Looking at the tongue is a reliable and simple technique that provides a clear reflection of the patient’s inner health – particularly of the Blood and Digestion.
Practiced in China for over 3000 years, it has slowly evolved into its current form and is used by all TCM practitioners. As far back as the Ming dynasty, a book describes 135 tongue types – and they’re just from Cold induced disorders!
A systematic analysis of the tongue includes four major factors: body colour, body shape, tongue coating and tongue moisture. Each reflects a certain aspect of physiology.
Body colour — Blood, Nutritive Qi, Yin Organs
Body shape — Blood, Nutritive Qi
Tongue coating — Yang Organs
Tongue moisture — Body Fluids
The four aspects should be considered together, as one sign may take on a different significance when combined with various other signs.
Sunlight is, by far, the best lighting for viewing the tongue. Ask the patient to stick their tongue out, and ensure that you can see the whole tongue. If too much effort is used the tongue will stretch and redden, so ask them to relax a bit. The tongue will redden and darken the longer it is held out, so 10-15 second bursts are the best, asking the patient to rest for a few seconds and extend it again. It may take several views to gather all the information you need. Sometime must be given after eating or drinking. Coffee and cigarettes will turn the coat yellow.
The colour of a normal, healthy tongue is pale red. The tongue is the off-shoot of the Heart and Heart Blood flows into it, pushed by free flowing Yang Qi. The Stomach sends body fluids upward which dilute the colour slightly, producing the pale red, and also makes it moist. Other colours represent various pathologies.
Dry & thin? — Blood def
Wet & swollen? — Yang def
Always heat, the redder the hotter
With coat? — Full Heat
No coat? — Yin def
All colours may be specific to one area: Lv, Ht, Sp, etc.
The tongue body’s shape is influenced by fluids held within it. Unusual movement or position is also considered here.
Red & no coat
Reflects dampness held in the tongue
Yang def Damp
Damp - Spleen def
Heat, or Yin def
The coat reflects the functioning of the Yang Organs, particularly the Stomach. A thin, white coat is normal.
Generally, a thick coating reflects Dampness and a thin coating Deficiency, with no coat at all representing a Yin deficiency.
Grass growing on a lawn is a good analogy when learning coat diagnosis.
- You can see the body beneath it, it ‘grows’ from the tongue like grass from the It cannot be scraped off.
- It is too thick if no ground can be seen beneath
- It is too thin if it is not present, or there are bare patches in the
No coating & Red
No coating & Pale
Tongue coatings follow the same map as other features.
Independent of the coating a tongue body may be too wet or too dry. A wet tongue may even have saliva running of it and represents an accumulation of fluids from Yang deficiency, while a dry tongue body will eventually crack.
Tongue cracks usually indicate yin deficiency although long-term emotional issues can lead to a long crack down the midline extending to the Heart area due to heat from the Heart.
Mouth ulcers usually denote some form of Heat, and primarily in the Heart, Stomach or Large Intestine.