This issue covers: 1. External Heat
2. Internal Heat
3. Treatment of Internal Heat
4. Summary of External Six Excesses
5. Summary of Internal Five Evils
1.External Heat
Warmth, heat, summer heat, and fire all belong to the fire element; these four are similar in nature but differ in name. The three terms—warmth, heat, and summer heat—are generally used for systemic diseases caused by fire evil, differing only in the degree of heat, with warmth being the least intense and summer heat the most intense. Fire is typically used for local pathological changes caused by fire evil.
Fire is a Yang evil, characterized by heat, which scorches the body’s Yin fluids and depletes the body’s vital energy. Any factor that can cause such harm to the body is considered a fire evil in TCM, whether it is physical, chemical, or biological.
Fire evil as a disease first harms Yin fluids. On one hand, fire evil directly scorches body fluids; on the other hand, fire evil causes sweating, leading to the leakage of fluids. Fire evil as a disease subsequently depletes Qi. Intense fire evil can directly consume the body’s righteous Qi, as stated in the Huangdi Neijing: “Strong fire consumes Qi”; fire evil harms Yin fluids, and as Yin fluids are depleted, Qi is also consumed.
When fire evil enters from the outside, it initially harms the surface and the Yin fluids of the lungs, which can manifest as fever, sweating, aversion to heat, sore throat, red and painful tongue edges, and a rapid pulse.
If fire evil penetrates deeper, accumulating within the body, or if the invading evil is a highly intense heat or summer heat, it can directly harm the internal Yin fluids, leading to high fever, sweating, extreme thirst, and a surging rapid pulse. If Yang heat is excessive, a large amount of Yin fluids will be consumed, and Qi will also be depleted, resulting in symptoms of Qi deficiency such as fatigue, shortness of breath, and reluctance to speak; in severe cases, there may be a complete loss of fluids leading to coma. Heat disturbs the spirit, with mild cases causing restlessness and insomnia, while severe cases may lead to agitation, confusion, or delirium.
When fire evil penetrates deeper, it stirs the Qi and blood, accelerating their flow, which can lead to extreme heat generating wind, clinically presenting as high fever, confusion, convulsions, upward eye movement, and opisthotonos.
Many TCM theoretical texts explain extreme heat generating wind as fire evil harming body fluids, leading to muscle spasms due to lack of nourishment and moisture in the tendons. Zou Shizhen believes this is an explanation of Yin deficiency generating wind, rather than extreme heat generating wind. Extreme heat generating wind occurs because fire evil enters the body, stirring the Qi and blood, and when their flow accelerates to a certain degree, wind phenomena appear. Many children may exhibit wind phenomena when they first develop a high fever without significant sweating; this should not be overlooked simply because body fluids have not been harmed.
As long as there is a temperature difference, wind will be generated; both cold evil and heat evil can trigger internal wind. Internal wind caused by cold evil is often milder or chronic, and its clinical manifestations are not as severe as those caused by heat evil, nor is internal wind from heat evil as common. With the fading of TCM theories, the understanding of the essence of internal wind has gradually diminished in the TCM community. Many TCM theoretical texts merely summarize the limited clinical experiences of predecessors, thus rarely mentioning cold extreme generating wind, focusing only on heat extreme generating wind. It is crucial to note that wind can be generated not only by heat extremes.
If fire evil further penetrates, disturbing the blood, it can lead to blood heat causing abnormal bleeding symptoms such as hemoptysis, epistaxis, hematochezia, hematuria, and skin purpura.
When fire evil is localized, the affected area will exhibit redness, swelling, heat, pain, suppuration, and necrosis. If fire evil is too intense, even if localized, it can cause systemic symptoms such as fever and thirst.
Many TCM theoretical texts categorize summer heat as a separate entity, thus identifying six external evils in total, known as the Six Excesses. In reality, summer heat is a type of fire evil, with the greatest heat, manifesting initially as high fever, flushed face, profuse sweating, fatigue, and even sudden fainting.
Colds occurring in summer often present with dizziness, chest tightness, nausea, and vomiting, differing from symptoms in other seasons, especially winter. What is commonly referred to as heat stroke is not actually caused by summer heat, but rather by cold or damp evil; it is simply that in summer, the impact of cold evil on the body is not as significant as in other seasons, thus symptoms like nasal congestion, runny nose, body aches, and fever do not appear, making it suitable to use Huo Xiang Zheng Qi San to dispel dampness and drive away cold.
2.Internal Heat
Internal heat refers to a pathological state characterized by fever or localized redness, swelling, and pain, or burning of Yin fluids due to certain causes, which is extremely common in clinical practice.
There are numerous viewpoints regarding internal heat in TCM theory, many of which are erroneous. Some clinical mistakes in TCM arise from misunderstandings of internal heat, such as the long-term use of Long Dan Cao Pian to clear internal heat leading to kidney failure. This is not an issue with the medicine itself, but rather a misuse of the medication.
Many foundational TCM theoretical texts are vague in their discussions of internal heat. First, they do not clarify the essence of internal heat; second, they do not explain the process of internal heat formation; third, they lack a reasonable classification method for the types of internal heat, merely listing a few types without comprehensive coverage.
Zou Shizhen’s basic viewpoint on internal heat: There is no absolute excess of fire within the human body, only a relative excess of fire. The essence of internal heat is the body’s own life fire, which arises from a lack of restraint or inability to flow and transform smoothly. Simply clearing heat to extinguish internal heat is akin to gradually extinguishing one’s own life; as long as life persists, the fire does not extinguish.
The body’s heat production system continuously generates heat, which is the body’s fire. This fire originates from the center of the body, circulates throughout, gradually intensifying, warming every part of the body, and is finally dissipated through the body’s heat dissipation system to maintain internal thermal balance. The body’s fire is the driving force of life; without this fire, the body becomes cold, and all life activities cease. In the absence of external fire evil invasion, the body’s own fire will not have an absolute excess leading to internal heat symptoms; it is only a relative excess of fire.
Relative excess includes two layers of meaning: first, fire is Yang, constrained by the body’s Yin; if the body is Yin deficient, Yang is relatively excessive compared to Yin, and without Yin’s restraint, internal heat phenomena occur; second, when the body’s fire cannot flow smoothly within, accumulating together, it leads to localized excess fire.
Therefore, any factor that can cause Yin deficiency or prevent the smooth flow of fire can lead to internal heat.
Yin deficiency is often related to long-term consumption. Factors that hinder the smooth flow of fire include external invasion of cold, damp, or dry evils, which affect the body’s Qi and blood circulation from the surface inward; food stagnation, parasitic accumulation, etc., which obstruct the circulation of Qi and blood in the gastrointestinal tract; phlegm and blood stasis affecting the circulation of Qi and blood in the affected area; emotional factors influencing Qi and blood circulation according to their five-element characteristics; and insufficient Qi in the body, which cannot promote normal circulation of Qi and blood. When Qi and blood circulation is abnormal, the internal fire cannot flow smoothly throughout the body, leading to the accumulation of internal heat at obstructed sites.
3.Treatment of Internal Heat
Despite the various theories of internal heat in traditional TCM, their essence is fundamentally the same. Treating internal heat cannot solely involve clearing heat; it is essential to identify the cause of internal heat and address it to truly resolve the issue. The essence of internal heat is the life fire of a person; if the cause of internal heat is not resolved and only heat is cleared, although symptoms of internal heat may initially disappear, once the medication is stopped, the life fire will again accumulate into internal heat. This cycle of accumulation and clearance continuously depletes the body’s Yang energy, akin to chronic self-harm, ultimately leading to kidney failure.
4.Summary of External Six Excesses
The external evils that affect function and cause disease, regardless of how many factors there are, can be categorized into five types based on the nature of the changes they induce in the body’s dynamic balance. These five types of evils can enter the body individually or in combination, affect different parts, or vary in strength while sharing the same nature, leading to countless different diseases.
However, as long as one understands how these five major types of pathogenic evils induce changes in the body and what kinds of changes they cause, one can determine the nature of the pathogenic Qi based on the patient’s clinical manifestations and formulate an appropriate treatment plan. This methodology in TCM is highly significant for treating newly emerging bacterial and viral epidemics, allowing for the development of effective treatment plans even before the pathogen is identified.
5.Summary of Internal Five Evils
The internal five evils are not actually causes of disease but rather five pathological states presented by functional diseases of the human body. In treating internal five evils, TCM practitioners must consider the reasons behind each patient’s internal evils; only by addressing the causes of the five evils can true resolution be achieved. If one simply uses wind-dispelling herbs for internal wind, heat-clearing herbs for internal heat, damp-dispelling herbs for internal dampness, Yin-nourishing herbs for internal dryness, and Yang-warming herbs for internal cold, it often fails to cure the patient and may even harm their health.