Causes of disease in Chinese medicine

Classical Chinese medicine identifies three broad categories of disease aetiology: External Pathogenic Factors (the “Six Evils”), Internal causes (the Seven Emotions), and Miscellaneous causes (diet, lifestyle, trauma, parasites). These are not metaphors but descriptive categories derived from systematic clinical observation, and they map cleanly onto modern understandings of infection, immune dysregulation, the autonomic stress response and lifestyle-related disease.

The six external pathogenic factors

These describe environmental influences that, in susceptible people, can invade the body and cause disease. Each “Evil” has characteristic clinical features:

1. Wind (Feng)

The “ringleader of the hundred diseases”. Characteristically rapid onset, affects the upper and surface body, moves and changes (symptoms that come and go, migrate or appear suddenly). Combines easily with the other Evils — Wind-Cold, Wind-Heat, Wind-Damp. Internal Liver Wind produces tremor, twitches, dizziness and stroke-like presentations.

2. Cold (Han)

Contracts and slows. Produces aversion to cold, pale complexion, clear copious discharges, sharp localised pain that is improved by warmth, watery diarrhoea. Damages the Yang — chronic Cold exposure depletes Spleen and Kidney Yang.

3. Heat / Fire (Re / Huo)

Ascends and inflames. Produces fever, red face, thirst, dark urine, hard dry stool, restlessness, bleeding (Heat “forcing” Blood out of vessels), skin rashes. Damages Yin and Body Fluids — prolonged Heat leads to Yin deficiency.

4. Dampness (Shi)

Heavy, sticky, lingering. Produces heaviness of head and limbs, oedema, sticky mouth, lassitude, loose stools, vaginal discharge, sticky tongue coat. Damp readily combines with Heat (Damp-Heat) or Cold (Cold-Damp). The Spleen is most susceptible to Damp; conversely, Spleen Qi deficiency generates internal Dampness.

5. Dryness (Zao)

Damages Body Fluids. Produces dry skin, dry mouth, dry throat, dry stool, scanty urine, dry cough with little sputum. Characteristic of autumn weather and of central-heated dry indoor environments. The Lung is most susceptible.

6. Summer Heat (Shu)

A specifically seasonal Heat that combines with Dampness (humid summer) or pure intensity (heatstroke). Produces sudden high fever, profuse sweating, exhaustion, thirst. Damages both Qi and Body Fluids quickly.

The seven emotions (Qi Qing)

Excessive, sustained or repressed emotion damages the corresponding organ. Each emotion has a specific organ link:

1. Anger — damages the Liver; causes Qi to rise; produces irritability, headaches, hypertension
2. Joy (excessive) — damages the Heart; scatters Qi; mania, restlessness, insomnia
3. Worry / Overthinking — damages the Spleen; knots Qi; appetite loss, digestive dysfunction, fatigue
4. Grief / Sadness — damages the Lung; depletes Qi; weakness, depression, shallow breath
5. Fear — damages the Kidney; causes Qi to descend; urinary incontinence, weak knees, premature ageing
6. Fright (sudden shock) — damages Heart and Kidney; scatters Qi; palpitations, anxiety, insomnia
7. Pensiveness — damages Spleen and Heart; obsessive rumination, brain fog, sleep disturbance

This framework is highly clinically useful: chronic stress, anxiety, depression, PTSD and burnout all map onto specific organ patterns of emotional injury.

Miscellaneous causes

1. Improper diet — excess raw and cold foods damage Spleen Yang; excess rich, oily, sweet foods generate Damp-Phlegm; excess spicy/alcoholic foods generate Heat. Irregular meal timing damages Spleen-Stomach.
2. Overwork (physical, mental, sexual) — depletes Qi, Blood, Yin or Essence depending on type. Mental overwork weakens Spleen; physical overwork weakens Spleen Qi; sexual excess depletes Kidney Jing.
3. Inadequate rest and sleep — depletes Yin, particularly Liver and Kidney Yin; the 11pm–3am window is the Liver/Gallbladder time and key to constitutional recovery.
4. Trauma and surgery — cause local Blood stasis; deep trauma can produce lasting Heart and Kidney disturbance (modern PTSD picture)
5. Parasites and pestilential factors — the classical category that anticipates infection medicine
6. Iatrogenic causes — medication side effects, surgical sequelae, treatment-induced patterns (e.g., chemotherapy-induced Qi-Blood deficiency)

Why this framework still matters

The Six Evils plus Seven Emotions plus Miscellaneous causes provides a complete causal vocabulary for almost any presentation. In modern practice, “Wind-Cold invasion” describes a viral upper respiratory infection in a person whose Wei Qi is too weak to expel it; “Liver Qi stagnation” describes the autonomic and somatic pattern of chronic unprocessed stress; “Damp-Heat in the Lower Burner” describes the pelvic-floor presentation of chronic urinary or pelvic inflammation. The categories are old; the clinical picture is recognisably modern.