Aetiology and pathology of pain (Treatment of Pain with Chinese Herbs and Acupuncture) Part 1

Aetiology of pain

Exogenous factors


Wind is one of six exogenous factors, which is predominant in the spring but may also occur in any of the four seasons. When attacking the body, Wind is likely to combine with another of the pathogenic factors, such as Cold, Damp or Heat, etc., leading to retardation of Qi and Blood circulation. This causes blockage in the Zang-Fu organs, muscles, tendons, joints and channels, and pain follows.

Wind is classified as a Yang pathogenic factor because it has the characteristic of upward and outward movement. Because of this quality, it may easily invade the upper and superficial areas of the body, for instance the face, head, neck, shoulders, arms, chest, upper back, etc. So pain that is caused by Wind is found mostly in the top half of the body.

In nature Wind blows in gusts and is subject to rapid changes. Similarly, in the body it causes symptoms that are characterised by their migratory appearance. When a pain has no fixed location, but rather tends to wander around, this implies that its primary causative factor is Wind.


Cold is the predominant factor in winter. Although it can be seen in other seasons, in these its nature is not so severe. Cold invasion normally results from wearing too little clothing, exposure to Cold after sweating, being caught in rain, or wading through water in cold weather.

Cold is a Yin pathogenic factor and is likely to damage the Yang Qi of the Heart, Stomach, Spleen or Kidney. Cold includes both Exogenous and Internal Cold pathogenic factors; the former refers to Cold due to External invasion, and the latter to Cold due to Deficiency of Yang Qi. Exogenous Cold and Internal Cold may mutually influence and transform each other. For instance, Exogenous Cold may change into Internal Cold where there is prolonged persistence of the condition, resulting in damage to the Internal Yang Qi; conversely, a state of Internal Cold may easily induce invasion of Exogenous Cold.

Cold is characterised by stagnation and contraction, so Cold can easily slow the circulation of Qi and Blood. Thus, pain accompanied by a sensation of contraction, limitation of joint movement, aversion to cold and anhidrosis will be classified as being caused by Cold.

Cold may invade the body not only through the skin, mouth and nose, and drinking of cold liquids, but also through the uterus (e.g. after walking in the rain, or swimming or sex during menstruation). Moreover it can directly invade the muscles and joints, or even the Internal Zang-Fu organs if the Cold is very extreme, or the body very weak. The other opportunity for External Cold to invade is through the practice of walking barefoot. In Western countries, many people often do this inside the house, even on a cold floor, and in winter. Since the Kidney, Liver and Spleen channels all begin on the foot, External Cold may easily invade the Spleen, Kidney and Liver through these channels, especially the Kidney channel, which begins on the soles, in people who too frequently walk around barefoot on a cold floor.

Nowadays more and more homes and other buildings have air-conditioning to cool the place in the heat of summer. Consequently, many people now suffer from pain that becomes worse when they are sitting in their office equipped with air-conditioning, and they improve spontaneously once they leave the office and go out in sun. Thus they form a clear impression that cold places are bad and warm places are good for them, which is true. This is because our skin pores stay relatively open in the summer in order that we may sweat and keep our body temperature down. However, this also provides a very good opportunity for invasion of Cold, as the artificially cooled air can enter the body through the opened pores. Being characterised by contraction and stagnation, Cold may cause closure of the skin pores; this results in accumulation of Cold in the joints and muscles, so leading to pain due to Qi and Blood stagnation. Moreover, since the skin pores are now closed, Internal Heat cannot easily leave the body in sweat evaporation. So accumulated Cold can soon change into Heat, leading to symptoms of that aggravation, including redness, hotness, pain and swollen joints and muscles.


Invasion of Exogenous Damp is usually induced by humid weather, walking in the rain, living and working too long in humid places, or not changing out of one’s wet clothing after sweating. There is also a condition of Internal Damp, which is normally caused by disorder of the transportation and transformation functions of the Spleen and Stomach leading to formation of excessive water in the body. Exogenous Damp and Internal Damp often mutually influence each other in the causation of pain—that is to say, invasion of Exogenous Damp often attacks the Spleen and Stomach, while weakness of the Spleen and Stomach with formation of Damp may easily induce invasion of External Damp.

Damp is similar to water, which is characterised by heaviness. When it attacks the body, it causes pain accompanied by a feeling of heaviness of the head, limbs and body, together with a sense as though the body is bound. Where there is invasion of the skin and muscles by External Damp, this results in a blockage of the Clear Yang and disharmony of the Nutritive and Defensive Qi, which manifests as symptoms such as soreness of the limbs and joints, numbness of the limbs and muscles, and lassitude.

Damp is also characterised by viscosity and stagnation. Following on from this principle, pain that is caused by Damp is, generally speaking, stubborn and tends to be prolonged and intractable, compared with that caused by other pathogenic factors.

Damp is a Yin pathogenic factor and easily blocks Qi circulation and impairs Yang. When Damp accumulates in the Zang-Fu organs, joints, muscles or channels it may affect the ascending and descending of the Qi, leading to symptoms such as numbness of the skin and joints, and limitation of movement.


Dryness is predominant in autumn, and tends most often to impair the Lung, impeding the dispersal of Lung-Qi and causing stagnation, leading to symptoms such as throat and chest pain.

Dryness can also damage the Body Fluids, causing dryness of the skin, nose and throat. Furthermore, it may disturb and consume the Blood; then the blood vessels are not properly nourished resulting in narrowed vessels, and then the Qi and Blood stagnate, leading to painful skin.


Fire and Heat both indicate excessive Yang Qi, thus in most cases they are interchangeable, but there is still some slight difference between them. In terms of pathology. Heat is usually caused by Exogenous invasion, for instance Wind-Heat or Damp-Heat, whereas Fire is often caused by Internal disorders, for example flaming up of Heart-Fire or hyperactivity of Liver-Fire. In terms of the physiology, Fire has a proper function, which is to warm the Zang-Fu organs and promote Qi transformation and energy production; only if it becomes excessive does it become a kind of pathogenic factor causing overconsumption of energy in the body. Heat, in contrast, is simply a pathogenic factor.

Warmth is like Fire, with a physiological role but potentially pathogenic, and is also a kind of Heat, but milder. Of the three, Fire is the most severe, and Warmth the least severe, yet they all share similar characteristics. In practice, the terms Fire-Heat and Warmth-Heat are often used interchangeably.

Heat, a Yang pathogenic factor, is characterised by flaming up, burning and hotness. When it attacks the body, it may cause abnormal Qi and Blood circulation as well as injury to the Blood Vessels, causing pain accompanied by a burning feeling, a hot sensation, or redness. When Heat disturbs the Blood, the Blood circulation will be accelerated and the Blood Vessels can be damaged, causing swelling of the joints, muscles, or even bleeding, such as epistaxis, etc. Heat may also often disturb the Heart, which houses the Mind, causing restlessness and insomnia.

Like pathogenic Wind, Heat often attacks the top half of the body because of its characteristics of flaming up and moving in an upward direction, thus a combination of Wind and Heat causation is often seen. In most case of acute inflammatory joints and muscles in the upper parts of the body, Wind-Heat is the chief causative factor, thus the main treatment principle will be to dispel Wind and clear Heat.

Emotional factors

Pain is an indication of human suffering. This suffering may frequently be rooted in emotional distress as well as physical trauma.

Mental activities relating to emotion in TCM are classified into joy, anger, melancholy, meditation, grief, fear and fright, and are known as the seven emotional factors. The seven emotional factors differ from the six Exogenous factors in that they affect the Zang-Fu organs and the circulation of Qi and Blood, directly. For this reason, they are considered to be the chief causative factors for various kinds of pain. It is believed traditionally that different emotional factors tend to affect the circulation of Qi and Blood of various individual internal organs, resulting in retardation of Qi and Blood circulation, causing blockage to follow, and pain as the main clinical manifestation. The saying ‘anger injures the Liver, joy injures the Heart, grief and melancholy injure the Lung, meditation injures the Spleen, and fear and fright injure the Kidney’ (Yellow Emperor’s Classic of Internal Medicine: Simple Questions 1956, p. 17) is an expression of relationship between the different emotional factors and each of the internal Zang-Fu organs.

Another saying from ancient medical texts is: ‘anger causes the Qi to rise, joy causes it to move slowly, grief drastically consumes it, fear causes it to decline, fright causes it to be deranged, and worry causes it to stagnate’ (Yellow Emperor’s Classic of Internal Medicine: Simple Questions 1956, pp. 80-81). From this it can be seen clearly that abnormal Qi and Blood circulation is one explanation for the occurrence of pain.

In clinical practice, it has often been observed that in some patients suffering with pain their pain is aggravated or alleviated by their emotional state. Take shoulder pain, for instance: if the biceps muscle (which is in the area of the Lung channel) is involved, it is sometimes found that such patients either have suffered much grief in the past or do so at present and usually admit that when their feelings of grief recur their shoulder pain worsens. Since the Lung and Large Intestine share a pair of channels and collaterals, if the Lung channel is blocked the Large Intestine channel can also become impaired, leading to shoulder or arm pain. In this case, the points nearby (such as LU-2 Yunmen, LU-3 Tianfu, LU-5 Chize or LU-6 Kongzui) are usually found to be tender. There may also be tenderness found around LI-4 Hegu, LI-9 Shanglian and LI-10 Shousanli, as well as LI-Il Quchi. Another example is patients suffering from lower back pain, some of whom may have aggravation of pain with particular emotional states, especially anger and stress. This kind of pain can also radiate to the inguinal region, and even to the interior aspect of the leg along the Liver channel, and consequently along the Gall Bladder channel also. Conversely, if the Gall Bladder channel is primarily affected, there could be impairment of the Liver channel as well. For instance, disc herniation between L4 and L5 often manifests as pain along the Gall Bladder channel, which sometimes refers to the inguinal region. In this case, anger or stress may play a very important role in the aggravation of the low back pain.

The causation of pain by excessive emotional activities is basically described in following sections.


These often disturb the physiological functions of the Heart, leading to retardation of Qi and Blood circulation in the Heart, causing chest pain, heart pain, and pain in the shoulder along the Heart channel; palpitation and insomnia also occur. A point of distinct tenderness is typically found along the Heart channel, especially at HT-3 Shaohai. Needling or even simple massage at this point can greatly relieve the chest, heart or shoulder pain.

Anger may cause dysfunction of the Liver, impeding its free flow of Qi, and leading to a condition of stagnation of Liver-Qi. In TCM anger in fact includes other emotions such as frustration and irritation, which also may cause disharmony of the Liver leading to stagnation of Liver-Qi. Liver-Qi stagnation gives rise to symptoms such as headache, hypochondriac pain and distension, depression, abdominal pain and distension, and low back pain. Such pain is characterised by being wandering and distending in nature, or intermittent, or fluctuating in intensity and location. Another characteristic is that the pain often occurs at times of strong emotion, especially anger, stress, nervousness or irritability.

Stagnation of Liver-Qi can also be traced to emotions arising from being mistreated during childhood (e.g. from being beaten, lack of love, limitation of freedom, sexual abuse, or difficulties with friends, parents, brothers or sisters). Stagnation of Liver-Qi originating in childhood may cause either conscious or subconscious blockage in the Liver, bringing on pain at a later date due to severe psychological and physiological problems.

The Liver is in charge of promoting Qi circulation both in the Liver itself and generally in the body. If there is Liver Qi stagnation, the Liver fails to maintain the free flow of Qi in the channels, muscles, and Zang-Fu organs as well. The consequences can be summarised as follows.


Because Qi is the commander of the Blood, Qi circulation leads to Blood circulation, and Qi stagnation causes Blood stagnation. Hence, Liver-Qi stagnation may finally bring about Blood stagnation, which results in a more severe pain, stabbing pain, or a constant pain with fixed location.


Prolonged Liver-Qi stagnation may also generate Fire, leading to flaming up of Liver-Fire, and symptoms such as headache, painful ears or painful eyes. A further development of this is hyperactivity of Liver-Yang, which can develop into internal stirring of Liver-Wind which causes severe headache, facial pain, neck pain, or stiffness of the neck.

If Liver-Fire persists it eventually can consume the Yin of the Liver, and even the Yin of the Kidney, resulting in failure of the Liver and the tendons to be nourished, and consequently in hypochondriac pain, tiredness, headache, muscle pain with cramp, dizziness, constipation, or abdominal pain.

When there is Liver-Yin deficiency, the Yang of the Liver will not be properly controlled, leading to hyperactivity of Liver-Yang; thus a mixture of Deficiency and Excess appears, which is not easy to deal with.


Bile is stored in the Gall Bladder, but its formation depends on the normal circulation of Liver-Qi. Once Bile is formed it must be distributed, with the help of Liver-Qi, into the Stomach and Intestines in order to help the digestion. However, if there is Liver-Qi stagnation there is either insufficient Bile secretion or abnormal bile distribution, so the digestion is disturbed, leading to stomach pain, belching, abdominal pain and distension, or constipation, etc. resulting from the dysfunction of the the digestive action of the Stomach and Intestine.


To produce Qi and Blood, the Spleen also needs the help from the Liver, as the latter maintains the free circulation of Qi not only in the Liver itself, but also over the whole body. Without Liver-Qi circulation, the Spleen would find it impossible to maintain its physiological function of transportation and transformation. Where there is stagnation of Liver-Qi, there could also be stagnation of Spleen-Qi. In this situation the Spleen cannot transport and transform food and water, and excessive water forms in the body, causing pain resulting from blockage of the Zang-Fu organs, channels, joints and muscles by Damp-Phlegm. Moreover, Liver-Qi stagnation often attacks the Spleen, leading to formation of so-called disharmony between the Liver and Spleen; this manifests in symptoms such as abdominal pain, loose stool or diarrhoea when nervous, or flatulence.


Liver-Qi stagnation is one of the direct causes of stagnation of circulation in the channels generally. In addition, stagnation of Blood and formation of Damp-Phlegm may also impede circulation in the channels; in such cases blockage occurs in the channels, followed by numbness, pain, diminished skin and muscle sensitivity, joint pain, etc.


These may cause dysfunction of the Lung, leading to Qi and Blood stagnation in the Lung and its channel. The symptoms of this include: chest pain, shoulder pain and throat pain, accompanied by cough, difficulty in breathing out, and a sensation of oppression across the chest area.

Dysfunction of the Lung may also cause shoulder pain, which occurs in the interior aspect of the shoulder, down the biceps muscle. Patients with such pain often admit that they might have experienced enormous grief prior to the onset of the pain. Points of tenderness along the Lung channel may be found at LU-I Zhongfu, LU-2 Yunmen, LU-3 Tianfu, LU-4 Xiabai, LU-5 Chize and LU-6 Kongzui.


This brings about Qi stagnation in the Spleen and Stomach, leading to dysfunction in the functions of transportation and transformation. This may cause the following four kinds of pathological changes.


Types of pain include epigastric pain, abdominal pain and distension with fullness, and pain that is worsened after eating.


This may cause failure to nourish the Zang-Fu organs, muscles, joints and channels.


Damp-Phlegm may block the Zang-Fu organs, joints, muscles and channels. Slowing the circulation of Qi and Blood, and causing pain, swelling and numbness of muscles and joints accompanied by a heavy feeling, limitation of movement and lassitude.


If Damp-Phlegm accumulates in the body then it is vulnerable to External Damp invasion, leading to aggravation of the pain, and complications in treatment.


Fright or shock gives rising to a failure of the Kidney to distribute the Kidney-Essence, which in normal circumstances produces the Marrow and nourishes the Bones. Weakness of the knees and lower back, dizziness, tinnitus and other symptoms can be the result. Of course, this type of lower back pain is not often seen in practice.

From the above account, it can be concluded that it is insufficient simply to use the method of circulating the channels to treat the various kinds of pain associated with certain emotions. It is also necessary to use the method of smoothing the emotions and regulating the organs.

Miscellaneous pathogenic factors


Food is the main material from which human beings receive energy, Qi and Blood; even Kidney-Essence needs to be nourished continuously from food. Inappropriate food intake comprises three aspects: overindulgence, insufficiency and intake of unsanitary food.

In industrialised countries, insufficient food intake normally is now seldom seen; overindulgence or intake of unsuitable or unsanitary food, however, is much more common. Generally speaking, insufficient food intake causes pain of the Deficient type resulting from failure to nourish the body, joints, muscles or Zang-Fu organs. In contrast, overindulgence and intake of unsanitary food often cause pain of the Excessive type resulting from blockage of the Zang-Fu organs, meridians, joints and muscles from Qi and Blood stagnation or Phlegm and Damp accumulation.


Raw food, cold food and cold water are Yin in nature. Generally speaking, Westerners eat far fewer vegetables than do Chinese people; moreover, many like to eat them raw, whereas Chinese people usually don’t like to eat their vegetables uncooked, but rather steamed or oil-baked, for instance. In addition, in hot weather Westerners prefer to drink cooled water from the refrigerator, or even with a few pieces of ice in the glass. This is not good for the health, according to TCM, because the Spleen organ ‘dislikes’ cold and raw food, as it needs to spend more energy to first warm it before digesting it, compared with warm or cooked food. If Spleen, day after day, year after year, has to do this extra work, the Spleen-Yang eventually becomes impaired, causing inhibition of its functions of transportation and transformation, and Phlegm-Damp develops as a consequence. Once this is formed, it may spread throughout the body together with the Qi and Blood, causing, for instance, blockage in one of the Zang-Fu organs, or the joints, muscles or channels; Qi and Blood circulation are impeded and, as a result, pain occurs. Overeating of raw or cold food and drinking cold water is a common cause of the formation of Cold-Damp, or Cold-Phlegm.

One more fact that needs to be mentioned is that inappropriate use of some medicinal drugs or herbs may also sometimes cause damage of the Spleen and Stomach leading to formation of Cold Damp-Phlegm. In clinical practice it is often seen that some patients, and especially children, suffering from Spleen-Yang deficiency have been taking antibiotics for too long or too often frequently. People who often use Heat-clearing herbs for their Heat syndromes may also eventually damage their Spleen and Stomach-Yang. AU these habits finally bring about dysfunction of the processes of digestion, transportation and transformation of the Spleen and Stomach, resulting in the development of Cold-Damp.

Addition of too much salt to food is another important pathogenic factor. This practice damages the Kidney. A certain amount of salt intake in the food is necessary for the functioning body, especially for the Kidney, because according to TCM a salty taste goes into the Kidney and can disperse Qi and promote defecation. However, overuse of salt will impair the physiological function of the Kidney—that of Qi transformation and water metabolism. As a result, Excessive Water accumulates in the body, leading to pain in the limbs and body, oedema, and a feeling of heaviness in the body generally.

Next post:

Previous post: