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Differentiation of Disease According to the Eight Principles

This is the diagnostic system of Chinese traditional medicine.

Diseases are either exterior or interior. If a pathogen such as cold invades the body then it may be superficial or exterior in its damaging effect, such as the common cold, or it may be deep or interior, such as septicaemia. Usually diseases of the exterior show mild fever, headache, generalized aches and pains, and a superficial pulse. Diseases of the interior are characterized by a high fever, thirst, restlessness, delirium, vomiting, diarrhea, a purplish-red tongue proper, with a white or yellow coating and a deep pulse.

Disease may be hot or cold. This means they may be due to the pathogen factors cold or heat. Diseases of heat show the signs of an acute infection or intestinal obstruction, whereas diseases of cold are more chronic in nature. Diseases of cold are characterized by a dislike of cold, pallor, loose stool, polyuria, a large flabby white tongue with a white coating, and a slow or deep and thready pulse. Diseases of heat show fever, dislike of heat, thirst, a red face, constipation, red scanty urine, and a red tongue proper with a yellow coating, associated with a rapid pulse.

Diseases may be xu or shi: Diseases of xu are usually more chronic in nature and are due to a deficiency of either the yin or the yang within the body. The patient is in low spirits, pale, emaciated, has palpitations and the tongue proper is light or red with a white or yellow coating, and there is a xu pulse. A shi disease is often more acute and is due to an excess of the yin or the yang within the body. This presents with irritability, distension and fullness of the chest and abdomen, scanty urine and dysuria, a red or white tongue proper with a yellow or white coating, and a shi or forceful pulse. There is a great deal of reference to xu and shi and it is important to realize that xu really means a deficiency, and shi really means an excess.

The last two principles are yin and yang. They are the generalization of the above ideas, which have already been discussed in Part I of this section.

Characters and Functions of Herbal Drugs

Each drug has its own specific characters. In traditional Chinese medicine, the different characters of drugs are employed to treat diseases, rectify the hyperactivity or hypoactivity of yin or yang, and help the body restore its normal physiological functions, consequently curing the diseases and restoring health. The characters and functions of these drugs concerning medical treatment include drugs' properties and flavors.

Drugs of cold and cool natures and drugs of warm and hot natures are of opposite properties. A cold-natured drug is different from a cool-natured one only in degree, and so is a warm-natured drug from a hot-natured drug. Most of the cool- or cold -natured drugs have the effects of clearing heat purging fire, removing toxic substances, and nourishing yin, and are used to cure heat syndromes. On the contrary, drugs of warm or hot nature usually have the effects of dispersing cold, warming up the interior, supporting yang, and treating collapse, and are therefore used to treat cold syndromes. In addition to the four properties mentioned above, there is the fifth, the neutral or mild one. When a drug is neither hot nor cold in nature, it is said to be neutral. It can be used for either hot or cold syndromes. Yet, drugs of neutral nature usually tend to be either slightly hot or slightly cold. That is why drugs are generally said to be of four properties only.

"Flavors" refers to the tastes of drugs, i. e. pungent, sweet, sour, bitter, salty, tasteless and astringent. Since sweet and tasteless usually coexist, and since sour and astringent drugs have the same effects, pungent, sweet, sour, bitter and salty tastes are the cardinal flavors and are habitually known as five flavors. Drugs of different flavors and different compositions show different pharmacological and therapeutic actions, while drugs of the same taste usually have similarities in effect and even in composition. The flavors don't necessarily refer to the real tastes of the drugs. Sometimes they are sorted out according to drugs' actions other than tastes. Therefore, the flavors of some drugs described in books on materia medica are often different from their true tastes. Various flavors have different effects. They are explained separately as follows:

Pungent flavor: Drugs that are pungent in flavor have the effects of dispersing exopathogens from superficies of the body and promoting the circulation of the vital energy and blood. Pungent drugs are usually used for the treatment of superficial and mild illnesses due to affection by exopathogens, stagnation of vital energy, blood stasis, etc.

Sweet flavor: Drugs of sweet flavor have the effects of nourishing, replenishing, tonifying, or enriching the different parts or organs of the body, normalizing the function of the stomach and spleen, harmonizing the properties of different drugs, relieving spasm and pain, etc. Drugs of sweet flavor are usually effective in treating syndromes of deficiency type, dry cough, constipation due to dry intestine, incoordination between the spleen and the stomach, various pains, etc. Besides, some of the sweet drugs have the effects of detoxication.

Sour flavor: Drugs of sour flavor have the effects of inducing astringency and arresting discharge. Sour drugs are often used to treat sweating due to debility, chronic cough, chronic diarrhea, emission, spermatorrhea, enuresis, frequent micturition, chronic leukorrhagia, metrorrhagia or metrostaxis, etc.

Bitter flavor: Drugs of bitter flavor have the effects of clearing heat, purging fire, sending down the adverse flow of qi to treat cough and vomiting, relaxing the bowels, eliminating dampness, etc. Such drugs are mostly used for syndromes of pathogenic fire, cough with dyspnea, vomiting, constipation due to heat of excess type, damp-heat syndrome, or cold-damp syndrome and other syndromes.

Salty flavor: Drugs of this taste have the effects of relieving constipation by purgation, and softening and resolving hard mass. Salty drugs are mostly used in treating dry stool and constipation, scrofula, goiter, mass in the abdomen, and other problems.

Tasteless flavor: Drugs of this flavor have the effects of excreting dampness and inducing diuresis, and are commonly used for edema, dysuria and others.

Astringent flavor: Drugs of this flavor have similar actions as those of sour flavor.