(34) Chinese Herbal Medicine
Introduction to Chinese Herbal Medicine
Traditional Chinese Medicine: In Depth
What are the differences between Chi Shao Yao (Paeoniae radix rubra) and Bai Shao Yao (Paeoniae radix lactiflora)?
Chi Shao Yao and Bai Shao Yao come from similar plants. Both are cold in nature and enter the Blood and the Liver meridian. Because Chi Shao Yao is cold and bitter, it is able to reduce Liver-Heat as well as Heat in the Blood. It has a dispersing property, can invigorate the Blood and remove congealed Blood, and is therefore often used for treating pain due to Blood stagnation.
Compared with Chi Shao Yao, Bai Shao Yao is less cold but bitter, so it can clear Liver-Heat or Heat in the Blood, but its function is weaker than that of Chi Shao Yao. One difference is its sour taste, which results in an astringent property. Cold and sourness may generate and stabilize the Yin. As it enters the Liver meridian, it particularly nourishes the Liver-Yin and Blood. It is an appropriate herb when there is Yin deficiency with slight Empty-Heat in the Blood. In this situation, the main symptoms are dizziness, dry and burning eyes, irritability, hypochondriac pain and distension. Like Chi Shao Yao, Bai Shao Yao can also alleviate pain, but it alleviates pain caused by Liver-Yin and Blood deficiency, in which the muscles and tendons lose their nourishment. This pain is cramping in nature, such as in abdominal pain and cramp after diarrhea, menstruation, labor or cramp of the muscles of the limbs. Moreover, as Bai Shao Yao has a sour taste, it may stabilize the Yin and Body Fluids and inhibit sweating, so is used for spontaneous sweating and night sweating.
What are the differences between and characteristics of Sheng Di Huang (Rehmanniae radix) and Xuan Shen (Scrophulariae radix) in the function of clearing Heat?
Sheng Di Huang and Xuan Shen are both cold in nature. They have similar functions in clearing Heat, especially when the Heat has consumed the Yin of the body. Both of them are often used for treating internal Heat syndromes with Yin deficiency.
However, there are differences between their functions. Sheng Di Huang is sweet, bitter and cold and moist in nature. It enters the Heart, Liver and Kidney meridians. Bitterness and Cold can clear Heat, and sweetness and Cold may generate the Yin of the body. It can directly clear Excessive-Heat in the Heart and Liver and therefore calm the Mind, and relieve irritability, restlessness, thirst and sensations of warmth in the chest. It is often used in febrile diseases. Sheng Di Huang can also be used for Empty-Heat due to deficiency of Heart-Yin, Liver-Yin or Kidney-Yin. The manifestations are insomnia, restlessness, irritability, a dry throat and ‘bone-steaming’ disorder.
As this herb enters the Heart and Liver meridians, it can also enter the Blood. It is particularly effective in clearing Heat from the Blood, cooling the Blood and stopping bleeding. This is why Sheng Di Huang is an important herb for clearing Heat not only in the Qi level, but also in the Nutritive and Blood levels. It can generate the Yin to prevent the consumption of Yin from Heat. Xuan Shen is bitter, cold and salty, and enters the Kidney meridian. It can clear Heat and reduce Fire. Unlike Sheng Di Huang, it is not sweet and has no function in generating the Yin. As it does not enter the Liver and Heart meridians, it does not enter the Blood and has no function in cooling it. In clinical practice, Xuan Shen is often used instead of Sheng Di Huang to treat Excessive-Heat and Empty-Heat in the Heart, and to relieve thirst, a dry throat, sensation of warmth in the chest and irritability. This is because it has a characteristic of lifting the Kidney Water (Yin) upwards to reduce the Fire of the Heart. It is often used for Excessive-Heat and Empty-Heat in the Upper Jiao. However, its function is not to nourish the Yin but to transport it so it is quite different from Sheng Di Huang.
When a patient has Yin deficiency, especially Kidney-Yin deficiency, this herb should not be used over a long period of time, or it should only be used with herbs that tonify the Yin. Xuan Shen also has some other characteristics. It is salty and able to soften hardness and is especially effective in relieving toxin. It is used for painful and swollen throat or eyes, chronic dry eczema, sores, scrofula and tumors.
However, Xuan Shen can have a toxic effect if it is used in overdose; 10-15 grams of crude herbs or 1–1.5 grams of concentrated herbal powder per day is a safe dosage.
What are the differences between the products of Di Huang (Rehmanniae radix)?
There are three kinds of product from the same plant. The part of the plant that is used is called Di Huang. As it is processed in different ways, the functions are different and the names are also different.
The first is Gan Di Huang, which is also called Sheng Di Huang. (‘Gan’ means ‘dry’ and ‘Sheng’ means ‘raw’.) It is the most commonly used form of Di Huang. The herb is processed by baking, and is then dried by wind or the sun until it turns black. Gan Di Huang is sweet, bitter and cold, and enters the Heart, Liver and Kidney meridians. Sweetness and Cold may generate the Yin and Body Fluids; as this herb is also moist in nature, it can nourish the Yin of the body. Bitterness and Cold can clear Heat, cool the Blood and stop bleeding. This herb is especially effective when internal Heat has injured the Yin and disturbed the Blood. For instance, this may occur in febrile disease with symptoms of fever, thirst, irritability, constipation, scanty urine, night sweating, flushes, menorrhagia, nose bleeding and hemoptysis.
Xian Di Huang is fresh Di Huang. It is collected in spring or autumn and is used directly after washing. It is juicy and fresh, sweet, bitter and very cold. The function is similar to the dried form but weaker in its effect of nourishing the Yin and stronger in clearing Heat. It is very effective in relieving irritability and thirst. This herb is used in clinical practice for diabetes. When Sheng Di Huang is steamed, or alternatively, soaked in rice wine and dried in the sun until both its outside and inside have turned black and glossy, the product is called Shu Di Huang (Rehmanniae radix praeparata). Shu Di Huang is quite different from Sheng Di Huang. The main difference is that it is not cold but warm in nature and sweeter in taste. Sweetness and warmth can generate the Qi; sweetness and glossiness can tonify the Essence and Blood. As it enters the Kidney and Liver meridians, its main function is to tonify the Kidney-Essence and the Liver-Blood. It is a strong herb for treating dizziness, tinnitus, forgetfulness, weakness in the back and knees, and tiredness due to deficiency of the Kidney-Yin and Essence, Liver-Yin and Blood. Shu Di Huang is able to reduce Empty-Heat but its action is quite different from that of Gan Di Huang and Xian Di Huang. It is used in conditions where the Blood and the Kidney-Essence have been severely consumed and they are not able to control the Fire so the Empty-Fire blazes up. The symptoms are ‘bone steaming’, warmth in the palms and soles, fever in the afternoon or in the evening, hot flushes and night sweating. In addition, as it is not cold, it does not have the function of clearing Heat and cooling the Blood as with Sheng Di Huang and Xian Di Huang.
What are the characteristics of pathological change when Heat enters the Blood and what precautions should be observed when using herbs that cool the Blood and stop bleeding?
Herbs that cool the Blood are used for conditions where Heat enters the Blood. Heat in the Blood causes several specific pathological changes. First of all, Heat disturbs the Blood circulation so that the Blood moves recklessly and leaves its normal pathways; specific symptoms of this include bleeding, such as nose bleeding, hemoptysis, uterine bleeding, and blood in the urine and stools. Meanwhile, Heat may consume the Blood, making the Blood thicker and forming congealed Blood. When the Blood is disturbed by Heat it may also directly cause stagnation. In this situation, deep-red maculopapular or other types of rashes appear in infectious diseases such as scarlet fever, epidemic meningitis and encephalitis, as well as in skin diseases such as eczema. If Heat enters the Blood, then the patient does not feel thirsty or rinses the mouth with water but has no desire to swallow it, although the tongue proper is red and the pulse is rapid. This indicates that the Heat is consuming the Blood instead of the Body Fluids.
In treating the syndrome of Heat in the Blood, an important principle is to cool the Blood and avoid Blood stasis. The Blood in a normal condition should circulate smoothly and quietly. Heat may force it to move faster, become unstable and, at the same time, the Heat may consume the Blood and cause Blood stagnation and bleeding. If cold herbs are used they may slow the Blood circulation but may also cause the Blood to stagnate. Therefore, to treat Heat in the Blood, herbs that enter the Blood and are coldpungent-sweet or sour-cold in property are often used-for example, Sheng Di Huang (Rehmanniae radix), Chi Shao Yao (Paeoniae radix rubra), Um Dan Pi (Moutan cortex) and Zi Cao (Arnebiae/ Lithospermi radix). They have the function not only of cooling the Blood but also of promoting its circulation and preventing its stagnation. Some are pungent, which may disperse stasis; some are sweet, which may generate the Yin. They mainly enter the Heart and Liver meridians so that they can easily regulate the Blood circulation. These herbs are suitable for the pathogenic changes of Heat in the Blood.
To treat Heat in the Blood, cold and bitter herbs should not be used as they may dry the Blood. Herbs that enter the Qi level should not be used either because the pathological change is not in the Qi level. Very cold herbs should not be used for a long period of time or in a very large dosage, otherwise they may cause Blood stasis.
