Any formula that contains two herbs or less is a teeny tiny formula in my book. (Not that I’ve written my book yet!) Within Gui Zhi Tang there are two teeny tiny formulas. The beauty of knowing these teeny tiny formulas is that they shed immense light on the function of a larger formula that contains them. Gui Zhi Tang itself is a small formula with just five ingredients. It is interesting that such a small formula can still house two more formulas inside it.
In this post I’ll discuss which formulas are in Gui Zhi Tang and give a general discussion of what they are doing in there. This post is the first in a series. The next post will offer discussion and case studies about the first formula and the post after that will focus on the other formula. Wow, at the end of these posts you are going to really know Gui Zhi Tang inside and out. The teeny tiny formulas are also suprisingly useful in the clinic by themselves.
Below are discussions by myself and then by two Chinese doctors about these formulas. Both of them emphasize the fact that Gui Zhi Tang not only harmonizes the Ying and Wei but also harmonizes Qi and blood and Yin and Yang. It is through the action of these two teeny tiny formulas that Gui Zhi Tang’s action goes beyond harmonizing the Ying and Wei.
Gui Zhi Gan Cao Tang uses sweet and pungent to “transform Yang.” Shao Yao Gan Cao Tang uses sweet and sour to “transform Yin.” What does it mean to transform Yin and Yang here? We have the sense that they are untransformed and need transforming. What does this mean? How do sweet and pungent work together to transform Yang and how do sweet and sour work together to transform Yin? Why is it that sweet licorice is the common flavor between these two formulas?
To start we can look at the common denominator of these two formulas: Gan Cao. Gan Cao is the sweetest herb in the pharmacopeia. It is really the essence of sweetness. The sweet flavor nourishes. In both the Tang Ye Jing and Neijing, the sweet flavor is said to supplement the spleen. Supplementing the spleen with sweetness means to add substance, bring in more good stuff.
When sweet Gan Cao is combined with pungent Gui Zhi, we can liken this to putting a fire (Gui Zhi) under a cooking pot that is filled with water, potatoes and carrots (Gan Cao). This is because the pungent flavor ascends and Gui Zhi is warm as well, so it is like a gentle fire going into the spleen earth. “Transforming Yang” means to not only increase Yang but to give Yang substance to inhabit and warm. Hot soup is cold water and vegetables that have been transformed by fire into something nourishing. This is how sweet and pungent “transform Yang.” Untransformed Yang is Yang that has not been strong enough to penetrate cold Yin and transform it into warm steam.
When the sweet Gan Cao is combined with the sour, bitter, cool Bai Shao, there is a somewhat opposite action. Substance is added with the Gan Cao’s sweetness and then the sour, bitter quality of Bai Shao moves that substance downward into the interior (bitter), and keeps it there (sour) – thereby enriching substance or Yin. Untransformed Yin is Yin that is not abundant enough and also not well contained. Shao Yao Gan Cao Tang transforms Yin by nourishing Yin, bringing it inward and keeping it there.
When Gui Zhi Gan Cao Tang is combined with Shao Yao Gan Cao Tang both Yin and Yang are transformed. This is how Gui Zhi Tang transforms Yin and Yang. Since Yang within Yin is the root of the Qi within the blood, Gui Zhi Tang also harmonizes Qi and blood. Since the Qi within the blood is the root of the Ying and Wei, Ying and Wei are also harmonized by Gui Zhi Tang.
Gui Zhi Tang regulates and harmonizes the Ying and Wei. The foundation of this is the regulation and attention to Yin and Yang. Gui Zhi Tang contains Gui Zhi Gan Cao Tang. In this formula, pungent and sweet transform the Yang. It also contains Shao Yao Gan Cao Tang in which sour and sweet transform the Yin. When Yin and Yang are harmonized, the exterior and interior are also harmonized. Therefore Gui Zhi Tang not only treats contraction of and exterior evil, it also treats miscellaneous illnesses.
Cinnamon Twig Decoction (guì zhī tāng) is the first formula mentioned in the Discussion of Cold Damage (Shāng hán lùn) and is the ancestor of all formulas. Within the formula are two others, Cinnamon Twig and Licorice Decoction (guì zhī gān cǎo tāng) and Peony and Licorice Decoction (sháo yào gān cǎo tāng). The former is acrid and sweet; it transforms yang to adjust yin. The latter is sour and sweet; it transforms yin to adjust yang. The combination of the two gives Cinnamon Twig Decoction (guì zhī tāng) the capacity to adjust and harmonize the yin and yang of the entire body. In regard to the body, yin and yang relate to the blood and qi, and blood and qi relate to the nutritive and protective aspects. The ancients glowingly praised the ability of Cinnamon Twig Decoction (guì zhī tāng) to address external disorders by releasing the muscle layer and harmonizing the nutritive and protective aspects, and to address internal disorders by transforming qi and adjusting yin and yang. From a clinical viewpoint, a large number of chronic, stubborn, and complex patterns are lingering and difficult to cure. Although they have a complex disease origin and disease dynamic (equally so based on a Western medical etiology), in the final analysis these disorders fall into the category of disharmony between the nutritive and protective aspects. This disharmony may be between the blood and qi, between the yin and yang, or a combination of the two.
 From Collected Classic Formula Case Studies from Renowned Physicians, complied by Chen Ming and Zhang Yin-Sheng, 1998, Xue Yuan Publishers, Bei Jing
 A Walk Along the River, Transmitting a Medical Lineage through Case Records, by Yu Guo-Jun, Translated by Andrew Ellis, Michael Fitzgerald and Craig Mitchell, Eastland Press, 2017