Four Natures of Chinese Herbs
The four natures of Chinese herbs or Si Qi refer to the property or nature of medicinal herbs. They are cold, hot, warm and cool.
Medicinal herbs that are cold-cool belong to Yin. In Chinese medicine, herbs with a cold-cool nature can clear Heat, purge Fire and eliminate toxic materials, and they are mainly used for Heat-syndromes.
Medicinal herbs that are warm-hot belong to Yang. These herbs have the actions of expelling Cold and restoring Yang. Thus they are mainly used for Cold-syndromes.
There are some herbs in Chinese materia medica which are known as neutral, whose proerty is neither hot nor cold and whose action is relatively mild. However, they still have some action to cool or warm, so are placed in range of the four natures of Chinese herbs.
They are determined mainly from the body’s response after the herbs are taken, which is directly related to the nature of the disease or syndrome being treated. For example, after Huang Lian (Rhizoma Coptidis) and Shi Gao (Gypsum Fibrosum) are taken, the manifestations of heat-syndrome such as high fever, thirst and profuse sweating can be eliminated. This indicates that both Huang Lian and Shi Gao are cold in nature.
Conversely, after Fu Zi (Radix Aconiti Lateralis Preparata) and Gan Jiang (Rhizoma Zingiberis) are taken, the manifestations of cold-syndromes such as aversion to cold, cold limbs, cold and pain in the stomach and diarrhoea can be relieved. This indicates that Fu Zi and Gan Jiang are hot in nature.
On the basis of syndrome differentiation, a practitioner must distinguish the hot or cold nature of disease and have a sound understanding of the hot and cold properties of Chinese medicinal herbs. This is essential to obtain the desired results from treatment and to avoid harmful results.