Causes of Disease Theory - Etiology Theory
Seven Endogenous Factors
TCM emphasizes the
relation between diseases and mental activities. Emotional mental activities
are categorized as the seven emotional factors: joy, anger, sadness, worry,
grief, fear, and fright. They are the main pathogenic factors of endogenous
The seven pathogenic emotions are physiological reflections of the human mental
state or are induced by various environmental stimulation.
Under normal conditions these physiological phenomena will not cause disease.
However, if the emotions are too stressful and constant, or the patient is too
sensitive to stimulation, then they may induce acute and long-standing changes
which result in diseases. Pathogenic emotional factors are considered capable
of disturbing the functional activities of qi, for example, according to an
ancient saying, "Anger makes the qi rush upward, overjoy
makes the qi circulate slowly, grief consumes qi, fear cause qi to flow
downward, fright makes qi flow disorderly, overthinking leads to qi stagnation."
emotional factors also selectively damage certain zang or fu organs. For
example, anger injures the liver, overjoy injures the heart, grief and
melancholy injure the lung, overthinking injures the spleen, fright and fear
injure the kidney. Although emotional pathogenic factors respectively injure
the five zang, they are mainly related to the heart.
The Lingshu says, "The heart is the monarch of the
five zang and six fu organs.... Therefore, grief and melancholy also disturb
the heart, and a disturbance of the heart leads to the affection of the five
zang and six fu organs."
The seven clinically,
the pathological changes of internal organs caused by the seven emotional
factors are mostly seen in three of the zang organs, namely, the liver, heart,
- Shock or Fright (Causes
disturbance of the Qi)
Shock scatters the qi and affects both the Kidneys and the Heart and to a
certain extent, the Small Intestine. The Qi of the Heart is weakened
rapidly, leading to palpitations, breathlessness and insomnia, and
requires Kidney-Essence to support it. This puts a strain on the Kidneys,
and tonification of the Kidneys helps.
- Fear (Causes deceit of the Qi)
An appropriate sense of instinctive fear is necessary for survival. Fear
makes the Qi descend and affects the Kidneys. Excessive or prolonged fear
drains the Kidneys. It can also suppress Qi. Fear has a different impact
on adults and children. In children, fear causes Qi to descend, resulting
in nocturnal enuresis (bedwetting). In adults, fear tends to cause
Kidney-Yin deficiency. To some extent, Fear also disturbs the Heart,
leading to anxiety. The Kidneys have to be strengthened.
- Anger (Arouses ascend of Qi)
Anger affects the Liver and makes the Qi rise. Anger includes several
related emotions: resentment, repressed anger, irritability, frustration,
rage, indignation, animosity and bitterness. Sulking and depression are
also forms of anger (depression is blocked anger), frustration lies
between anger and depression. In depression due to repressed anger or
resentment, the tongue is dark red or red and dry. Anger is sometimes
necessary to exert one's authority. However, excessive and inappropriate
anger causes Stagnation of Liver-Qi or Liver-Blood, the rising of
Liver-Yang or Liver-Fire (which may cause Heart-Fire). These will cause
symptoms in the head and neck such as headaches (the most common symptom),
tinnitus, dizziness, red blotches in the front of
the neck, red face, red tongue and a bitter taste. Anger can also affect
the Stomach and Spleen, causing indigestion and other problems: this is
the pattern of Liver invading the Spleen or the Stomach. If depression
feels better after exercise, it is a Liver depression.
- Joy (Induces sluggishness of the
Joy slows down the Qi and affects the Heart. In general, joy is
beneficial. Being at peace and filled with happiness calms and slows the
Qi. Pleasure and excitement are other forms of joy. Pleasure is moderate
joy, and it allows the Qi to settle and sink. Excitement scatters the Qi
or slows it down. What are damaging are overexcitement and an abnormal
degree of mental stimulation, both forms of excessive joy. It is not,
however, an important or common cause of Heart disharmonies.
- Worry and Pensiveness (Causes
stagnation of the Qi)
Worry and Pensiveness means excessive thinking
(overthinking), excessive mental work and studying. This is very common in
our society, both in university students and people in intellectual
professions, and the problem is compounded if people eat quickly at work
or discuss work while eating. Obsessive thinking fraught with concern,
brooding and mental worry are also problems. All these forms of
pensiveness and worry knot the Qi and affect the Spleen, bringing an
accumulation of Dampness. Worry also affects the Lung, leading to anxiety,
breathlessness and stiffness of shoulders and neck. Worry may also be a
form of fear or anxiety.
- Sadness/Sorrow (Dissipates the Qi)
Sadness dissolves the Qi and affects the Lungs, leading to Lung Qi
deficiency, but it also affects the Heart, in time bringing on Heart Qi
deficiency. When the Lungs are overcome by sadness and grief, they are
weakened, and this leads to tiredness, breathlessness, depression or
crying. In women, this deficiency of Lung-Qi can lead to Blood deficiency.
Prolonged sadness can also lead to stagnation of Qi that in turn can
transform into Heart-Fire.
Six Exogenous Factors
TCM posits a uniquely
relative relationship between the zang-fu organs and tissues of the human body,
as well as between the human body and the natural environment. All are in a
relatively balanced state in order to maintain the body's normal physiological
function. When this balance is destroyed disease results. Through long term
clinical practice, the ancient Chinese realized that there are many factors
which may bring about imbalances in the human body and thus disease; climate
abnormalities, pestilence, emotional stimulation, injury by irregular diet or overstrain, trauma, insect-bited, etc., plus pathological
products of disease outcome, such as blood stasis, phlegm-humor, etc. All of
these contribute to imbalances within the human system.
The etiology of TCM used clinical manifestations as evidence, i.e., through the
analysis of symptoms and signs of a disease, one can find its causative
factors. This is technically termed "checking syndromes to find causative
factors of a disease." For our study of etiology, we must concern
ourselves with the properties of pathogenic factors and the characteristics of
how and why they cause disease.
TCM holds that the occurrence of a disease not only depends on exogenous
factors, but more importantly is decided by body resistance. TCM terms all
exogenous pathogenic factors as xie qi, while the body's is relatively weak,
xie qi will have an opportunity to attack and Suwen records, "If
a pathogenic factor attacks the body, then the zheng qi must be weak" Furthermore, "When
zheng qi exists in the interior, the pathogenic factor will be unable to
Therefore the invasion
of xie qi is due to the insufficiency of zheng qi, this is the root cause. Xie
qi is necessary condition for the occurrence of a disease. The development, transformation,
and prognosis of a disease depend on the forced balance of zheng qi and xie qi.
summer-heat, summer-fire, later summer-dampness, autumn-dryness, and
winter-cold are the six variations in the climate of the four seasons. They are
also known as the "six climatic factors" or the "six exogenous
The human body has the
ability to adapt to climatic variations. However, when bodily resistance is too
low to adapt to climatic changes or if there is an abnormal altering of the
weather which surpasses the body's adaptability, then the six climatic qi will
become pathogenic factors bringing about the occurrence of disease. Therefore
the climatic qi are all considered to be exogenous pathogenic factors.
Diseases which are not caused by exogenous pathogenic factors, but have
symptoms similar to the syndromes of wind, cold, summer-heat, dampness, and
dryness are termed internal heat, internal damp, internal dryness, and internal
fire. These endogenous pathogenic factors are the outcome of dysfunctions of
the zang and fu organs.
Pathogenic wind prevails in spring and is a common pathogenic factor of
the common cold. It causes diseases together with other pathogenic
factors, e.g., wind-cold, wind-heat, wind-damp, etc.
Wind is a yang pathogenic factor, characterized by upward flowing. When it
attacks the human body, it often affects the upper region first. For
example, if exogenous pathogenic wind causes a common cold, its symptoms
are headache, nasal obstruction, itching or sore throat, etc., which are
confined to the upper body. If pathogenic wind together with dampness
induces disease the symptoms are swelling of the eyes and face.
Wind is characterized by outward dispersion. If pathogenic wind attacks
the body, it may affect the defensive qi causing derangement in the
opening and closing of pores. The clinical symptoms are fever, sweating,
aversion to wind, etc.
Wind blows in gusts and is characterized by rapid change. In the Suwen it
says, "The wind is good at traveling and undergoes change
Diseases caused by wind are marked by migrating disease location and
symptoms that appear and disappear. Onset is abrupt and disappearance
hasty, e.g., migrating joint pain of bi syndromes, which usually involve
joint pains, and intolerable itching of urticaria.
Wind is characterized by constant moving. Pathogenic wind causes motor
impairment or abnormal motion of the trunk or limbs manifested by
convulsion, opisthotonos, spasm and tremor of the four limbs, and rigidity
of the neck. In the Suwen it says, "Predominant wind causes
symptoms characterized by movements."
Wind is liable to associate itself with other pathogenic factors.
Pathogenic wind is apt to be accompanied with cold, damp, or heat to
become wind-cold, wind-damp, or wind-heat pathogenic factors.
Wind may be also associated with some pathological products such as
phlegm, forming pathogenic wind-phlegm. The commonly seen symptoms caused
by exogenous pathogenic wind are known as shangfeng (wind damage). Main
clinical manifestations: fever, aversion to wind, perspiration, slow and
superficial pulse, dry and itching throat, cough, nasal obstruction and
discharge. These symptoms are due to damage by exogenous pathogenic wind
to the body surface and the lung. If exogenous pathogenic wind attacks the
skin and muscles, the wei (defensive) qi is
damaged and fails to defend the body surface. So perspiration and aversion
to wind occur. When wei qi fights against
exogenous pathogenic wind, fever arises. When the disease locates in the
exterior of the body, it causes sweating, thus the pulse is superficial
and slow. When exogenous pathogenic wind attacks the lung, its function
will become abnormal in the spreading and descending of qi and also brings
about a dysfunction of body fluid distribution. The clinical
manifestations of dry and itching throat, cough, nasal obstruction and
Pathogenic cold is prevalent in winter and as a yin pathogenic factor, it is likely to consume yang qi. It also has
the characteristics of contracture and stagnation.
These are described as follows:
- Pathogenic cold, as a yin
pathogenic factor, is liable to consume the yang qi of the body,
producing cold syndromes. If the pathogenic cold attacks the body surface
leading to a closing of the pores and obstruction of the flow of
defensive yang qi, it is manifested by the symptom of aversion to cold.
If pathogenic cold directly attacks the spleen and stomach it leads to
the injury of spleen yang qi causing dysfunctions of the whole digestive
process. The clinical manifestations are vomiting of clear water,
diarrhea, coldness and pain of the epigastric and abdominal regions, pain
relieved by warmth and aggravated by cold extremities, etc.
- Pathogenic cold is
characterized by contracture and stagnation. Invasion of pathogenic cold
may cause contracture of the blood vessels and tendons, and obstruction
of qi and blood circulation. This manifests as pain of a cold nature.
Pathogenic cold may also cause a common cold with symptoms of sore aching
joints and headache. Stagnation of cold in the liver channel leads to
hernia of a cold nature, coldness, pain, and swelling of the testis.
Pathogenic cold may also cause stomach ache, abdominal pain, etc.
Commonly seen syndromes caused by exogenous pathogenic cold are classified
into: cold damaging the skin and muscle and cold damaging the spleen and
Cold Damaging the Skin and Muscle: fever, aversion to cold, no sweating, tense
and superficial pulse, cough, asthma, nasal obstruction, nasal discharge, headache,
and aching body.
Fever, aversion to cold, no sweating, tense and superficial
pulse are caused by exogenous pathogenic cold that has blocked the
spreading of wei (defensive) qi. The lung is closely related to the skin and
hair. If exogenous pathogenic cold blocks the body surface and the wei qi can
not spread, then lung qi fails to disperse and descend, causing nasal
obstruction and discharge, cough, and asthma. Exogenous pathogenic cold will
also obstruct the channels, resulting in the stagnation of qi and blood, which
manifests as headache and aching body.
Exogenous Pathogenic Cold Injuring the Spleen and Stomach: vomiting, diarrhea,
borborygmus, and abdominal pain.
This group of symptoms is caused by an over-intake of raw and cold food or the
exposure of the abdomen to cold. As exogenous pathogenic cold injures the yang
qi of the spleen and stomach, then the functions of ascending and descending qi
by the spleen and stomach become disordered, causing a dysfunction of digestion
and absorption with the symptoms of vomiting, diarrhea, abdominal pain,
Summer-heat is the main pathogenic factor occurring only in the summer. It
is a yang pathogenic factor.
Its characteristics are described as follows:
- Summer-heat is a yang pathogenic
factor characterized by sweltering heat. If pathogenic summer-heat
attacks the body, the clinical manifestations are yang-heat, syndromes,
such as high fever, burning heat sensation of the skin, irritability,
forceful and rapid pulse, etc.
- Summer-heat consumes qi and
yin (body fluid), and is characterized by upward direction and
dispersion. Invasion of pathogenic summer-heat to the head region causes
dizziness, vertigo, and excessive sweating due to the abnormal opening of
the pores. Excessive sweating exhausts the qi and body fluid and
manifests as thirst with desire to drink, dryness of the lips and tongue,
constipation, yellowish and concentrated urine, etc.
- Pathogenic summer-heat often
combines with damp to cause diseases when the temperature and air
humidity are very high. If summer humid-heat attacks the body, the
manifestations are fever, heavy sensation of the head or even the whole
body, stuffiness and fullness of the chest and epigastric regions,
nausea, vomiting, abdominal distension, diarrhea, etc.
Pathogenic factors in summer are summer-heat, sun-stroke and summer
humid-heat. Main clinical manifestations of summer-heat: fever, excessive
sweating, irritability, thirst with preference for cold drinks, shortness
of breath, lassitude, general weakness, scanty and yellowish urine, rapid
and xu (weak) pulse.
Main clinical manifestations of sun stroke: dizziness and vomiting for
mild cases; sudden collapse, unconsciousness, profuse and cold sweating,
cold extremities, forceful and xu pulse for severe cases.
This group of symptoms are caused by strong sun
heat that internally affects the body qi activity leading to sudden
prostration of qi and body fluid.
Main clinical manifestations of summer humid-heat: fever, irritability,
stuffy chest, nausea, vomiting, anorexia, lassitude, loose stools,
yellowish urine, soft pulse, yellow and sticky tongue coating, etc.
The symptoms resulting from summer humid-heat invasion include the common
symptoms of summer-heat, such as fever, irritability, yellowish urine,
etc., and the symptoms caused by the obstruction of dampened qi
circulation, such as stuffy chest, nausea, vomiting and anorexia.
Furthermore, there are also the symptoms of internal dampness, such as
loose stools, soft pulse, sticky tongue coating, etc.
Damp is the main pathogenic factor causing disease in the late summer
since it is the most humid and rainy season.
It is a yin pathogenic factor with the following characteristics:
- Pathogenic damp stops the
functional activity of qi and leads to the injury of spleen yang. The
spleen functions best in a dry environment and is susceptible to
dampness, therefore pathogenic damp is liable to attack spleen yang. If
spleen yang is checked by pathogenic damp, it will cause a dysfunction of
transportation and transformation, and obstruct the functional activity
of qi. The following symptoms will occur: distension and fullness of the
epigastric and abdominal regions, anorexia, sweetish taste in the mouth,
loose stool, cold extremities, etc.
- Pathogenic damp is a
substantial pathogenic factor characterized by heaviness, turbidity,
viscosity, stagnation, and sluggishness. Invasion by pathogenic damp also
causes the symptoms of heaviness, distension and soreness of the trunk
and extremities. The secretions and excretions of the patient has foul and turbid features. The disease duration
- Pathogenic damp is
characterized by a downward direction. It is a yin pathogenic factor
which often attacks the lower portion of the body. The Suwen says, "When
damp attacks the body, it will affect the lower portion first."
Clinical manifestations are ulceration and edema of the lower
extremities, soreness of muscles, and joint pain of the lower limbs, etc.
Commonly seen syndromes caused by pathogenic damp are exterior damp, and damp bi. Main clinical manifestations of
exterior damp: fever, aversion to cold, fever not lowered after sweating,
heaviness of the body and head, sore aching of the four limbs, white,
thin and slippery tongue coating, soft and slow pulse. Those symptoms are
due to the injury of the body surface by pathogenic damp. When there is
obstruction by dampness, it damages the yang qi of the body, and blocks
the defensive qi. So fever and aversion to cold appear. Damp is
characterized by heaviness, turbidity, and stickiness. Thus fever is not
lowered after sweating. Moreover, other manifestations such as heaviness
of the body and head, sore aching of the four limbs, slippery tongue
coating, and soft pulse occur.
Damp bi is one of the bi syndromes due to excessive pathogenic damp, also
known as fixed by syndrome. Manifestations of damp bi: continued soreness
at one location, aching and heaviness of the joints, motor impairment,
and numbness of the skin. Bi syndromes indicate the obstruction by wind,
cold, or damp in the channels which damages the joints, skin, and
muscles. Damp is characterized by heaviness and turbidity, so heaviness
is fixed in the joints.
Dryness is the main pathogenic factor in autumn. Its characteristics are
as follows :
- Pathogenic dryness is apt to
consume yin, especially body fluids. Clinical manifestations are dryness
of the mouth, lips and nose, dryness of the tongue, dry, rough and
chapped skin, dry stool, etc.
- Pathogenic dryness is liable
to injure the lung. The lung is considered a tender organ which prefers
moisture, cleanliness, and descent. If pathogenic dryness attacks the
body from the mouth and nose, the yin fluid of the lung is likely to be
consumed. It may lead to the dysfunction of dispersion and descent, and
manifest as dry cough with scanty sputum, sticky mucus causing difficult
expectoration, or bloody sputum, etc.
Commonly seen syndromes caused by pathogenic dryness are cool dryness and
warm dryness. Main clinical manifestations of cool dryness: fever, aversion
to cold, headache, no sweating, dryness of the mouth and nose, dry skin,
cough with scanty or no sputum, dry white and thin tongue coating.
The symptoms of cool dryness are similar to symptoms caused by exogenous
pathogenic cold, but are accompanied with the symptoms of body fluid
insufficiency. Main clinical manifestations of warm dryness: fever, mild
aversion to wind and cold, headache, scanty perspiration, dry cough, or
cough with a small amount of sticky sputum, dry skin, thirst,
irritability, red tongue tip and sides, and dry scanty tongue coating.
The warm dryness syndrome is similar to the mild heat syndrome,
indicating that the body fluid is exhausted.
- Fire Heat or Mild Heat
Fire, heat, and mild heat are yang pathogenic factors. They are of the
same nature but differ in intensity. Fire is the outcome of extreme heat.
Mild heat is the least severe. These types of heat are sometimes termed
pathogenic fire-heat or pathogenic mild heat and are characterized by an
upward flaring and damaging of yin, with a tendency to disturb the blood
system. The following are some special features :
- Fire is characterized by
upward flaring. Clinical manifestations are fever, thirst, profuse
sweating, etc. If pathogenic fire travels inward to attack the mind, it
causes irritability, anxiety, insomnia, or even mania, unconsciousness,
and delirium in severe cases. Since pathogenic fire is likely to flare
upward, the clinical manifestations may be mostly on the head and facial
regions, such as a swelling and pain of the gums due to extreme stomach
fire, ulcers of the tongue and mouth, headache, and redness, pain and
swelling of the eyes.
- Pathogenic fire is liable to
consume yin fluid. Manifestations are fever, aversion to heat,
accompanied by thirst with desire for drinks (especially cold drinks),
dryness of throat and mouth, constipation, yellowish urine, etc.
- Pathogenic fire may disturb
the blood and cause extravasation. Mild cases will only have rapid pulse
due to acceleration of blood circulation. In severe cases, the blood
vessels and collaterals may be damaged, manifesting various hemorrhagic
symptoms, such as vomiting of blood (hematemesis), nose bleeds
(epistaxis), blood in the urine or stool, excessive menstrual flow, skin
eruptions, external boils and ulcers, etc. The common syndrome caused by
fire (heat) at the early stage is exterior-heat syndrome.
Main clinical manifestations: fever, mild aversion to cold, headache,
sore throat, thirst, yellowish urine, dry stool, red tip and sides of the
tongue, superficial and rapid pulse, etc. These symptoms are due to the
invasion of fire (heat) on the body surface which consumes body fluids.
This concludes the discussion of the effect of the six exogenous
pathological factors on the body. In general, these factors first damage
the body surface and then manifest an exterior syndrome with the symptoms
of fever and aversion to cold.