Introduction: This article is a compilation of the WeChat lecture notes from Teacher Zhou Shuijin’s “Learn TCM Easily” course. “Liu Yin” refers to external pathogenic factors in TCM etiology. Let’s explore how they harm our bodies and what symptoms arise when we are affected by them.
Teacher Zhou discusses the foundational theories of TCM
Lecture 18, 19 – External Pathogenic Factors of Liu Yin
Lecturer: Zhou Shuijin
Audio Compilation: Liu Qiong
Text Proofreading: Liu Qiong, Li Shihong
Text Organization: Nie Jing, Pan Liqin, Qi Hanchun、Feng Jianning, Quan Haiyan, Li Zhenbin
Dear students:
Good evening, everyone. Today we begin our study of Lecture 18 of “Foundational Theories of TCM,” which covers Chapter 6 of the textbook: Etiology. TCM etiology explores the various causes that can lead to the onset of diseases. This includes what constitutes a pathogenic factor, the concept of pathogenic factors, how they are formed, their properties, the characteristics of diseases they cause, and the distinctive symptoms these pathogenic factors exhibit in clinical practice. These are all very important components of the “Foundational Theories of TCM.”
First, let’s look at what pathogenic factors are. In TCM, pathogenic factors refer to causes that can disrupt the relative balance of Yin and Yang in our bodies, leading to disease. This includes Liu Yin, pestilential qi, emotional disturbances, overexertion, dietary irregularities, external injuries, phlegm, and blood stasis, collectively referred to as pathogenic factors, which were generally termed disease sources in ancient times. In the book “Medical Source Theory,” it is stated: “All suffering experienced by humans is called disease, and the factors causing this disease are termed causes.” In simpler terms, any factor that can induce disease effects under certain conditions is referred to as a pathogenic factor. The main objective of studying etiology is to investigate the nature of pathogenic factors and their characteristics in causing diseases. Our goal is to clarify the nature of these pathogenic factors and the characteristics they exhibit after causing diseases, which is essential for our learning and mastery. Only by understanding these can we deduce the pathogenic factors responsible when diseases occur, allowing us to address the root causes and effectively manage the diseases.
In clinical practice, TCM employs several methods to investigate pathogenic factors: First, the inquiry method, which involves discovering and identifying causes through detailed questioning of the patient’s illness history and related circumstances to infer the pathogenic factor; second, the dialectical inquiry method, which analyzes the clinical manifestations of symptoms to deduce the pathogenic factor. The dialectical inquiry method is the primary approach in TCM for investigating pathogenic factors. What is the difference between these two methods? For example, if a patient comes to you with a cold, you ask how they caught the cold and the course of their illness. They might tell you that during a hot summer day, they sweated profusely and then entered an air-conditioned room, resulting in a cold. You would deduce that this was caused by exposure to cold air, which is the inquiry method. The dialectical inquiry method, on the other hand, involves analyzing the symptoms and signs presented by the patient, using TCM diagnostic methods such as observation, listening, inquiry, and pulse-taking to gather all relevant information and determine the patient’s syndrome. For instance, if the patient presents with symptoms of an exterior wind-cold syndrome, we would know that the pathogenic factor is wind-cold. Why is the dialectical inquiry method the primary approach in TCM? Although the initial pathogenic factor may be clear, such as in the case of the cold caused by exposure to cold air, by the time the patient seeks treatment, several days may have passed. During this time, the patient may have attempted other treatments or neglected their diet, leading to changes in their condition. The cold syndrome may have transformed into a heat syndrome. Therefore, when we see the patient, the symptoms may no longer indicate a wind-cold cold but rather a wind-heat or food accumulation syndrome. In this case, we must investigate the current pathogenic factor, which may be wind-heat or food accumulation, rather than the initial cause of exposure to cold. Thus, the dialectical inquiry method is more suitable in clinical practice, as it allows us to understand the current symptoms and the underlying causes of the disease, enabling us to accurately address the pathogenic factor and effectively treat the disease. The dialectical inquiry method involves obtaining patient information through observation, listening, inquiry, and pulse-taking to determine the syndrome type, which facilitates better management of the condition. Of course, the inquiry method is also important, as the original cause of most diseases is often related to the current symptoms. Even if the pathogenic factors change over time, understanding the sequence of events helps us better comprehend the patient’s condition and aids in treatment.
I recall a patient from Gongqingcheng when I worked at the First People’s Hospital of Jiujiang. This patient primarily exhibited a fear of cold. They had been working in Guangzhou and were extremely sensitive to cold, having sought treatment for seven years across various locations, consulting both TCM and Western medicine, and even visiting a psychiatric hospital. Others believed they were mentally unstable, as Western medical examinations revealed no significant issues, yet their symptoms were severe. To what extent? They wore a cotton coat even in the summer and did not sweat. If we analyze this condition solely based on the symptom of fear of cold, we will later learn in “Diagnosis” that most TCM practitioners might consider this a Yang deficiency. I reviewed the prescriptions from many doctors, which primarily consisted of warming Yang, tonifying Yang, and dispelling cold herbs, but the patient’s symptoms did not improve significantly and worsened over the years. At this point, I employed the inquiry method, asking about the patient’s illness history. I learned that they initially worked in Guangzhou making tofu, where the weather was hot, and they sweated a lot. After stopping, they would easily catch a cold from the wind. This indicated that the initial cause was a wind-cold cold. After experiencing a fever from the wind-cold cold, they received an injection, which resolved the fever, but the fear of cold persisted and worsened over the years. When I inquired further and combined this with the four diagnostic methods, I found that although the patient had been ill for a long time, their condition was still due to wind-cold on the surface. At this point, we could not rely on conventional wisdom to judge that a long-term patient with a fear of cold must be a Yang deficiency case. Instead, we used a very simple treatment for colds to dispel wind and cold, recalling that we used a modified Gui Zhi Tang prescription, and the patient recovered quickly. With acupuncture treatment, they were completely well in just over ten days. This patient was even featured in a television report due to the complexity of their case, which had a significant impact. This case teaches us that in clinical practice, we must thoroughly inquire about the patient’s illness history. When investigating the cause of a patient’s illness, the first step is to ask detailed questions about the entire course of their illness and understand their treatment history. Then, based on the information gathered through observation, listening, inquiry, and pulse-taking, we can gain a comprehensive understanding of the patient’s condition, which is more conducive to effective treatment.
How has the classification of pathogenic factors developed in TCM? Let me provide a brief explanation. The “Huangdi Neijing” (Yellow Emperor’s Inner Canon) actually classifies pathogenic factors, and its classification method is relatively simple and easy to grasp. It distinguishes between Yin and Yang. Yang pathogenic factors refer to wind and cold heat, which are external causes of disease. On the other hand, Yin pathogenic factors refer to dietary restrictions and emotional disturbances. Generally speaking, Yang pathogenic factors are external, while Yin pathogenic factors arise from internal changes in the body. This is a simple classification method for pathogenic factors in the “Neijing,” dividing them into Yin and Yang categories. During the Han Dynasty, Zhang Zhongjing further developed the classification of pathogenic factors from the “Neijing” into the Three Causes Theory. The Three Causes Theory divides pathogenic factors into three categories: internal causes, external causes, and other causes. Internal causes refer to the invasion of pathogens through the meridians into the organs; external causes refer to blockages in the limbs, nine orifices, and blood vessels; and other causes include sexual activity, injuries from weapons, and insect or animal bites. This is Zhang Zhongjing’s simple classification of pathogenic factors. In the Song Dynasty, Chen Wuze, also known as Chen Yan, wrote a book called “Three Causes and One Disease Syndrome Prescription Theory,” in which he further developed Zhang Zhongjing’s three pathogenic factors. He also classified pathogenic factors into three categories, which is known as the Three Causes Theory classification method. This classification method has continued to the present day, and we can see that all factors that can lead to diseases are generally encompassed by these three aspects.
Let’s take a look at how Chen Wuze classified pathogenic factors. He divided pathogenic factors into internal causes, external causes, and non-internal/external causes. Internal causes refer to emotional disturbances, which include the seven emotions: joy, anger, worry, thought, sadness, fear, and shock. These are changes in internal emotions that can lead to disease and are considered internal causes. Emotional changes leading to disease are a significant aspect of TCM. The second category is external causes, which refer to the invasion of the six excesses (Liu Yin). The six excesses refer to wind, cold, heat, dampness, dryness, and fire. These are six normal climatic phenomena in nature, referred to as the six qi. However, if the six qi exceed normal climatic changes or if the body’s righteous qi is insufficient, even normal six qi can become pathogenic. For example, in winter, most people do not catch colds, but if someone does, it indicates that their body is weak. Another situation is that in winter, when everyone is generally fine, if the temperature drops significantly, many people may catch colds. In this case, the six qi are normal but can still become pathogenic. The third category is classified as non-internal/external causes, which do not belong to either category. These include dietary issues, overexertion (including sexual activity), excessive labor, and mental strain. Additionally, injuries from falls or sharp objects, as well as insect bites, fall into this category. This is Chen Wuze’s classification of pathogenic factors in the “Three Causes and One Disease Syndrome Prescription Theory,” known as the Three Causes Theory.
In contemporary TCM, the classification of pathogenic factors has been adjusted based on the foundations laid by predecessors. How is it classified? It is divided into external pathogenic factors, including the six excesses and pestilential qi. The six excesses, as previously mentioned, are wind, cold, heat, dampness, dryness, and fire, which are six natural climatic changes that can lead to diseases. Of course, normal climatic changes are referred to as six qi, while those that can cause diseases are termed six excesses. Pestilential qi refers to infectious agents, such as those that caused SARS and Middle East Respiratory Syndrome, which are also classified as external pathogenic factors. External pathogenic factors include two aspects: the six excesses and pestilential qi. In ancient times, pestilential qi was also very severe, including cholera and the Black Death in Europe, which caused significant mortality. However, while Europe experienced millions of deaths, China never faced such high mortality rates, largely due to TCM’s ability to address these issues, whereas Europe had no means to manage them.
Next, we have internal pathogenic factors, which include three categories: the first category is the seven emotions, which refer to changes in emotional states that lead to discomfort. Each organ corresponds to specific emotional changes, generally categorized as joy, anger, worry, thought, sadness, fear, and shock. The second category is overexertion and excessive rest, where overexertion includes excessive labor and sexual activity, while excessive rest refers to being overly sedentary. The third category is dietary irregularities, which refer to improper eating and drinking that lead to diseases.
The third category is the pathological products that form as a result of disease, including dampness, phlegm, blood stasis, and stones. These pathological products arise from existing diseases and can lead to new diseases. For example, stones form as a result of an underlying condition, but they can also cause pain or obstruct the ureters, leading to kidney swelling and new causes of disease. Blood stasis also arises from diseases, but it can lead to symptoms such as numbness in the fingers or bleeding. This is referred to as a pathological product, which itself becomes a cause of harm and leads to further diseases.
The fourth category includes other pathogenic factors, such as external injuries, parasites, and drug-induced factors. Drug-induced factors include drug allergies, drug toxicity, and all adverse reactions from improper or inappropriate drug use, including the use of TCM, Western medicine, or other medications.
The fifth category includes iatrogenic factors, which refer to errors or excessive actions by healthcare providers that lead to disease due to incorrect treatment methods.
The sixth category includes congenital factors.
Currently, the classification of pathogenic factors in TCM includes four aspects: first, external pathogenic factors; second, internal pathogenic factors; third, pathogenic factors arising from pathological products; and fourth, other pathogenic factors. The entire theory of pathogenic factors revolves around these four aspects.
External Pathogenic Factors External pathogenic factors refer to those originating from the natural environment, primarily invading our bodies through the skin and respiratory system, including the six excesses and pestilential qi. Before understanding the six excesses, let’s first look at the six qi, which refer to wind, cold, heat, dampness, dryness, and fire. These six normal climatic conditions are the natural conditions for the growth of all living things and should not harm the human body. However, when the six qi become abnormal, either excessive or insufficient, it can be harmful. Excessive refers to situations where, for example, the normal summer temperature is around thirty degrees Celsius, but suddenly it rises to forty degrees, which many people cannot withstand. In this case, the six qi become harmful to the human body. Insufficient refers to situations where, for example, winter should be very cold, but suddenly the temperature rises to ten or twenty degrees, which is not cold when it should be. Abnormal six qi refers to either excessive or insufficient conditions, or qi appearing at inappropriate times. For instance, if warm weather appears in winter, it can be harmful to the body. Rapid changes in climate can also be harmful. Recently, in Jiujiang, the weather suddenly changed from very high temperatures to around ten degrees, and many patients I saw were suffering from colds and fevers, including my sister’s child, who had a fever of nearly forty degrees. This is an example of abnormal six qi, which can manifest in three states: first, excessive or insufficient; second, qi appearing at inappropriate times; and third, rapid changes in climate. All of these are considered harmful states of abnormal six qi, known as Liu Yin. Liu Yin refers to the six external pathogenic factors: wind, cold, heat, dampness, dryness, and fire. When the six qi become abnormal, they can lead to disease.
The six excesses have common characteristics that can lead to disease, specifically five major characteristics:
1. External pathogenic nature The six excesses are generally invasive, entering the body through the skin and respiratory system, causing disease. Since the six excesses are external factors, the diseases they cause are referred to as external diseases.
2. Seasonal nature The diseases caused by the six excesses have distinct seasonal characteristics. For example, in winter, the cold weather primarily leads to cold diseases; in spring, wind diseases are more common; in summer, heat diseases are prevalent; in late summer, damp diseases are more frequent; and in autumn, dryness diseases are more common. The six excesses exhibit clear seasonal characteristics, with different seasons being dominated by specific pathogenic factors. Of course, other disease factors may also appear, but each season has its corresponding main qi. In spring, it is wind; in summer, it is heat; in late summer, it is dampness; in autumn, it is dryness; and in winter, it is cold. This is the normal climate, and when this climate becomes abnormal, it transforms into pathogenic factors.
3. Regional nature The six excesses are closely related to the environmental conditions of the region. For example, the Jiangnan region is often humid and hot, leading to diseases caused by damp heat, while the northwest is drier, with dryness being the main qi, which can easily lead to diseases. In the northeast, where it is particularly cold, cold-related diseases are more common. The environment in which one lives can also lead to abnormalities; for instance, those living near water are more susceptible to dampness affecting their health.
4. Compatibility The six excesses can invade the body individually, such as cold, or they can combine in pairs or more to attack the body, such as wind-cold or damp-heat. They can invade the body together or separately, which is an important consideration.
5. Transformability The diseases caused by the six excesses can change under certain conditions. For example, a cold caused by exposure to cold can transform into a heat syndrome if it persists for too long.
The above are the five major characteristics of the six excesses: external pathogenic nature, seasonal nature, regional nature, compatibility, and transformability. For instance, a cold is classified under the six excesses, with the pathogenic factor being one or more of them. Western medicine, on the other hand, diagnoses a cold as a viral infection, gastrointestinal dysfunction, or bacterial infection. TCM does not focus on these; it primarily considers the climatic changes that lead to the disease, as viruses or bacteria exist in everyone, including tumor cells. The reason some people develop tumors while others do not is due to changes in their internal environment. Similarly, when the weather changes, some people catch colds while others do not. This is not solely due to the presence of viruses or bacteria. Western medicine may find that bacteria or viruses are proliferating, leading to disease. However, the real issue is that these pathogens coexist with the human body, and it is the interaction between the external environment and the internal environment that causes changes in the body’s internal environment, leading to disease. Therefore, TCM focuses on removing the factors that promote disease growth, allowing the patient to recover naturally. How does Western medicine treat this? By directly using antibiotics or antiviral medications to kill the pathogens. While this approach has its merits, the problem is that if the underlying environment is not changed, the pathogens will simply return. This explains why some children recover quickly after receiving injections for colds, while others may take ten days or longer to recover. The medications used in Western medicine, especially injections, are often cold in nature. If the cold is caused by a heat factor, using cold medications may not be effective. In fact, not treating the cold may yield better results, as the body has its own healing capabilities. This highlights the importance of understanding the underlying issues. As long as the factors that lead to the proliferation of bacteria or viruses are removed, the body can return to normal. Directly killing the pathogens is not the right approach, as they coexist with us in the same environment. We should aim to control their population rather than eliminate them entirely, as it is impossible to eradicate them completely. Moreover, killing them may also eliminate beneficial bacteria, which is detrimental to health. The presence of these microorganisms in our bodies serves a purpose, and they can be beneficial. This is why many products now focus on beneficial bacteria. Many people believe that consuming such products will improve their gastrointestinal health, but this is not always the case. If a healthy person consumes them, it may actually worsen their condition. If an unhealthy person consumes them, they may not survive. Western medicine has a rather unpleasant treatment method for chronic enteritis, which involves transferring processed feces from a healthy person into the intestines of a patient to restore a healthy microbial environment. TCM does not adopt this approach; instead, we adjust the intestinal environment through medications to restore balance in the microbial community.
Here, we have discussed the six excesses: wind, cold, heat, dampness, dryness, and fire. In TCM, there are also five pathological responses that clinically resemble the diseases caused by the six excesses. However, these are not external; they arise internally due to dysfunction of the organs and qi-blood. The five internal evils are: internal wind, internal cold, internal dampness, internal dryness, and internal heat. It is important to note that these internal evils differ from the six excesses. While they may present similar symptoms, one is external, and the other is internal. We will delve deeper into this topic in our future discussions on diagnosis.
Next, let’s examine the nature and pathogenic characteristics of the six evils: wind, cold, heat, dampness, dryness, and fire.
First, let’s look at wind evil. Wind is a natural climate phenomenon characterized by its invisible, flowing air. In the four seasons, spring is dominated by wind, and TCM associates wind with spring. Wind is a common phenomenon throughout the year, but it is most prevalent in spring. Wind evil refers to the abnormal state of wind that can lead to disease. In TCM, any external evil that possesses the characteristics of movement and dispersion is termed wind evil. The textbook defines wind evil as any external evil that causes disease and possesses the characteristics of movement and dispersion. What diseases are caused by wind evil?
First, its lightness and dispersive nature make it prone to attack the Yang areas of the body. Wind evil has the characteristics of lightness, upward movement, and outward dispersion, which can easily invade the body’s surface and cause sweating. Wind is a Yang evil, and its nature is to rise and disperse, which can harm the upper body, skin surface, and back. When wind evil invades the body, the symptoms and pulse characteristics include: 1) sweating; 2) aversion to wind; 3) floating and relaxed pulse, indicating that the disease is at the surface. Symptoms may include headache, dizziness, facial paralysis, stiff neck, and back pain.
Secondly, wind is characterized by its ability to move and change rapidly. This means that diseases caused by wind evil often exhibit symptoms that are mobile and changeable. For example, facial paralysis can occur suddenly after exposure to wind while riding a bus or train with the window open, or after exercising in an air-conditioned room. This is a classic example of wind evil. In the case of bi syndrome, there is a type known as xing bi, which is primarily caused by wind evil.
Thirdly, wind is proactive. Wind evil has the characteristic of causing movement, leading to symptoms such as dizziness, tremors, and facial asymmetry. For instance, when wind evil invades the body, symptoms may include dizziness, tremors, and facial drooping. In TCM, any condition that involves shaking or movement of the body is associated with wind, including both external and internal wind. Today, we are discussing external wind, while internal wind can also lead to similar symptoms.
Fourthly, wind is considered the leader of all diseases. It is widely recognized that wind evil can cause diseases on its own or in combination with other evils. Common external diseases include wind-cold, wind-heat, and wind-damp, all of which can occur.
In clinical practice, we assess the presence of external wind based on symptoms such as sweating, aversion to wind, and a floating and relaxed pulse. We also consider the characteristics of wind evil, including its mobility, rapid onset, and movement, to determine if wind evil is the cause of the disease.
That concludes today’s lecture. Next time, we will discuss other evils. The study of etiology is crucial, as it relates to our clinical diagnosis and treatment of diseases, making it particularly important for everyone to master this knowledge. Thank you for listening.
Dear students, good evening. Today we continue our study of the etiology in the “Foundational Theories of TCM” and will discuss the related content of cold evil.
Cold Evil
Cold refers to low temperatures. From a temperature perspective, it indicates a drop in temperature, which is primarily associated with winter. Cold weather is a normal climatic phenomenon in winter. Cold evil refers to the external evil characterized by cold and condensation in nature. In winter, we can observe this cold state. For example, water at low temperatures can freeze into ice. Therefore, cold can lead to symptoms of coldness, condensation, and contraction. In winter, we cannot tolerate cold evil, but it can occur in any season. For instance, in summer, there are two common scenarios: one is when it is extremely hot, and after sweating profusely, one consumes cold foods, such as ice-cold fruits, ice-cold watermelons, or cold drinks like cola or mineral water. In such hot weather, when the pores are open, consuming cold items can easily harm the body. The second scenario occurs after intense exercise, especially in summer, when one sweats profusely and then suddenly takes a cold shower or jumps into cold water, or sits in front of an air conditioner. This can easily lead to cold evil. We refer to diseases caused by external cold as external cold diseases.
External cold diseases can be broadly classified into two types: one is called shanghan (injured by cold), and the other is called zhonghan (internal cold). Shanghan refers to when cold evil harms the skin surface and obstructs the protective Yang. The Wei qi, which acts like a border guard, is the first line of defense against external evils. It has the function of blocking external pathogens. When cold evil invades the skin surface, Wei Yang fights against the cold evil. If the cold evil is strong, it can obstruct the Wei Yang at the skin surface. This situation is referred to as shanghan, which is commonly seen in colds. The second type is zhonghan, which refers to when cold evil directly affects the internal organs.
As mentioned earlier, summer can also lead to cold. For example, after sweating profusely, the pores open, and if one is suddenly exposed to cold air, the cold evil can obstruct the Wei Yang, causing the pores to close. This leads to symptoms such as high fever, which in modern terms is referred to as cold symptoms. This is classified as shanghan. Zhonghan refers to when one directly consumes cold foods or drinks, such as ice-cold water or ice-cold watermelon, which directly affects the Yang of the internal organs.
Both shanghan and zhonghan can occur in various situations, and we can broadly classify external cold into these two categories: one that directly harms the skin surface and one that directly affects the internal organs.
Another type is internal cold, which arises from a deficiency of Yang qi within the body, leading to a decrease in qi transformation and the accumulation of cold and damp substances. Generally, this results in symptoms of coldness in secretions and excretions. Internal cold is not caused by external evils but arises from deficiencies in the body’s Yang qi, which may be insufficient or excessively consumed.
Now, we are discussing the cold evil within the six excesses, which refers to external cold. Internal cold, as we discussed earlier, includes internal wind, internal cold, and internal dryness, which arise from dysfunction of the internal organs and qi-blood. Although they may present similar symptoms, the causes of their onset differ.
Next, let’s examine the nature and pathogenic characteristics of cold evil. Cold, from the perspective of Yin and Yang, is classified as Yin evil. Yin evils tend to harm Yang, and cold is a Yin evil that can easily damage Yang qi. Cold evil has a cold and freezing nature, which belongs to Yin. When cold evil enters the body, the Yang qi is dispatched to counteract it. If the cold is strong and the Yang qi is insufficient, the Yang qi may be harmed. Therefore, cold evil is a Yin evil that can easily damage our Yang qi, leading to a condition known as Yin excess causing Yang disease. This means that when the cold evil invades the skin surface, the Wei Yang will attempt to resist it. If the Wei Yang is suppressed by the cold evil, what symptoms will arise? Symptoms such as aversion to cold, absence of sweating, nasal congestion, and runny nose will occur. This is the condition we will later discuss in relation to the Ma Huang Tang syndrome. Recently, I have seen many patients with these symptoms, especially children with high fevers. Generally, high fevers are associated with the Wei Yang being suppressed. The surface temperature is regulated by the Wei Yang, which controls the opening and closing of the skin pores. When the Wei Yang is suppressed, the pores close, preventing sweating. When cold evil invades, the patient becomes particularly sensitive to cold, leading to symptoms such as aversion to cold and absence of sweating. The Wei Yang is also related to lung qi, and when lung qi is affected by cold evil, it becomes obstructed, leading to nasal congestion and clear nasal discharge.
Another condition is known as cold in the Taiyin. The Taiyin refers to the condition we will discuss in relation to shanghan lun (Treatise on Cold Damage). When cold invades the Taiyin, the spleen Yang is harmed. The spleen Yang is responsible for the transformation of food and drink, and when it is damaged, abdominal pain and cold sensations may occur. When Yang qi is suppressed, it cannot function normally, leading to symptoms of abdominal pain and vomiting or diarrhea.
These three conditions are very common in clinical practice. Cold evil can invade the surface, suppressing the Wei Yang, leading to symptoms such as aversion to cold, absence of sweating, and nasal congestion with clear discharge. This is a common condition treated with Ma Huang Tang. However, cold evil can also invade the internal organs, leading to other conditions, such as the Gui Zhi Tang syndrome. Recently, I have seen several children with sudden temperature drops. They may not exhibit obvious cold symptoms but may experience diarrhea. This can be accompanied by nausea and abdominal pain. When examining their tongues, they often have a white coating, indicating a cold condition. When checking their hands and feet, they feel cold. In such cases, we may use Fu Zi Li Zhong Tang or Li Zhong Tang, which can yield good results. This is different from the Western medications commonly used, which do not differentiate between Yin and Yang. Diarrhea and vomiting can be classified into two types: heat syndrome and cold syndrome. We will learn how to differentiate these in our future discussions on TCM diagnosis.
Cold evil has three main characteristics: it harms Yang, causes stagnation, and leads to contraction. When cold enters the body, it damages Yang qi, leading to Yang deficiency. This results in a decrease in the body’s ability to warm and promote movement, causing qi and blood circulation to slow down. This stagnation can lead to pain, as stagnation often results in discomfort. Therefore, cold evil is a particularly troublesome pathogenic factor.
Next, let’s discuss damp evil.
Dampness refers to the presence of moisture in the air. It is the main qi of the long summer season. The long summer refers to a specific time, which I will explain in detail when we discuss the twenty-four solar terms. Dampness is a normal condition, but when it leads to disease, it is termed damp evil. The external evil characterized by heavy, sticky, and downward-moving moisture is referred to as damp evil. When damp evil invades our bodies, it leads to what we call external damp diseases. There is also a type of internal dampness, which arises when the spleen’s function of transformation and transportation is impaired. When the spleen is weak, it cannot properly process the body’s fluids, leading to internal dampness. This internal dampness can make it easier for external dampness to invade the body. Understanding the relationship between internal and external dampness is important, but we do not need to complicate the issue.
Now, let’s examine the nature and pathogenic characteristics of damp evil. First, dampness is classified as Yin evil. In terms of Yin and Yang, damp evil belongs to Yin and can easily obstruct our qi mechanism and damage our Yang qi. The nature of dampness is similar to water, which is also Yin. Dampness can directly obstruct our qi mechanism. If dampness accumulates in the chest, it can lead to symptoms of chest tightness. If it accumulates in the spleen and stomach, it can cause abdominal distension and constipation. If it accumulates in the lower jiao, it can lead to symptoms of urinary difficulty. Damp evil can easily damage our spleen Yang, leading to spleen Yang deficiency and impaired spleen function. When the spleen’s function is impaired, symptoms such as diarrhea, short urination, and edema may occur. This is related to the functions of the spleen we discussed earlier.
Dampness is characterized by heaviness and turbidity. Heaviness refers to a sense of weight, while turbidity refers to something that is unclear or dirty. Damp evil is heavy and immobile, and when it invades our skin, it can obstruct our vital energy, leading to symptoms such as a heavy head, as if wrapped in a heavy towel. If the entire body is affected by damp evil, it can lead to a feeling of heaviness throughout the body. If dampness accumulates in the muscles, meridians, or joints, it can lead to symptoms of heaviness and pain in the limbs. This condition is known as zhuo bi, which is a type of bi syndrome primarily caused by damp evil. This is similar to conditions such as arthritis, rheumatoid arthritis, and cervical or lumbar spine disorders, which may fall under the category of bi syndrome. In contrast, the symptoms of wind bi are characterized by movement, while damp bi is characterized by fixed pain and heaviness.
Damp evil is also characterized by turbidity. Turbidity refers to the presence of impurities in excretions, such as urine and feces, which may appear unclear or dirty. For example, if a child comes to you with a cold and has excessive eye discharge, in addition to other symptoms of cold or heat, it is likely that damp evil is present, and you should consider adding herbs to resolve dampness. Symptoms of turbidity may include oily skin, excessive eye discharge, and a thick tongue coating. A normal person’s tongue coating is thin and white, while a person with dampness may have a thick, greasy coating. If the dampness is cold, the coating may be thick and white; if it is heat, the coating may be thick and yellow. The difference between cold and heat can be determined by color. If turbidity invades the skin, it can lead to conditions such as eczema, where small blisters may ooze a cloudy liquid. If it moves downward, it can lead to conditions such as excessive vaginal discharge in women or a feeling of dampness in the genital area. These are all manifestations of damp evil.
Damp evil is sticky and stagnant. The sticky nature of dampness refers to its tendency to adhere and cause stagnation. Symptoms caused by damp evil often present as sticky and uncomfortable, such as sticky stools or difficulty urinating. The presence of dampness can lead to a prolonged course of illness, as it tends to linger and can cause recurrent symptoms. For example, if dampness accumulates in the abdominal cavity, it can lead to conditions such as pelvic fluid accumulation, irregular menstruation, and excessive vaginal discharge. These conditions are often recurrent and difficult to treat.
Damp evil also tends to move downward and easily affects the lower parts of the body. This means that dampness tends to flow downward, affecting the lower body, including the feet and genital area. If a person is standing for long periods, edema may primarily occur in the lower extremities. If a person is lying down, the edema may be more pronounced in the buttocks. The nature of dampness is to flow downward, which is why it can easily affect the lower parts of the body. When treating dampness, we must consider how to expel it from the body. We will discuss how to manage dampness in different areas, such as the head, chest, abdomen, and lower limbs.
Next, let’s discuss dryness evil.
Dryness refers to a lack of moisture. It is the main qi of autumn. Dryness can lead to disease, which we refer to as dryness evil. The external evil characterized by dryness, clarity, and astringent properties is known as dryness evil. In autumn, we can observe the effects of dryness, as leaves fall from trees. This is a manifestation of the astringent nature of autumn. The nature of autumn is dry, astringent, and clear, and when dryness evil invades the body, it can lead to a series of dry symptoms, which we refer to as dryness disease.
Dryness can be classified into warm dryness and cool dryness. The nature of dryness evil is seasonal, typically occurring in autumn. The autumn qi can be divided into early autumn and late autumn. In early autumn, the weather is still warm, and dryness can combine with residual heat from summer, leading to warm dryness. In late autumn, as winter approaches, cold winds can combine with dryness, leading to cool dryness. When we encounter dryness evil, we must first determine whether it is warm or cool dryness, as this will influence our treatment approach.
The characteristics of dryness evil include its dry and astringent nature, which can easily damage our body fluids. Dryness leads to a lack of moisture, resulting in symptoms such as dry skin, itching, and cracked lips. During autumn, the skin may become dry, and the mucous membranes may also dry out. Symptoms of dryness can include dry skin, dry lips, and dry mucous membranes. The astringent nature of dryness means that when body fluids are depleted, the normal function of fluids is impaired, leading to symptoms such as dry cough with little phlegm, short urination, and constipation. This is a common manifestation of dryness evil.
Dryness evil also tends to harm the lungs. The lungs are delicate organs that prefer moisture and dislike dryness. The lungs open to the nose and are closely related to the skin. When dryness evil enters through the mouth, nose, or skin, it can damage the lungs, leading to symptoms such as dry cough with little phlegm, dry throat, and dry mucous membranes. In clinical practice, we often see patients with dry cough and little phlegm, which is indicative of dryness evil.
Next, let’s discuss fire evil.
Fire evil, also known as heat evil, refers to high temperatures, which are the opposite of cold evil. High temperatures are primarily associated with summer, and fire or heat is the main qi of summer. Diseases caused by fire or heat are referred to as heat evil or fire evil. The external evil characterized by the heat of fire is known as heat evil. In TCM, we have several concepts, including warmth, heat, and fire. Warmth is a concept we will discuss in detail when we cover warm diseases, so we will not delve into it now.
Heat and fire are similar but can be distinguished. Heat evil typically presents with systemic symptoms of fever, while fire evil often presents with localized symptoms such as redness, swelling, and pain, or sores in the mouth and tongue. In clinical practice, it is not necessary to differentiate between heat and fire, as both require heat-clearing treatments.
Heat and fire can be briefly explained. Heat is classified as an evil qi, while fire in TCM can refer to two types: one is known as Shao Fire, which refers to the normal Yang qi that has warming and transformative effects; the other is known as Zhuang Fire, which refers to the evil heat. These two concepts are entirely different. We will discuss these in detail when we cover the “Neijing.” In clinical practice, it is not necessary to differentiate between heat and fire, as both require heat-clearing treatments.
The characteristics of heat and fire evil include their Yang nature, which can easily damage body fluids and consume qi. Heat evil can lead to high fever, aversion to heat, red face, red eyes, and a rapid pulse. For example, the Bai Hu Tang syndrome is characterized by high fever, which is indicative of heat evil. Heat evil can easily damage our body fluids, leading to symptoms such as excessive sweating, thirst, and a preference for cold drinks. Patients may experience dry throat, dry lips, and short, dark urine. The “Neijing” mentions the concept of organ fire and dampness, where organ fire refers to heat and fire evil. Fire evil can damage our qi, leading to symptoms of qi deficiency, such as fatigue, weakness, and a lack of energy.
Heat and fire evil tend to rise, leading to symptoms in the upper body, such as headaches, ear ringing, sore throats, and mouth sores. Heat evil can also lead to internal wind and blood movement, causing symptoms such as convulsions, eye rolling, and even severe agitation or delirium.
Next, let’s discuss summer heat evil.
Summer heat refers to the hot qi of summer, which occurs between the summer solstice and the beginning of autumn. Summer heat is characterized by its seasonal nature, as it can only occur during this specific time. Summer heat can lead to diseases known as summer heat diseases, which are caused by the invasion of summer heat evil. Summer heat is primarily an external pathogenic factor and does not arise internally.
The characteristics of summer heat evil include its Yang nature, which is characterized by extreme heat. Summer heat can lead to high fever, red face, and a rapid pulse. It can also disturb the heart and lead to symptoms such as agitation, confusion, and even fainting, which is referred to as heat stroke.
Summer heat is also characterized by its ability to consume body fluids and qi. When summer heat invades the body, it opens the pores, leading to excessive sweating and the loss of body fluids. This can result in symptoms of qi and fluid deficiency, such as thirst, yellow urine, and fatigue.
Summer heat often combines with dampness, as the summer season is typically hot and humid. The combination of heat and dampness can lead to symptoms such as fever, irritability, and a feeling of heaviness in the limbs.
In summary, the six evils—wind, cold, heat, dampness, dryness, and fire—can be classified as follows: cold evil is Yin, while heat evil is Yang. Wind and dryness are considered Yang within Yin, while dampness is Yin within Yang. Summer heat is also classified as Yang. All Yang attributes can harm our body fluids, while all Yin attributes can affect our Yang qi, leading to a slowdown in qi and blood circulation. Yang evils can accelerate qi and blood circulation.
