessive vaginal discharge; if Dampness accumulates in the intestines, it can lead to diarrhea, dysentery, or blood in the stool; if Damp evil invades the skin, it can lead to eczema or weeping dermatitis.
(3) Damp is sticky and stagnant.
“Sticky” refers to the sensation of stickiness and discomfort; “stagnant” refers to blockage. When Damp evil causes disease, its sticky and stagnant nature is mainly reflected in two aspects: first, the symptoms are sticky. When Damp evil is present, it often presents with symptoms of sticky secretions and excretions, such as unsatisfactory bowel movements in Damp-Heat dysentery, difficulty urinating in Damp-Heat syndrome, and sticky sweat, as well as a thick and greasy tongue coating. Second, the course of the disease is prolonged. Due to the sticky nature of Dampness, it can obstruct the Qi mechanisms, leading to prolonged illness, recurrent episodes, or chronic conditions such as Damp-Heat, eczema, and Damp Bi (Turbid Bi), which are difficult to resolve quickly. Wu Tang’s “Wen Bing Tiao Bian: Upper Jiao” states, “Its nature is sticky and turbid, unlike Cold evil, which can be resolved with one sweat, or Warm evil, which can be resolved with one cooling treatment, thus it is difficult to resolve quickly.”
(4) Damp tends to move downward, easily affecting the lower body.
Dampness, being similar to water and belonging to Yin, has a downward tendency, thus Damp evil often affects the lower parts of the body. For example, conditions such as edema, eczema, and athlete’s foot are more common in the lower limbs. The “Su Wen: Tai Yin Yang Ming Lun” states, “Those harmed by Dampness are first affected below.” Symptoms such as turbid urine, diarrhea, dysentery, and excessive vaginal discharge in women are often caused by Damp evil affecting the lower body.
5. Dry Evil
Any external evil that has characteristics of dryness and contraction is called Dry evil.
Dryness is the main Qi of autumn. In autumn, the weather becomes more reclusive, the air becomes clear and crisp, and the climate becomes dry, lacking moisture. When Dryness is excessive, it harms the body, leading to Dry evil. Dry evil typically invades the body through the mouth and nose, primarily affecting the lungs, leading to what is termed external Dry diseases.
External Dryness can be classified into Warm Dryness and Cool Dryness: in early autumn, there may still be residual heat from late summer, with prolonged sunny days and no rain, leading to Warm Dryness; in late autumn, the cold air combines with Dryness, leading to Cool Dryness.
■ Nature and Pathogenic Characteristics of Dry Evil
(1) Dryness is characterized by its aridity, easily harming body fluids.
Dry evil is a dry and astringent pathogenic factor that invades the body, easily damaging body fluids and leading to various dry and astringent symptoms, such as dryness of the mouth and nose, thirst, dry skin, and in severe cases, cracking, lackluster hair, reduced urination, and constipation. Thus, the “Su Wen: Yin Yang Ying Xiang Da Lun” states, “When Dryness prevails, it causes dryness.”
(2) Dryness easily harms the lungs.
The lungs are delicate organs that prefer moisture and dislike dryness. The lungs govern Qi and respiration, directly connecting with the external atmosphere, and they also open to the skin and nose. Dry evil often enters through the mouth and nose, thus it is most likely to damage lung fluids, affecting the lung’s ability to disperse and descend Qi, and may even dry out the lung meridians, leading to symptoms such as dry cough with little phlegm, or phlegm that is difficult to expectorate, or even blood-streaked phlegm, and in severe cases, wheezing and chest pain. Since the lungs and large intestine are interrelated, when lung fluids are depleted, the large intestine may also lose moisture, leading to constipation.
6. Fire (Heat) Evil
Any external evil that has characteristics of heat and elevation is called Fire evil.
Fire is most prevalent in summer, but unlike Heat, it does not have significant seasonal characteristics and is not limited by seasonal climate. Therefore, when Fire is excessive, it harms the body and can occur throughout the year.
Fire and Heat are different names for the same category, both representing excessive Yang, and the pathogenic effects are fundamentally similar. The main difference between Fire evil and Heat evil is that Heat evil typically presents with systemic febrile symptoms, while Fire evil often presents with localized symptoms, such as localized redness, swelling, heat, and pain, or sores in the mouth and tongue, or red and swollen eyes. Additionally, there is also Warm evil, which is a pathogenic factor leading to Warm diseases, generally used in the context of Warm diseases.
■ Nature and Pathogenic Characteristics of Fire Evil
(1) Fire is a Yang evil, characterized by its upward movement.
The nature of Fire is to burn and rise, thus it is classified as a Yang evil. Yang evils harm the body, leading to an excess of Yang Qi, resulting in symptoms of excess heat, such as high fever, aversion to heat, thirst, sweating, and a rapid pulse. Fire tends to invade the upper parts of the body, thus Fire diseases often occur in the upper body, especially the head and face. Symptoms may include red and swollen eyes, sore throat, mouth ulcers, bitter taste, dry throat, swollen gums, headaches, dizziness, and ear swelling or pus discharge.
(2) Fire easily disturbs the mind.
Fire is associated with the heart, thus Fire evil entering the Ying and blood easily affects the mind, leading to symptoms such as restlessness, insomnia, or severe cases of confusion and delirium. Therefore, the “Su Wen: Zhi Zhen Yao Da Lun” states, “All heat-related confusion belongs to Fire” and “All manic episodes belong to Fire.”
(3) Fire easily harms fluids and consumes Qi.
Fire evil harms the body, leading to internal heat, which can cause fluids to leak out, resulting in Qi loss; on the other hand, it can directly scorch and consume body fluids, depleting Yin Qi. Therefore, diseases caused by Fire evil often present with significant heat symptoms, along with signs of thirst and a preference for cold drinks, dry throat, dark and scanty urine, and constipation. When Yang heat is excessive, it can lead to fatigue, shortness of breath, and in severe cases, a collapse due to the loss of fluids and Qi.
(4) Fire easily generates Wind and stirs blood.
“Generates Wind” means that Fire evil invading the body can scorch fluids, harming the liver Yin, leading to a lack of nourishment and moisture in the tendons and meridians, which can easily cause “Wind generated by extreme heat”. Clinical manifestations may include high fever, confusion, convulsions, and upward eye movement. “Stirring blood” means that Fire evil entering the blood vessels can easily cause blood to flow erratically. When Fire evil invades the blood vessels, it can accelerate blood flow, leading to a rapid pulse, and in severe cases, it can scorch the blood vessels, causing various bleeding disorders such as hemoptysis, epistaxis, hematochezia, hematuria, skin purpura, excessive menstruation, and uterine bleeding.
(5) Fire evil easily causes sores and abscesses.
When Fire evil enters the blood level, it can accumulate locally, eroding flesh and leading to sores and abscesses. The “Ling Shu: Yong Ju” states, “When excessive heat persists, it leads to flesh rotting, and when flesh rots, it becomes pus, hence it is called an abscess.” The clinical manifestations of abscesses caused by Fire toxicity are characterized by localized redness, swelling, and pain.
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