Traditional Chinese Medicine, or TCM, is one theory of deciding how to treat a patient. In TCM, there are 8 principles. These 8 principles are four sets of opposites that helps an acupuncturist to decide how to treat a patient.
The 8 principles ask whether the disease is internal or external. For instance, an internal disease is typically something that has been going on for awhile and is chronic. Disease, in Asian medicine tends to move inwards. An exterior problem is something like a cold or an acute trauma, where the problem has come on quickly and suddenly.
After deciding if the disease is interior or exterior, the acupuncturist must decide if the disease is hot or cold. For instance, in evaluating a cold, the acupuncturist will ask what the symptoms are. A person with fever or with a cold that has a sore throat, will typically be classified as having a hot disease. Cold disease in the common cold would manifest in more chills than fever and more of an achy body.
The next set of opposites is whether the disease is excess or deficient. Deficient diseases are because there is not enough qi, yin, yang or blood. In this case the problem needs to be remedied by building up that aspect that is lacking. If a disease is excess it can mean that qi or yang or yin is in excess but it will probably mean that there is an external influence causing the excess. A cold can often be an excess condition as something has invaded the body and there is excess of it’s influence.
Finally, the practitioner must decide if the condition is a yin condition or a yang condition. This part comes last as each of the other pairings has a yang aspect or a yin aspect. If there are more yin aspects to the disease, then it is a yin disease. If there are more yang aspects, then it is a yang disease. Notice that there are three of each before the diagnosis comes to yin or yang, so a tie is impossible.
This method is the method predominantly taught in acupuncture schools in the United States. This is a very simplified formula. It is also not the only theory. The other main theory that is taught in the United States is called the Five Element theory.