Xiao yao san is one of the first formulas we learn, and probably one of the 10 essential formulas we need to know to practice Chinese medicine. It is also a very common formula to treat menstrual problems and depression in women.
It did not make sense to me why you needed to release the exterior when you were trying to stop the liver from invading the spleen. Of course, I would prescribe it when the pattern indicated its use and would get great results when I did. In fact the name of this article comes from my patients who nicknamed xiao yao san "happy pills," because it made them feel so damn good when they took it.
So with both of these questions in mind, I hit the textbooks (mostly Bensky and Gambles' Materia Medica and Bensky and Barolets' Formulas and Strategies). The general assumption I made was that the great and wise masters who developed the formulas we are looking at today knew what they were doing and crafted elegant and immensely practical formulas. (We will be looking at bu zhong yi qi tang, too.) Also, I assumed we could learn something about Chinese medicine by trying to figure out what these masters were thinking when they created these formulas. During my research, I discovered many interesting things.
The answer to the first question is simple enough if you focus on the other main indication for xiao yao san: fatigue. One reason chai hu is used is because the formula treats the liver overacting on the spleen. What happens when the spleen qi gets disrupted? It goes down instead of up. The rising action of chai hu is used to help nudge the spleen upward and back to normal function. Once the spleen is back to raising clear qi, it can go back to making qi and treating fatigue. That answers my first question, but not the second.
So, just why are there so many herbs in xiao yao san that are pungent and expel the exterior? It did not make sense to me. Why disperse wei qi if you are trying to relieve liver qi stagnation? Why not use chuan lian zi? It relieves constrained liver qi, is more cooling and dries damp - both the constrained heat and the dampness being common complications of spleen disharmony due to liver overacting.
Part of the problem is that chai hu does not really release the exterior in the same way as bo he, even though it is in the category of herbs that release exterior wind. Chai hu harmonizes the interior and exterior and helps the body rid itself of a shao yang-level disease. Even though this clarification is good and generally useful, it does not answer my initial question about the pungent wei qi -releasing character of chai hu, bo he and sheng jiang in general.
It is possible chai hu, bo he and sheng jiang are used in xiao yao san in spite of their exterior-releasing qualities, not because of them. However, that answer did not sit quite well with me. I did not believe it was just coincidence that in xiao yao san, a formula that has nothing to do with releasing the exterior, three of the eight herbs were in the category of releasing the exterior. My guess was that the Imperial Medical Department that probably created the formula had something more in mind, and I just could not see it yet.
While pondering this, I noticed that similar herbs are used in a similar manner in another formula, bu zhong yi qi tang. Instead of treating liver overacting on the spleen, the formula is used to treat qi deficiency, especially qi prolapse. So here I had the same conundrum I wrestled with earlier. Why did two of the three rising-action herbs used in bu zhong yi qi tang - chai hu and sheng ma - also release the exterior? The description of the formula is to help raise spleen qi and treat sinking symptoms. What does expelling wei qi have to do with uprising spleen qi?
The explanation in the textbooks of both xiao yao san and bu zhong yi qi tang did not touch on this aspect at all. Maybe the herbs' rising actions work like jie geng to move upward to help unblock and regulate lung functions. TCM herb use is littered with examples of using herbs with opposite actions to help regulate an organ's function. For example, the inward astringing action of sun zoo ren combined with the outward expanding action of yuan she help wonderfully to regulate the heart and shen.
But if that is the case, why not use jie geng in bu zhong yi qi tang, instead of sheng ma? Jie geng is used much more often than sheng ma when you want to guide herbs upward to the throat or lung. Would it not make sense to use it in bu zhong yi qi tang? However, jie geng is pungent and disseminates the lungs to help expel phlegm. It does not expel the exterior like sheng ma and chai hu. My guess is it is the dissemination of wei qi that helps to regulate the lung that is more important somehow.
A possible answer came to me while I was walking my dog and breathing in the relatively clean air of the park: the lung. If you remember, the three main organs involved in qi production are the spleen, lung and kidney. The two that we can have the quickest most direct effect on are the two post-heaven organs, spleen and lung. So if you are trying to treat the main manifestation of qi deficiency, fatigue, would it not make sense to treat the two organs that are most involved in the daily making of qi? My guess is that somehow regulating both the descending and dispersing function of the lung is key in helping it function better in general. It therefore produces qi better to help alleviate fatigue. Hence the wei qi-dispersing action of sheng ma and chai hu and not the use of jie geng. To confirm this idea, I went back and hit the textbooks again.
In reading the indication list in Bensky and Barolets' Chinese Herbal Medicine Formulas and Strategies for Bu Zhong Yi Qi Tang (p. 241), the actions listed are tonifying qi of middle burner and raising sunken yang. However, many of these indications are lung in origin: intermittent fever worse upon exertion, spontaneous sweating, aversion to cold, shortness of breath and laconic speech (half the symptoms listed). Of the herbs listed, only two of the eight (bai zhu and dang gui) do not affect the lung as well as the middle jiao.
Even though the main cause of the problem treated here is clear qi sinking or not rising, it appears Li Dong Yuan saw that a major effect of the qi not rising is to disrupt lung function. Even the explanation of the formula in the text mentions yang qi as unable to circulate to the superficial levels of the body, fluid metabolism problems in the upper body leading to thirst, aversion to cold due to inability of yang qi to circulate and support wei qi, plus the shortness of breath and weak speech, which are all lung functions. It looks like, by using the exterior-releasing herbs and in the indications list, Li Dong Yuan was saying that when you are treating fatigue and helping the body produce post-heaven qi, it is prudent or even necessary to treat both the lung and the spleen simultaneously to get the best effect. Also treat and regulate the wei qi production/spreading aspect of lung function in order to best produce qi and treat energy loss and fatigue.
I started out writing this column with questions about using pungent and rising herbs in xiao yao san and ended up looking at and speculating as to the role of the lung-regulating and tonifying herbs in bu zhong yi tang in treating fatigue. One of the things I love about TCM is that not only do we learn about how masters diagnose, treat and build formulas, but we also have the flexibility to apply our own experience in finding our way through. I know that when I go to any continuing education course or read a text, the part I find most interesting and useful is understanding not just how but why a practitioner treats or diagnoses the way they do. Hopefully, sharing my own exploration into how Li Dong Yuan and the Imperial Medical Department possibly formulated bu zhong yi qi tang and xiao yao san will stimulate discussion and debate on two very fundamental formulas whose originators are no longer around to ask questions of.
Click here for previous articles by Kaleb Montgomery, DTCM.