Preview of Formula Modifications

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Introduction

The Shang Han Lun (Treatise on Cold Damage) is not merely a collection of formulas, but a sophisticated clinical system that reveals how disease transforms, how treatment alters physiology, and how herbs function dynamically within formulas rather than as isolated substances. One of the most effective ways to enter this system is through the study of formula modifications, where small changes in composition reflect precise shifts in pathology, conformation, and the balance of Yin and Yang.

This text explores a series of classical modifications primarily based on Gui Zhi Tang and related formulas, as recorded in the Shang Han Lun and interpreted through traditional commentaries, including insights from Todo Yoshimasu’s Yakuchō. By examining why individual herbs are added, removed, or dosed differently, we gain a deeper understanding of disease progression across the Tai Yang, Yang Ming, Shao Yang, Tai Yin, and Shao Yin conformations.

Rather than relying on rote memorization, this approach emphasizes pattern dynamics, fluid metabolism, and the functional roles of herbs within the cosmological and physiological framework of Classical Chinese Medicine. Each modification becomes a clinical lesson in how the body responds to both disease and treatment, and how the physician must respond in turn.

This text presents an in-depth examination of formula modifications in the Shang Han Lun, demonstrating how subtle changes in herbal composition correspond to shifts in disease mechanism, conformation, and the balance of Yin, Yang, Qi, Blood, and fluids.

Key themes include the restoration of Yang after improper sweating, the transformation and movement of fluids, the anchoring of unrooted Yang, and the correction of counterflow in the Lung and Stomach. The text highlights how misapplication of sweating, purging, or vomiting therapies can drive disease inward, creating complex patterns of vacuity, heat, dampness, or phlegm, and how classical formula adjustments address these changes with precision.

Modifications

14 When in Tai Yang disease there is stretched stiff nape and back, but also sweating and aversion to wind, it is treated with gui zhi jia ge gen tang.

Gui zhi jia ge gen tang is a modified version of gui zhi tang. Gui zhi tang is being used to restore the Yang of the body, on the surface as well as internally. Gui zhi tang is treating the Tai yang wind strike disease, which is a deficiency disease. It is called a deficiency disease because something is missing. Yin fluids are missing.

Adding ge gen, which is Puerariae radix, does two basic things. One it tonifies Yang qi, and two it nourishes Yin fluids.

Ge gen is sweet, which nourishes Yin.

Ge gen is pungent , which tonifies Yang.

Ge gen strengthens the Earth’s functions by tonifying the Spleen Yang. This can stop diarrhea if present. This tonifying raises clear qi up to the Heart and Lungs to be dispersed over the body. This has a nourishing effect of all the Yang in the body.

The key to understanding ge gen is that it tonifies Earth, and nourishes the muscles in the neck and back. This treats the stretched stiff nape and back, it also replaces the lost fluids from sweating.

Todo Yoshimasu wrote the Yakucho, a text that expressed the Kohoha School's original theories on the therapeutic effects of medicinal plants in Shokanron and Kinki-yoryaku. Todo Yoshimasu, is considered to be one of the most influential figures in the history of Kampo medicine. Known for his positivistic Kampo approach, Yoshimasu was known as willing to accept and use any technique so long as it proved clinically effective. 

The Yakucho has this to say about ge gen. It governs the treatment of rigidity of the neck and back. On the side it treats panting with sweating.

If a patient presents with a Tai yang wind strike pattern, ask about the tightness and pain of the upper back and neck. Also ask about the function of the Stomach.

Adding ge gen to gui zhi tang can be done in most cases, especially if there is a history of dryness in Earth, reflected in dry tight muscles.

Yang ming represents dryness in the body, and Tai yin represents dampness in the body. Ge gen adds dampness to Tai yin which moistens the Yang ming.

Ge gen is used in other formulas, namely ge gen tang and ben tun tang.

18 For panting patients suffering from gui zhi tang pattern, it is best to add hou po and xing ren.

Adding hou po and xing ren to gui zhi tang creates the formula gui zhi jia hou po xing zi tang. This formula is also known as gui zhi jia hou po xing ren tang.

The use of hou po and xing ren is also mentioned in line 43.

Line 43 When in tai yang disease, there is mild panting following precipitation, it means that the exterior has not yet resolved, therefore gui zhi jia hou po xing zi tang governs. 

Gui zhi tang treats a Tai yang wind strike pattern. In a Tai yang wind strike pattern all the Yang of the body has become weak and unanchored, both externally and internally. The weak Yang internally gives rise to an accumulation of fluids and heat. This is due to a failure of the weak Yang to transform fluids, and descend. The Lung has become weak and lost it normal function of dispersing and descending fluids. This give rise to panting.

Adding Hou po, Magnoliae cortex, does three things. One it opens the chest, two it opens the middle, three it transforms phlegm, which is a thicker form of dampness.

The Yakucho has this to say about hou po. It governs the treatment of distension and fullness of chest and abdomen. On the side it treats abdominal pain.

Hou po is warm Yang tonifying.

Hou po is bitter descending.

Hou po is aromatic dispersing.

Hou po brings Yang to Earth, and this opens the upper and middle burner. It transforms the excess dampness, and pushes downward. By clearing the pivot of Earth, the normal function of the Lung is restored and panting due to the accumulation of heat is stopped.

Hou po is also used in other formulas namely, hou po san wu tang, and zhi shi xie bai gui zhi tang.

Adding Xing ren, Armeniacae semen, does three things. One it descends the Lung, two it transform dampness, and three it moistens dryness.

The Yakucho has this to say about xing ren. It governs the treatment of water stagnant in the chest. And therefore it can treat panting and cough, on the side it treats shortness of breath and chest bind, heart pain, and superficial swelling of the body.

Xing ren is warm tonifying of Yang qi, and warming of fluids.

Xing ren is bitter descending of excess fluids and the Lung and Stomach family of the Small Intestine, and Large Intestine organs.

Xing ren is sweet moistening of dryness, especially of the Large Intestine.

The key to understanding xing ren is that it is bitter descending of the Metal mandate which opens the Lungs and Large Intestine.

Xing ren  is also used in other formulas namely, ma huang tang, ma zi ren wan, fu ling xing ren gan cao tang.

20 When in Tai Yang disease, sweating is promoted and then gives way to incessant leaking, the person is adverse to wind, has difficult urination, and the limbs are tensed so that they bend and stretch with difficulty, gui zhi jia fu zi tang governs.

Adding fu zi to gui zhi tang creates the formula gui zhi jia fu zi tang.

When we promote sweating as a therapeutic solution there is the chance we cause excessive sweating. It is better to think about promoting sweating as restoring the ability to sweat. If the body loses its ability to close the pores of the skin incessant leaking of sweat occurs.

Remember that sweat is a fluid of the Heart. Incessant leaking weakens all the Yang of the body and gui zhi tang alone will not be strong enough to restore the internal Yang, so fu zi is added.

Adding Fu zi, Aconiti radix lateralis praeparata, which is also known as zhi fu zi does one thing. It brings Yang Fire to Water to transform fluids of the Kidney.

The Yakucho has this to say about fu zi, It governs the driving out of water, and so it can treat aversion to cold, with pain of the body, four extremities and joints, possibly with heaviness, or numbness, or reversal cold, while on the side treating abdominal pain, loss of semen and downpour diarrhea.

Fu zi is warm pungent tonifying of Yang.

Fu zi directly warms the Shao yin Fire allowing it to warm and produce Kidney vapor which rises up to the Heaven to warm the surface. 

It warms the Original qi of the Kidneys and the Gathering qi of the Lungs and Heart. Fu zi infuses the body with fire and promotes water metabolism through the descent of Fire into the Water reservoirs of the body. 

The key to understanding fu zi is that it brings Fire to Water. It shines like the sun to transform and move fluids. 

This is the perfect time to discuss and compare gui zhi and fu zi. 

The combination of fu zi and gui zhi is the strongest in promoting water metabolism by warming cold fluids. 

Gui zhi and fu zi are the emperors in the herbal world. By restoring the function of Yang they put the emperor back on his throne so he may rule the kingdom with ease.

Gui zhi rules without causing unrest. Fu zi rules with might and action. Gui zhi nourishes with its sweat nature and fu zi does not. Fu zi disperses more than gui zhi and needs to be controlled. Gui zhi warms the Tai yang bladder to warm the Shao yin Kidney Water. Fu zi directly warms the Shao yin Kidney Water.

Fu zi is also used in other formulas namely, fu zi tang, si ni tang, gui zhi fu zi tang.

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