Earth of Metal: Shao Yao 芍藥

味酸皆屬金，五味[子]為之主，枳實為木，豉為火，芍藥為土，薯蕷為水。

All sour belongs to metal, for it is governed by Wuweizi; Zhishi is wood, [Dan Dou] Chi is fire, Shaoyao is earth, and Shuyu [Shanyao] is water.

Shaoyao is peony root (Radix Paeoniae), but in modern Chinese Herbalism there is no generic peony root as such – we differentiate between Baishao (白芍) or White Peony (Radix Paeoniae Alba) and Chishao (赤芍) or Red Peony (Radix Paeoniae Rubra). Both herbs in modern TCM theory are said to effect the Blood, with Baishao having a more nourishing quality and Chishao are more moving and cooling quality, respectively.

Classical Chinese herbal texts, including the Tang Ye Jing, Shen Nong Ben Cao Jing, and the Shang Han Lun, do not differentiate between Baishao and Chishao - they just refer to “Shaoyao”. There is often debate over whether a given formula should use Baishao or Chishao. Generally most contemporary practitioners use Chi Shao if there is more excess – such as Blood Stasis or swelling - and Bai Shao if there is more deficiency.

With that in mind, let’s begin by looking at the Shen Nong Ben Cao Jing’s entry for Shaoyao:

芍藥 味苦、平。主邪氣腹痛，除血痹，破堅積、寒熱、疝瘕，止痛，利小便， 益氣。生川谷。

Shaoyao: Its flavor is bitter and [its temperature is] neutral. It governs pernicious qi [causing] abdominal pain, removing blood impediment, breaking hard accumulations, cold and heat, moundings and masses, stops pain, smooths urination, and boosts qi. It grows in rivers and valleys.

The phrase "pernicious qi abdominal pain” (邪氣腹痛) is the key for understanding how these different accounts of Shaoyao come together to describe the actions and indications of this herb. Abdominal pain is probably the most clinically useful sign for applying Shaoyao.

Herbalists who are trained in various Japanese lineages of abdominal diagnosis typically look for specific signs of a tight or spasming rectus abdominus, for example. And while there are much broader applications for Shaoyao, we consistently find a close association between Shaoyao and abdominal symptoms. Exploring this relationship will help us to understand how Shaoyao is used in classical Chinese herbalism, as well as what it means to say that Shaoyao is the Earth of Metal. Shaoyao’s action can be understood as bringing the activity of Metal into the realm of Earth.

Bai Shao Yao, c/o sea of chi

This is easy enough to relate to the condition of abdominal pain, since the abdomen belongs to the Earth, as it lies in the center and house the Spleen and Stomach, the Earth organs. Shaoyao acts to bring Metal into this dynamic, by gathering (the action ascribed to the Sour Flavor of Metal); specifically, by gathering nutritive fluid (which, insofar as it originates in the Middle Jiao, can be ascribed to Earth).

Gathering nutritive fluid provides the material substrate for Blood formation, which accounts for the Blood nourishing action ascribed to Shaoyao (and Baishao in particular). Shaoyao’s gathering action moistens, nourishes, and softens. Moreover, it is this ability to gather the nutritive fluids that also provides a counterbalance to the moving, circulating action of Guizhi, creating the most distinctive and versatile duiyao pairings in the work of Zhang Zhongjing, the Wood of Wood with the Earth of Metal.

One of the first things we learn about as practitioners is the ubiquity of the pattern of excessive Wood invading the Earth. Indeed, the opening passage of the Jin Gui Yao Lue uses the relationship of Wood and Earth as an example to discuss how disease is transmitted:

夫治未病者，见肝之病，知肝传脾

One who treats disease when it has not manifested sees the Liver is diseased, and knows it will pass from the Liver to the Spleen [and that] one must first fill the Spleen…

As a Metal herb, Shaoyao can drain excessive Wood, however it accomplishes this by gathering Yin fluid, which has a moistening, soothing effect.

This treatment strategy is especially effective in protecting the Earth against the activity of excessive Wood. In the article on Zhishi, we discuss Zhishi Shaoyao San, a two herb combination indicated in the case of abdominal fullness with vexing pain (腹痛煩滿). Our understanding of this formula is deepened and completed when we consider the combination of Zhishi, the Wood of Metal, and Shaoyao, the Earth of Metal, with Zhishi more forcefully bringing a descending mandate while Shaoyao gathers, nourishes and softens.

Line 30 of the Shang Han Lun discusses the use of Shaoyao Gancao Tang. It states that when there is “...continued slight urgency and spasm of the lower legs, one should give a heavy dose of Shaoyao Gancao Tang and then the lower legs will be able to stretch.” (脛尚微拘急，重與芍藥甘草湯，爾乃脛伸). This line describes a disease of the sinews, which have become tense and malnourished due to a deficiency of yin fluids of the Liver.

The gathering, moistening and nourishing activity of Shaoyao is able to treat this, and it is further enhanced by the addition of Gancao, whose sweet flavor soothes urgency, in keeping with the principle of Su Wen Chapter 22, which states “”When the Liver suffers urgency, urgently eat sweet in order to relax it.” (肝苦急，急食甘以緩之). Together Shaoyao and Gancao simultaneously nourish the sinews and relax the Liver by moistening and replenishing Yin fluids.

Chi Shao, c/o Phoenix Medical

The formula Si Ni San (四逆散) can be understood as a combination of Shaoyao Gancao Tang and Zhishi Shaoyao San, with Chaihu added to more directly course and disperse stagnant Wood. Although Chaihu is typically considered to be the lead herb in this formula, the importance of Shaoyao as a Minister cannot be overstated.

Line 279 states:

本太陽病,醫反下之,因而腹滿時痛者,屬太陰也,桂枝加芍藥湯主之

When originally there was disease in the Taiyang, but the physician purges it, and consequently there is abdominal fullness with periodic pain, this belongs to the Taiyin. Guizhi Jia Shaoyao Tang governs it.

Guizhi Jia Shaoyao Tang consists of the same ingredients as Guizhi Tang, but the dosage of Shaoyao has been doubled, which directs the therapeutic action of the formula from the surface (the Taiyang) to the interior (the Taiyin, which also belongs to Earth). It treats abdominal pain by warming and opening the channels to relieve spasm.

If Yitang (飴餹) is added to Guizhi Jia Shaoyao Tang, it will greatly enhance the formula’s nourishing and fluid replenishing properties, and yield the formula Xiao Jian Zhong Tang (小建中湯), one of whose key indications is abdominal pain arising from qi and blood deficiency of the middle burner.

Line 100 states,

傷寒，陽脈澀，陰脈弦，法當腹中急痛者，先與小建中湯，不差者，與小柴胡湯主之

In cold damage, when the yang pulse is choppy and the the yin pulse is wiry, there is generally urgent pain in the abdomen, first give Xiao Jian Zhong Tang. If there is no cure, then give Xiao Chaihu Tang.

There is some debate over the pulse signs in this line should be interpreted, but general agreement that the symptoms of urgent, cramping pain in the abdomen can be understood in terms of Wood overacting on Earth. However, we must also differentiate whether this symptom is primarily one of deficiency (and thus is treated by Xiao Jian Zhong Tang), or primarily one of excess (and thus is treated with Xiao Chaihu Tang).

In both formulas, Zhang Zhongjing takes care to treat the Earth while treating Wood. In the case of Xiao Jian Zhong Tang, this takes center stage, but even in Xiao Chaihu Tang, whose primary action is coursing stagnant Wood, the Earth is protected with Renshen, Shengjiang, Dazao, and Zhi Gancao.

Lastly, it should be noted that in Line 96, an important modification of Xiao Chaihu Tang is to replace Huangqin with Shaoyao when there is a Xiao Chaihu Tang pattern with abdominal pain (若腹中痛者，去黃芩，加芍藥). Hopefully after this article, the reasoning behind this substitution will be clear.