Herb has characters and functions. Herb's characters include properties and flavors. Herb's functions include actions of lifting, lowering floating and sinking, as well as channel tropisms.

1. Properties and flavors

Properties and flavors are also known as four properties and five flavors. Every drug has its property and flavor.

Property refers to the cold, hot, warm or cool nature of a drug. These properties of drugs are so sorted out according to the different actions of the drugs on the human body and their therapeutic effects. For example, drugs which cure heat syndrome (yang syndrome) have a cold or cool property, whereas drugs which cure cold syndrome (yin syndrome) have hot or warm property.

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 Cnatured 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 drug's actions other than tastes. Therefore, the flavors of some drug described in books on material medical 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 fro 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 effect 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 tin 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 use 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 I 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.

Drugs of the same flavor generally have similar actions, and drugs of different tastes have quite different actions. Yet some drugs are the some in property but different in flavor, or the same in flavor but different in property, and, therefore, their effects are not all the same. Both coptis root and dried rehmannia root, for instance, have the same cold property, yet coptis root is bitter in flavor while dried rehmannia root sweet. The former has the effects of clearing heat and drying dampness and is used for damp-heat syndrome, while the latter has the effects of clearing heat and nourishing yin and is used for the condition of consumption of yin due to febrile diseases. Another example is the use of ephedra and peppermint, both of which have a pungent flavor. However, the property of ephedra is warm, whereas the property of peppermint is cool. The former has the effects of dispersing wind-cold pathogens and is used to treat exterior wind-cold syndrome, while the latter has the effects of dispersing pathogenic wind-heat and is used to treat exterior wind-heat syndrome. Therefore, the property and flavor of a drug should not be treated separately but should be taken into consideration as an integrated whole. Only in this way can drugs be understood and used correctly.

2. Actions of lifting, lowering floating and sinking

Actions of lifting, lowering floating and sinking refer to the upward, downward, outward or inward directions in which drugs tend to act on the body. Lifting means going up or sending up while lowering means just the opposite. Floating means going outward or sending to the surface, whereas sinking means going inside or purging away. Lifting and floating drugs have upward and outward actions and are used for elevating yang, relieving exterior syndromes by means of diaphoresis, dispelling superficial wind and cold, inducing vomiting, causing resuscitation, etc. Lowering and sinking drugs have downward and inward actions and are used for clearing heat, purgation, promoting micturition, removing dampness, checking the exuberance of yang, sending down an adverse flow of qi to stop vomiting, relieving cough and asthma, improving digestion to remove stagnated food, tranquilizing the mind with heavy properties, etc. As the locations of diseases are different with some in the upper part of the body and some in the lower, some in the interior and some in the exterior, and as the tendencies of disease are divided into upward (as with vomiting), downward (e.g. diarrhea, metrorrhagia, metrostaxis and proctoptosis), outward (e.g.. spontaneous or night sweating) and inward (e.g. internal transmission of exterior syndrome), the lifting, lowering, floating and sinking actions of drugs are used in correspondence with the locations of diseases but in opposition to the tendencies of diseases. Generally speaking, for the diseases located in the upper part or the exterior, it is appropriate to use lifting and floating drugs instead of the lowering and sinking.

For example, for the exterior syndromes, lifting and floating drugs should be chosen. One the contrary, for the diseases located in the lower part or the interior, such as dry stool or constipation, it is proper to use lowering and sinking drugs, not the opposite. For the diseases of which the manifestations tend upward, drugs of lowering actins should be given rather than that of lifting, just as in the treatment of headache and vertigo due to hyperactivity of the liver-yang, drugs of lowering and sinking actions should be used to calm the liver and suppress hyperactivity of the liver-yang. On the contrary, for the diseases of which the manifestations tend downward, it is suitable to use lifting drugs instead of lowering drugs. For example, in the treatment of chronic diarrhea and proctoptosis due to sinking of qi of the middle-jiao, it is wise to choose lifting drugs to invigorate qi and lift yang.

The lifting, lowering, floating and sinking actions of drugs have close relationship with their properties and flavors. Most drugs which are pungent or sweet in flavor and warm or hot in property have lifting and floating actions, whereas most drugs, bitter, sour, or salty in flavor and cold or cool in property have lowering and sinking actions. The lifting, lowering, floating and sinking actions also have some relationship with the textures of drugs. Generally speaking. Most of the light substances have the actions of lifting and floating. In contrast, most of the heavy drugs have the actions of lowering and sinking. However, though some drugs are light, they have lowering and sinking actions; and conversely, some heavy drugs have lifting and floating actions. In addition, the lifting, lowering, floating and sinking actions can also be influenced or even altered through the processing and the joint use of drugs. For example, lowering and sinking drugs can have lifting and floating actions after processing with wine, while lifting and floating drugs can have lowering and sinking actions after preparation with salt solution. If lifting and floating drugs are dispensed together with a great amount of lowering and sinking drugs, they many also have lowering and sinking actions; and similarly, when lowering and sinking drugs are used together with a great amount of lifting and floating drugs, they may exhibit some lifting and floating character.

3. Channel tropism

Channel tropism refers to a drug's selective therapeutic effects on a certain part of the body. A drug may exert obvious or specific therapeutic action on the pathological changes in a certain channel (including some viscera thereof) or several channels, but with little effects on the others. For instance, among the heat-clearing drugs, some only clear the heat either in the lung channel or in the liver channel or in the heart channel, etc. Again, among the tonics, some strengthen the lung while others strengthen the spleen or the kidney.

Channel tropism is based on the theory of viscera, the theory of channels and collaterals, and is summed up according to the curing particular diseases for which a drug is effective. The human body is an organic whole in which the channels and collaterals link up with the interior and exterior and all parts of the body. A pathological change in the exterior may affect the viscera while diseases in the viscera may, in turn, find expressions in the exterior of the body. For this reason, the symptoms and signs of diseases occurring in different parts of the body can be understood systematically according to the theory of channels and collaterals. For instance, the flaring up of stomach-fire may result in swollen gum; and whenever there is stagnation of liver-qi, pain in the hypochondriac region will be present. Since the swelling and pain of the gum disappear when gypsum is administered, and hypochondriac pain relieved with the use of bupleurum root, we may infer that gypsum acts on disorders of the stomach channel and bupleurum, the liver channel. The above examples show that the theory of channel tropism is summed up through clinical practice.

The channel tropism theory should be associated with the theories of the four properties and five flavors, and actions of lifting, lowering, floating and sinking of drugs. Different drugs acting on the same channel have different effects owing to their different properties, flavors and actions of lifting, lowering, floating and sinking. For example, scutellaria root, dried ginger, lily bulb, and lepidium seed all act on the lung channel, but scutellaria root can clear lung-heat, dried ginger can warm lung-cold, lily bulb can be used to make up for lung deficiency, and lepidium seed is used to soothe excess syndrome of the lung. Therefore, only when attention is paid to the different aspects of a drug, can its actions be comprehensively analyzed and the drug correctly employed. Besides, according to the theory that viscera as well as channels and collaterals are physiologically related to one another, and pathologically affect one another, when there is pathological change in one channel, drugs acting on other channels should be used in addition to the prescription for the diseased channel itself. For in stance, for abnormalities in the lung channel, drugs for strengthening the spleen channel should be added, and in case of hyperactivity of the liver-yang, drugs for nourishing the kidney-yin should be used at the same time.

---------- Source The Chinese Materia Medica