By Eric Brand

Our local Blue Poppy hero, beloved blogger, and customer service demigod Shawn Kirby requested more on formula combining, with a special request for Wen Dan Tang. Wen Dan Tang is probably best discussed as a modification of Er Chen Tang, so here it is.

Follow up:

Er Chen Tang (Two Matured Ingredients Decoction)

Ban Xia (Pinelliae Rhizoma)
Chen Pi (Citri Reticulatae Pericarpium) or Ju Hong (Citri Reticulatae Pericarpium Rubrum)
Fu Ling (Poria)
Zhi Gan Cao (Glycyrrhizae Radix Praeparata)

Er Chen Tang is a representative base formula for patterns of dampness and phlegm. Er Chen Tang has a very clear direction and utilizes an eloquent combination of medicinals. It is thus one of the most fundamental formulas in a modular approach to formula combining, and it is very versatile when modified appropriately.

Er Chen Tang dries dampness and transforms phlegm while rectifying qi and harmonizing the center. The formula is based on the combination of Ban Xia and Chen Pi (or Ju Hong). Ban Xia is acrid, warm, and dry; it dries dampness and transforms phlegm while also harmonizing the stomach and downbearing counterflow. Chen Pi rectifies qi and moves stagnation while also drying dampness and transforming phlegm. When combined together, they are not only complementary in the sense that they increase the strength of drying dampness and transforming phlegm, but they also draw upon the principle of “[to] treat phlegm, first rectify qi, [when] qi is normalized, phlegm disperses.” This combination is also the origin of the formula name, because the superior products are aged, which gives them the advantage of not being excessively dry.

Fu Ling assists by fortifying the spleen and percolating dampness, which assists the transformation of phlegm. Fortifying the spleen helps treat the origin of the dampness. When combined with Chen Pi, the qi stagnation caused by phlegm is treated as well as the origin of the phlegm.

The addition of Sheng Jiang helps control the toxicity of Ban Xia, while also enhancing its ability to transform phlegm, harmonize the stomach, and relieve vomiting. In the original formula, a small amount of Wu Mei was used to constrain the lung qi to provide contraction within the dispersing effect and prevent damage to right from the dry, dispersing medicinals. Gan Cao fortifies the spleen and harmonizes the center, while also harmonizing the other medicinals. The overall formula is tightly constructed, and treats both root and branch, using both dispersing and constraining approaches. It dries dampness and rectifies qi to treat phlegm that is already formed, and it fortifies the spleen to treat the origin of the phlegm.

Er Chen Tang is particularly suitable to treat cases where the spleen is encumbered by dampness. Since spleen vacuity is often an underlying pathomechanism in the formation of dampness, Er Chen Tang is often combined with spleen-supplementing medicinals such as Bai Zhu (Atractylodis Macrocephalae Rhizoma) and Ren Shen (Ginseng Radix).

Er Chen Tang can also be used for vomiting in pregnancy (morning sickness). The simple addition of Zhu Ru (Bambusae Caulis in Taenia) to Er Chen Tang creates an unnamed formula from Sun Si Miao’s Qian Jin Fang (“Thousand Gold Formulary”) that is one of Chinese medicine’s earliest formulas for vomiting in pregnancy. Further adding Huo Xiang Geng (Pogostemi Caulis), Huang Qin (Scutellariae Radix), Sang Ji Sheng (Taxilli Herba), and Xu Duan (Dipsaci Radix) to this creates a useful modern empirical formula found in major Chinese gynecology textbooks for vomiting in pregnancy.

Alternatively, Er Chen Tang can be used in combination with Si Jun Zi Tang (Four Gentlemen Decoction) to create the principle of Liu Jun Zi Tang (Six Gentlemen Decoction), which simultaneously supplements the spleen and dries dampness. Cases with more severe damp encumbrance affecting the middle burner can treated by adding Mu Xiang (Aucklandiae Radix) and Sha Ren (Amomi Fructus), creating the principle of the formula Xiang Sha Liu Jun Zi Tang (Costusroot and Amomum Six Gentlemen Decoction). These other compound formulas are available on their own, but building them from combining base formulas provides additional versatility because the dosage of the different principles (drying dampness vs. supplementing the spleen) can be adjusted based on need.

In cases where damp encumbrance is more severe than qi vacuity, medicinals such as Cang Zhu (Atractylodis Rhizoma) and Hou Po (Magnoliae Officinalis Cortex) may be added to Er Chen Tang. This brings the principle closer to the formula Ping Wei San (Stomach-Calming Powder), which treats damp obstruction of the spleen and stomach.

Er Chen Tang can also be used along with spleen-fortifying medicinals such as Bai Bian Dou (Lablab Semen Album), Bai Zhu (Atractylodis Macrocephalae Rhizoma) and Yi Yi Ren (Coicis Semen) to treat cases where spleen vacuity is present but damp obstruction is prominent. With the proper modifications, Er Chen Tang can also be used to treat conditions such as cold damp patterns of vaginal discharge as well as conditions with cold phlegm in the upper burner.

Many traditional formulas are conceptually derived from Er Chen Tang. For example, the formula Dao Tan Tang (Phlegm-Abducting Decoction) is basically Er Chen Tang plus Zhi Shi (Aurantii Fructus Immaturus) and Tian Nan Xing (Arisaematis Rhizoma), which powerfully strengthen its ability to transform phlegm. Similarly, the formula Di Tan Tang (Phlegm-Flushing Decoction) can be built from Er Chen Tang. Di Tan Tang treats wind-stroke with phlegm confounding the orifices of the heart, and basically consists of Dao Tan Tang plus Zhu Ru (Bambusae Caulis in Taenia), Shi Chang Pu (Acori Tatarinowii Rhizoma), and Ren Shen (Ginseng Radix).

Several other commonly used formulas can be easily elaborated from Er Chen Tang. Using a few base formulas to create related formulas is particularly advantageous to practitioners that have constraints on space or capital, because many formulas can be created from a small number of base formulas. In addition to the formulas mentioned above, Er Chen Tang can also be used to create formulas such as Wen Dan Tang (Gallbladder-Warming Decoction), Qing Qi Hua Tan Wan (Qi-Clearing Phlegm-Transforming Pill), and Ban Xia Bai Zhu Tian Ma Tang (Pinellia, White Atractylodes, and Gastrodia Decoction).

Wen Dan Tang (Gallbladder-Warming Decoction) is a commonly-used formula to treat the pattern of depressed gallbladder with harassing phlegm. This pattern manifests in symptoms such as susceptibility to fright, dizziness, palpitations, insomnia, frequent unusual dreams, nausea, vomiting, and epilepsy. Wen Dan Tang is created by adding Zhu Ru (Bambusae Caulis in Taenia) and Zhi Shi (Aurantii Fructus Immaturus) to Er Chen Tang. For patients with concurrent heat symptoms, Huang Lian (Coptidis Rhizoma) can be added to this to make the formula Huang Lian Wen Dan Tang (Coptis Gallbladder-Warming Decoction).

For cases of phlegm-heat cough, the formula Qing Qi Hua Tan Wan (Qi-Clearing Phlegm-Transforming Pill) can be created from Er Chen Tang. To do this, simply add Zhi Shi (Aurantii Fructus Immaturus), Gua Lou (Trichosanthis Fructus), Dan Xing (Arisaema cum Bile), and Huang Qin (Scutellariae Radix) to Er Chen Tang. These additions help the formula target phlegm-heat in the upper burner.

To treat wind-phlegm harassing the upper burner, Er Chen Tang can be modified to form the formula Ban Xia Bai Zhu Tian Ma Tang (Pinellia, White Atractylodes, and Gastrodia Decoction). This formula is an important formula for wind-phlegm patterns of headache and dizziness. It can be created by adding Bai Zhu (Atractylodis Macrocephalae Rhizoma) and Tian Ma (Gastrodiae Rhizoma) to Er Chen Tang.

The core ingredients of Er Chen Tang can be found in even more complex formulas, such as Ding Xian Wan (Fit-Settling Pill), a major formula for epilepsy. Bao He Wan (Harmony-Preserving Pill), a key formula for food stagnation, can also be elaborated from Er Chen Tang. In fact, even formulas such as Huo Xiang Zheng Qi San (Patchouli Qi-Righting Powder) can be created from a base of Er Chen Tang.