1. Visual ~ including body type, face, and tongue
2. Palpation ~ including pulse, abdomen (hara), and pressure points
3. Inquiry ~ including questions about health history, diet, medications, sleep, symptoms... et cetera.
4. Listening & Smelling ~ including quality of voice and body odors.
Our main references for tongue assessment include: Giovanni Maciocia's Tongue Diagnosis in Chinese Medicine and Barbara Kirschbaum's Atlas of Chinese Tongue Diagnosis. Maciocia's The Foundations of Chinese Medicine and Diagnosis in Chinese Medicine also cover tongue assessment, as does Nigel Wiseman's & Andrew Ellis' Fundamentals of Chinese Medicine.
Like other forms of diagnosis, tongue assessment offers both a general way to gather information as well as a potential source of specific information. To begin one must first observe tongues, which are usually hiding in mouths out of sight. So in one way or another you have to ask to see a person's tongue. Generally, people are shy about showing their tongues. Perhaps after you explain that you are studying herbal medicine you will find some agreeable individuals.
First, take note of the tongue body. Is it thick or thin? Is it pale or red? Again, the various traits we are looking for are learned through observation and comparison. You should also observe the tongue moss, or coating, taking note of whether it is thick or thin, colored or pale, or missing from all or part of the tongue.
A healthy tongue is pink. Look for abnormal colors like red, purple, and blue; and for paleness. The tongue should not be too thin or swollen to the degree that pushes on the teeth creating a scalloped edge. A healthy tongue is free of cracking, so if cracks are observed take note of their quality and position. A healthy tongue is coated with a layer known as the tongue's moss. If the moss is missing, colored, or thick, it is abnormal.
To begin, simply look at tongues. If you are in a position, such as a health care job, you may know or be able to gather information about an individual's health. But to begin learning you only need to practice observation and to gain discernment through exposure to different tongues. Pink and red are on a scale. If you only observe one or a few tongues you will likely not understand pink verses red. Over time, seeing many different tongues, you will eventually understand at a glance when you are looking at a tongue that is more red than usual.
We have already covered the basics of tongue diagnosis: Red indicates heat. Pale indicates deficiency (which is associated with coldness). Thick moss indicates dampness. A lack of moss indicates dryness. So, we can observe the four qualities of hot, cold, damp, and dry in the tongue.
Combinations of these signs have special meaning too: If the moss is thick and yellow, damp-heat is indicated. If the moss is missing and the tongue is very red, then dryness due to heat is indicated or heat due to dryness. And so on. As we discuss details of tongue diagnosis in class, I will add them to this post.
We also already introduced the concept of the tongue positions being associated with different organs; namely, the five main organs: the heart, lungs, liver, kidneys, and spleen.
To bring this around to herbs, we can start with some basic, generalized concepts:
If the tongue appears red, indicating heat, we can consider heat-clearing herbs (see materia medica) such as Dandelion, Barberry, or Burdock. However, if the moss is missing, indicating either that the heat is due to yin deficiency (dryness) or that the heat has damaged the yin (fluids), we need to use moistening herbs like Marshmallow either instead or with those listed. Dandelion and other bitter herbs have a drying nature. Barberry is especially drying. So, even though they are heat-clearing, they are contraindicated if the moss is missing.
If the tongue appears pale, indicating deficiency of blood, then we want to use blood tonic herbs. Local herbs include Nettles, Yellow Dock, and the dark berries like Blueberry and Blackberry. Chinese herbs include prepared Rehmannia, He Shou Wu, and Dong Quai. Since our local "blood building" herbs have decidedly cleansing qualities, this is one group of medicininals where Chinese herbs stand out. In the examples listed, the blood nourishing properties are enhanced through preparation (see this description for Rehmannia.)
If the tongue moss is missing, indicating dryness, we want to moisten the body with yin tonics like Solomon's Seal and Marshmallow. If pale and without moss (dry and cold), a warming and moistening herb like Licorice is indicated.
If the moss is excessive, indicating dampness, we can utilize herbs that remove dampness. If the moss is white, indicating damp-cold, than warming herbs like Elecampane are indicated. If the moss is yellow and thick, damp-heat is indicated and the bitter herbs mentioned above (Dandelion & Barberry) are appropriate.