Causes of disease in Chinese medicine: external and internal
Traditional Chinese medicine groups the causes of disease into three categories: external (the six climatic factors, such as wind, cold or dampness), internal (the seven emotions when they are intense or prolonged) and neither internal nor external (diet, overwork, injuries and other habits). It is a traditional model, distinct from the etiology of modern medicine.
Key points
- TCM traditionally classifies the causes of disease as external, internal and neither internal nor external.
- The six external factors are wind, cold, summer heat, dampness, dryness and fire.
- The seven emotions are only considered pathogenic when they are very intense, sudden or prolonged over time.
- Diet, overwork, a sedentary lifestyle and injuries make up the third group of causes.
- Phlegm and Blood stasis are described as pathological products that can cause new imbalances.
In traditional Chinese medicine (TCM), disease appears when the balance between the body and its environment, or between the body's different functions, is broken. The study of what causes that imbalance is called bing yin (病因, bìng yīn), literally "cause of disease". Throughout its history, the Chinese tradition has organized these causes into a classical system of three groups, known as the theory of the three causes (三因, sān yīn). Knowing it helps to understand why a TCM practitioner asks about the weather, emotions or diet when assessing a person.
What are the three categories of causes?
The traditional classification distinguishes:
- External causes (外因, wài yīn): climatic factors that, according to the theory, enter the body from outside.
- Internal causes (内因, nèi yīn): emotions that directly disturb the function of the organs.
- Neither internal nor external causes (不内外因, bù nèi wài yīn): lifestyle habits, diet, injuries and other factors.
Alongside them, TCM pays close attention to each person's constitution and the strength of their defensive Qi (卫气, wèi qì). Traditionally, a pathogenic factor is considered to cause disease only when it overcomes the body's capacity to defend itself.
The six external factors: wind, cold, heat, dampness, dryness and fire
Under normal conditions, climatic changes are called the "six qi" (六气, liù qì). When they are excessive, arrive out of season or find a weakened body, they become the six excesses or six evils (六淫, liù yín).
| Factor | Hanzi and pinyin | Nature | Traditional characteristics |
|---|---|---|---|
| Wind | 风, fēng | Yang | Appears and changes quickly; affects the upper part of the body; combines with other factors |
| Cold | 寒, hán | Yin | Contracts and blocks; produces pain, stiffness and a feeling of cold |
| Summer heat | 暑, shǔ | Yang | Seasonal; produces intense heat, sweating and exhaustion |
| Dampness | 湿, shī | Yin | Heavy and sticky; causes swelling, heaviness and a slow course |
| Dryness | 燥, zào | Yang | Damages fluids; produces dryness of the skin, mouth and throat |
| Fire | 火, huǒ | Yang | Rises; produces redness, fever, thirst and restlessness |
It is important to understand that these terms also describe symptom patterns. A "dampness" picture does not require having been in a damp environment: the name describes how the symptoms manifest. The yin and yang classification is based on the theory of yin and yang.
The tradition also distinguishes between these external factors and the so-called "internal" factors with the same name, such as "internal wind" or "internal dampness", which arise from imbalances of the organs themselves.
The seven emotions as an internal cause
The seven emotions (七情, qī qíng) are joy, anger, worry, excessive thinking, sadness, fear and fright. The tradition insists that they are normal, healthy reactions. They are only considered a cause of imbalance when they are very intense, sudden or prolonged over time.
| Emotion | Hanzi | Associated organ | Traditional effect on Qi |
|---|---|---|---|
| Anger | 怒, nù | Liver | Makes Qi rise |
| Excessive joy | 喜, xǐ | Heart | Scatters Qi |
| Excessive thinking / worry | 思, sī / 忧, yōu | Spleen (and Lung) | Knots or stagnates Qi |
| Sadness | 悲, bēi | Lung | Consumes Qi |
| Fear | 恐, kǒng | Kidney | Makes Qi descend |
| Fright | 惊, jīng | Kidney and Heart | Disorders Qi |
These associations with the Zang Fu organs derive from the theory of the five elements. Modern medicine also recognizes that chronic stress and intense emotions can influence health, although it explains this through different mechanisms, such as the nervous, endocrine and immune systems.
Neither internal nor external causes: habits and lifestyle
This group brings together factors related to the way we live:
- Diet: eating too much or too little, at irregular hours, or overindulging in cold, fatty or very spicy foods or alcohol. The tradition places great importance on the Spleen and the Stomach, as explained in Chinese dietetics.
- Excessive physical or mental work, as well as too much rest and a sedentary lifestyle.
- Excessive sexual activity, which is traditionally associated with depletion of Kidney Essence.
- Injuries, burns, stings and wounds.
- Parasites and poisoning.
Pathological products: phlegm and Blood stasis
TCM also describes substances that form as a consequence of an imbalance and that, in turn, become new causes of disease. The main ones are phlegm (痰, tán), which results from poor transformation of fluids, and Blood stasis (瘀血, yū xuè), which arises when circulation slows down. Both hold a central place in traditional clinical reasoning.
How to interpret this model today
The theory of the causes of disease is a traditional way of organizing clinical observation and is consistent with the rest of the TCM system. However, it is not equivalent to the etiology of modern medicine, which identifies specific causes such as infections, genetic disorders or degenerative processes. Some recommendations derived from this model, such as watching your diet, resting or managing stress, coincide with general health advice; other interpretations lack scientific support.
For this reason, if you have persistent, intense or worsening symptoms, the right step is to see a healthcare professional for a medical diagnosis. The traditional analysis of causes can complement, but never replace, that assessment. In practice, the causes identified are integrated with the eight principles to define a pattern.
Frequently asked questions
What are the causes of disease according to Chinese medicine?
Traditional Chinese medicine groups the causes into three categories. The external ones are the six climatic factors: wind, cold, summer heat, dampness, dryness and fire. The internal ones are intense or prolonged emotions. The third group includes an inappropriate diet, too much work or rest, excessive sexual activity, injuries and parasites. It is a traditional framework, not a current medical classification.
Can emotions cause disease according to Chinese medicine?
According to tradition, emotions are part of normal life and are not harmful in themselves. They are considered a cause of imbalance when they are very intense, sudden or long-lasting. Each emotion is associated with an organ: anger with the Liver, worry with the Spleen and fear with the Kidney. Modern medicine also recognizes the relationship between stress and health, although it explains it through other mechanisms.
What do 'wind' or 'dampness' mean in Chinese medicine?
They are terms that describe both climatic factors and symptom patterns. Wind is associated with symptoms that appear and change quickly or that affect the upper part of the body. Dampness is associated with heaviness, swelling, tiredness and sluggishness. They should not be taken literally: a dampness pattern does not imply having been in a damp place.
Health notice. This content is educational and describes concepts of Traditional Chinese Medicine together with the available scientific evidence. It does not replace diagnosis or treatment by a healthcare professional. If symptoms are persistent or severe, consult your doctor. Safety guide.
