Classical Dosages: Pandora’s Box

Xiao Chai Hu Tang Explored.

Many practitioners have a desire to practice Chinese medicine in a manner that is congruent with what has been done in the past. That is, many prefer formulas that are time-tested. The formulas from the Discussion of Cold Damage (Shang Han Lun), written around 1800 years ago, often fall into this category because not only do they form the foundation of herbalism as we know it, but they are still commonly used today. However, we must ask, what aspect has been time-tested? Has the formula itself been consistently used in a fixed manner demonstrating clinical efficacy? Or is it just the idea behind the formula, applied to ever-changing situations, that has stood the test of time? I think there are aspects of both that are true. An examination of dosages used over time for one of the most famous classical formulas, Minor Bupleurum Decoction (xiao chai hu tang), will give some insight into this issue, as well as provide some guidance as to how we might consider following the classics.

First, it should be pointed out that Chinese weights and measurements have historically lacked standardization and have seen numerous changes throughout the centuries. Thus, the dosages listed in classic texts and how they relate to one’s current measurement system has been a source of debate for centuries. For example, in the 17th century, Li Shizhen (1517-1592) said, “The liang of the ancients is the qian of today.” However, Zhang Jiebing (1563-1640), of the same time period, wrote, The liang of the ancients equals six of today’s qian.Thus, even within a time period where we think weights are consistent, we see major disagreements. Because of this, various doctors from different regions – as well as different time periods – used contrasting systems of measurement.This raises some very practical questions. For example, how many grams of Bupleuri Radix (chai hu) are in the formula Minor Bupleurum Decoction (xiao chai hu tang)? Modern texts recommend anywhere from 9 to 24g a day, yet key archeological data on weights and measures from the Han dynasty put a daily dose of Bupleuri Radix (chai hu) anywhere from 111-125g (from the source text) (Xiong, 2005, Li, 2005).There are many factors to consider on why dosages may change over time. They include changes in the constitutions of the patient populations, different living conditions and environmental factors, changes in measurement systems and the resulting confusion, and even differences in herb quality or proper herb identification itself. Although the ‘why’ is interesting and is certainly worth exploring, merely looking at the differences in dosages for the ingredients in Minor Bupleurum Decoction (xiao chai hu tang) is enlightening and brings up two interrelated points:1. There is little consistency in how famous texts / doctors (both past and present) understood the fundamental dosages of Minor Bupleurum Decoction (xiao chai hu tang). This is interesting because all of them had the original source text, which was (and is) often simultaneously cited. See table #1 and compare the doses.

2. More concerning than an across-the-board lowering of dosages (which actually happened in 1979[i]) is that the ratios between the herbs are dramatically different from source to source. That is, if we compare the dosage of Bupleuri Radix (chai hu) to the dosages of the other herbs in the formula, we see considerable divergences in the corresponding ratios. For example, the ratios of Bupleuri Radix (chai hu) to Scutellariae Radix (huang qin) are anywhere from a 1:1 to 1:2.66, and of Bupleuri Radix (chai hu) to Pinelliae Rhizoma preparatum (zhi ban xia), anywhere from 1:1 to 2:97 (see chart #2). The latter is a 197% difference in ratios. For whatever reason, different authors have very different opinions not only about how to interpret the original doses from the Discussion of Cold Damage, but also, what doses may be most appropriate for their patient population.

This is peculiar because classical experts often talk about the precise nature of Zhang Zhongjing’s formulas, and how a change in a single ingredients dosage can dramatically affect the nature and actions of a formula. Consequently, students are often warned not to mess with the doses, because they represent a master’s creation. Although I generally agree that changing an ingredients dose can dramatically change a formulas action, one cannot help asking, “what is the ‘correct’ or ‘original’ dose that we should follow?” Since this seems quite difficult to ascertain, how do we make sense of such a wide breadth of discrepancies in these dosages and the corresponding ratios?

One solution is to look at how famous doctors have used Minor Bupleurum Decoction (xiao chai hu tang) clinically. From case records, we see doses across the board from 6g to 125g of Bupleuri Radix (chai hu) a day. Even a doctor who states that there should be 24g of Bupleuri Radix (chai hu) in Minor Bupleurum Decoction (xiao chai hu tang) may use anywhere from 12g to 30g depending on the individual presentation. Other herbs are also adjusted depending on specific guidelines.

We know that Zhang Zhongjing made specific recommendations for modifications of Minor Bupleurum Decoction (xiao chai hu tang) based on various signs and symptoms, such as exchanging Trichosanthis Radix (tian hua fen) for Pinelliae Rhizoma preparatum (zhi ban xia) if there is pronounced thirst. This trend of modifying the core formula has continued throughout time. However, we also see guidelines for how to modify (increase and decrease) dosages by Discussion of Cold Damage (Shang Han Lun) experts.

For example:

… Actually, according to specific circumstances, it is suitable to increase and decrease [the doses of these herbs]. For example, when there is alternating fever and chills one will want to emphasize the [dose of] Bupleuri Radix (chai hu). If there is no alternating fever and chills, but there is only ‘fullness in the chest and ribside,’ or ‘bitter taste in the mouth and dry throat,’ then Bupleuri Radix (chai hu) dose can be reduced. However, Scutellariae Radix’s (huang qin) dose should never surpass Bupleuri Radix (chai hu). Originally, the dose of Pinelliae Rhizoma preparatum (zhi ban xia) was half a sheng. This larger dose was important because it was able to descend counterflow and stop vomiting, which was important for the original indication of “frequent vomiting (Li, 2005).”


Without this symptom, one might reduce the dose. Essentials from the Golden Cabinet also mentions, “If there is fever with frequent vomiting then Minor Bupleurum Decoction (xiao chai hu tang) masters it.” In this case, a large dose of both Bupleuri Radix (chai hu) and Pinelliae Rhizoma preparatum (zhi ban xia) should be used (Li, 2005). This is the type of thinking sits at the core of how famous doctors modify classic formulas and can arrive at dramatically different doses, and even different ratios of herbs. Of course there are a multitude of other variables to consider, such as the patient´s constitution etc.

Additional Thoughts:

All of this brings up an interesting point. Often, modern practitioners use classic formulas in ways that were not originally prescribed. For example, the original indication of alternating fever and chills for Minor Bupleurum Decoction (xiao chai hu tang) was most likely quite severe, possibly akin to malaria. A large dose formula, e.g. using 100g of Bupleuri Radix (chai hu), makes sense in this context.

However, modern practitioners often extrapolate this symptom to represent a condition that comes and goes (and various other ideas related to it). Consequently, they might give Minor Bupleurum Decoction (xiao chai hu tang) to a patient that does not exhibit the severity of the original presentation. In addition, it may be based on their constitution, abdominal or pulse confirmation, which traditionally might not necessary have been used (in the manner we use it today). Such adaptation is, of course, valid, but the reality is that the patient in front of us may look different than what this formula was originally intended for. Therefore, Minor Bupleurum Decoction (xiao chai hu tang) may be given in a smaller dose – and over a long period of time – quite successfully.

Finally, the method of preparation originally recommended in the Discussion of Cold Damage (Shang Han Lun) differs from the way many of us prepare decoctions. The source text advises to decoct the ingredients in approximately 12 cups of water (originally one dou and two sheng) until six cups remain. The dregs are removed and the strained decoction is further decocted until three cups remain. This additional cooking time – especially without the herbs themselves – tempers the larger dose of e.g. Bupleuri Radix (chai hu). Therefore, when I use larger doses of Bupleuri Radix (chai hu), I have the patient prepare their herbs in this manner.

Both of these points help understand how a 111-125g of Bupleuri Radix (chai hu) might have made sense classically, while the majority of our current Minor Bupleurum Decoction (xiao chai hu tang) patients would just not do well with such doses. Even a 24-gram-a-day dose is daunting for most practitioners, in both China and the West.


In conclusion, there has been a quite a bit written over the centuries about Minor Bupleurum Decoction (xiao chai hu tang), and the numerous ways it can be used. Quite simply, its usage as well as the dosages of its ingredients has changed over time. If we want to try to find a starting point that is close to Zhang Zhongjing´s original thinking, we might forgo trying to nail down the exact doses and try to follow the ratios from the source text as closely as possible. This is a good starting point and the following formula represents these ratios:

  • Chai Hu24g
  • Huang Qin9g
  • Ren Shen9g
  • Zhi Gan Cao9g
  • Ban Xia8g
  • Sheng Jiang9g
  • Da Zao6g (rounded up from 5.75)

Apart from this, stay nimble.

Note: After this research Red Pine Chinese Herbs have changed their dose Xiao Chai Hu Tang to the above.

Table #1 – Doses of Ingredients for Xiao Chai Hu Tang – converted to grams.

Chai Hu Huang Qin Ren Shen Zhi Gan Cao Ban Xia Sheng Jiang Da Zao
SHL(1) 125g[ii] 46.875g 46.875g 46.875g 42g[iii] 46.875g 30g
SHL(2) 111.36g[iv] 41.76g 41.76g 41.76g 100ml[v] 41.76g ?
Xu Shu-Wei (1075-1156) 74.7g 3 fen[vi](分) 3 fen 3 fen 22.41g 5 slices 2p
Shang Han Wen Yi Tiao Bian 1748 14.92g 7.46g 3.73g 3.73g 7.46g 7.46g 2p
Zhang Xi-Chun (1909) 29.84g  11.19g 11.19g 11.19g 14.92g 11.19g 4p
实用中医学 1975 11.19g[vii] 7.46g 3.73g 3.73g 11.19g 11.19g 4p
中医方剂手册 1983 9g[viii] 9g 9g 9g 6g 9g 4p
实用方剂小典  2002 12g 9g 6g 5g 9g 9g 4p
Fangji Xue (2005) 24g 9g 9g 9g 9g 9g 4p
Huang Huang (2005) 10-20g 6-10g 5-10g 5-10g 6-15g 10-15g 5-10p
Scheid/Bensky (2009) 24g 9g 9g 9g 24g 9g 12p


Table #2 – Ratios of herbs with Chai Hu[ix]

Chai Hu Huang Qin Ren Shen Zhi Gan Cao Ban Xia Sheng Jiang Da Zao
SHL(1) 2.67 2.67 2.67 2.97 2.67 4.166
SHL(2) 2.67 2.67 2.67 ? 2.67 ?
Xu Shu-Wei (1075-1156) ? ? ? 3.33 ? ?
Shang Han Wen Yi Tiao Bian (1748) 2 4 4 2 2
Zhang Xi-Chun (1909) 2.67 2.67 2.67 2 2.67 ?
实用中医学 1975 1.5 3 3 1 1 ?
中医方剂手册 1983 1 1 1 1.5 1 ?
实用方剂小典 2002 1.33 2 2.4 1.333 1.333 ?
Fangji Xue (2005) 2.67 2.67 2.67 2.67 2.67 ?
Scheid/Bensky (2009) 2.67 2.67 2.67 1 2.67 ?


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