External pathogenic factors
With External causes of disease, we look at six main elements: Wind, Cold, Heat, Damp, Dryness and Summer-Heat.
Some of these elements can combine with each other and give rise to patterns such as Wind-Cold, Wind-Heat, Damp-Cold and Damp-Heat.
Through one of the properties of Yin and Yang, that of Yin being able to transform into Yang and Yang being able to transform into Yin, what started off as one pattern can, over time, change into another pattern.
So for example, Cold can transform into Heat and Damp-Cold can transform into Damp-Heat giving rise to a new set of symptoms.
External Wind
Wind symptoms can be caused by being exposed to draughts or sudden changes in weather.
Wind is sometimes referred to as the spearhead of disease as it tries to penetrate past the Wei-Qi and in doing so can combine with other External Pathogenic Factors (EPFs) such Cold to give Wind-Cold or Heat to give Wind-Heat.
As the Wind battles against the Wei-Qi, or more technically the Zhong or Upright Qi, it can give rise to symptoms of alternating chills and fever.
Wind is sudden, changeable and erratic: it comes and goes suddenly, moves fast, changes direction and symptoms involving External Wind can behave in a similar way as they migrate around the body or come and go quickly.
As this rapid movement or change is a typical Wind symptom so arthritic-type pains that migrate from joint to joint, or eczema that moves around the body would be said to have a Wind component involved.
Illnesses of sudden onset such as a stiff neck or shoulders, infectious disease such as the common cold or sudden skin diseases tend to involve External Wind.
External Cold
Externally, Cold attacks the most exposed parts of the body first such as the hands, face, feet, lower back and any sites of an old injury.
An invasion of External Cold leaves a person feeling chilly and with an aversion to cold so they feel better with warmth and may want to avoid a cold weather or a cold environment.
External Cold causes contraction, much like water as it freezes so that when the channels are affected, the pain may be described as a ‘biting pain’ or when the muscles and tendons are affected, this can lead to stiffness, tightness and rigidity, ‘frozen shoulder’.
External Cold damages Yang and typically affects the Uterus, Liver, Stomach, Spleen and Large Intestine.
As the Yang is damaged by External Cold, it causes things to slow down and stagnate and can cause Qi and Blood to stagnate and for the pulse to become deep and slow.
Cold also causes excretions and discharges, such as phlegm, urine, vomit and diarrhoea to become clear, transparent or white, copious or watery.
The tongue develops a thick, white coat to reflect the External Cold and indicate that it is Excess condition.
Clinical manifestations of cold for Cold in the Exterior of the body (i.e. at the Channel or Muscle level), symptoms can include:
- Stabbing, biting pain.
- Fluid accumulation such oedema.
- An aversion to cold.
- Clear watery discharges.
- Whole body aches.
Once External Cold affects the Interior of the body, symptoms depend on the Zang-Fu affected. For example:
- With External Cold Invading the Stomach this can give rise to abdominal pain and vomiting of clear liquid.
- External Cold affecting the Spleen can cause loose stools and abdominal bloating.
- External Cold Invading the Uterus can cause deep period pains that are better for heat, create a longer delayed menstrual cycle, and also cause fertility issues.
External Heat
External Heat is one step on from External dryness (with Fire being the next step on from Heat).
External Heat can be caused by constant exposure to a hot environment or as a progression on from Dryness.
It can also be caused by the transformation of External Cold (which is Yin) into Heat (which is Yang) based on one of the properties of Yin and Yang, namely that Yin can transform into Yang (and vice versa).
Heat dries things out and speed things up, leading to symptoms such as:
- Tongue – dry red body, yellow coat.
- Pulse – rapid.
- Constant thirst.
- Constipation.
- Physical stiffness and rigidity as the body fluids and Blood become drier and thicker.
- Scanty urine (which could be dark).
- Heat also disturbs the Shen causing restlessness and agitation.
- Heat flares upwards and can manifest in the upper part of the body (e.g. red face or acne and rosacea).
- Heat accumulates in local areas causing inflammation which feels hot to the touch.
- Heat warms things up and causes them to become ‘reckless’ for example sudden gushing nosebleeds due to the Blood becoming hot and reckless.
If the Heat is at the Exterior of the body at the channel or muscle level it may manifest with symptoms such as: fever, burning pain, joints and inflammations that feel hot and look red.
If the Heat is in the Interior of the body it can cause symptoms such as: Fever, feeling hot, an aversion to heat. discharges that are thick, sticky and yellow such as thick sticky Phlegm or yellow urine (which may also have a burning sensation).
External Damp
External Damp is sometimes felt as being ‘wrapped up in a wet blanket’ and is typically the result of living or working in a damp environment or wearing damp or wet clothing.
External Damp is slow, heavy, stubborn and lingering and therefore Damp conditions tend to last a long time before they start to resolve.
Damp also causes stagnation in the channels leading to local swelling, oozing (as in weeping eczema), stiffness and heaviness where limbs feel heavy and a person might feel ‘bogged down’.
Damp can also combine with other EPF’s such as External Cold leading to Damp-Cold causing cramping pain with local swelling or with Heat leading to Damp-Heat causing burning pain with local swelling.
If the External Damp is in the Exterior of the body at the channel or muscle level typical symptoms may be:
- Stiff, swollen, achy joints.
- Worse in damp weather.
If the External Damp has reached the Interior of the body at the Zang-Fu level, it typically affects the Spleen’s function of transformation and transportation of body fluids leading to symptoms such as physical fatigue, a feeling of heaviness, oedema (especially around the abdomen) and loose stools.
External Dryness
External dryness from prolonged exposure to heat (such as working in a hot environment or from hot weather) consumes fluids and can lead to symptoms of dry skin and thirst.
As warm or hot air is breathed in, this can cause dryness of the Lungs giving rise to symptoms such as a dry cough, dry nose and dry throat.
Summer-Heat
Summer Heat is caused by being in a very hot environment, typically from the Sun as in sun-stroke.
Summer-Heat damages Qi and Yin and can give rise to symptoms such as a high fever, thirst, rapid breathing and a disturbed Shen where the person might become delusional.
