"Dihuang Jian Wan" in Waike Jingyi (The Essence of External Medicine)
In the lower volume of "Waike Jingyi" (The Essence of External Medicine) by Qi Dezhi, the Yuan-dynasty master of external medicine, there is a formula called "Dihuang Jian Wan" (Rehmannia Decoction Pills). It treats malignant sores, toxic abscesses, and bound, difficult urination and defecation. Its ingredients are: fresh Rehmannia (ten liang of the new crop, washed, soaked in water and ground to a paste); Coptis (Huanglian), five liang; Scutellaria (Huangqin, decayed parts removed), three liang; Zhiqiao (bitter orange, stir-fried, pulp removed) and raw Rhubarb (Dahuang), each two liang five qian; and Ginseng (Renshen), two liang.
This is a pill formula, not a decoction. Preparation: grind the five herbs other than fresh Rehmannia into a fine powder; decoct the Rehmannia, mix the resulting liquid with the herb powder, add boiled honey, and form into pills. The pills are pea-sized; take fifty to seventy (50-70) pills each time after meals, washed down with warm water.
"Waike Jingyi" says this formula treats "heat in the viscera, phlegm-repletion in the chest and diaphragm, disharmony of qi and blood, binding and dryness in the channels and collaterals, frequent outbreak of sores and swellings; for those already suffering malignant sores and toxic swelling with bound, difficult urination and defecation." It adds: "People with constitutions accustomed to heat, taking over a hundred pills daily, will not develop sores. Elderly, weak people should also take it regularly to clear and disinhibit the chest and diaphragm and brighten the eyes."
This formula is in fact an addition to Sanhuang Xiexin Tang (Three-Yellow Heart-Draining Decoction) from Zhang Zhongjing's "Jingui Yaolue" (Essential Prescriptions from the Golden Coffer). Sanhuang Xiexin Tang consists of Rhubarb, Coptis, and Scutellaria; in traditional TCM theory it drains fire and resolves toxin, dries dampness and discharges heat, and belongs to the heat-clearing category. Dihuang Jian Wan adds Ginseng, fresh Rehmannia, and Bitter Orange, and changes the decoction into a pill. The meaning is: chronic disease is treated gradually with pills; while dispelling pathogen, healthy qi is supported; fire-draining is combined with qi-regulating and stagnation-resolving.
Ginseng strongly supplements original qi and, for those long ill or aged and weak, supports healthy qi and secures the root. Fresh Rehmannia both nourishes yin and cools blood, and disperses stasis and reduces swelling—supporting healthy qi while dispelling pathogen. Bitter Orange regulates qi and broadens the middle, moving stagnation and reducing distention. Combining these three with Sanhuang Xiexin Tang both strengthens the latter's heat-draining, swelling-reducing force and fills its deficiencies; attack and supplementation are used together. This modification captures the essence of TCM external medicine: external symptoms arise from internal damage; to treat the exterior, one must first pacify the interior.
Modern pharmacological research has found that Sanhuang Xiexin Tang has good anti-infective and antitumor effects. So this formula is effective both for infectious heat-excess swelling and pain (such as acne, impetigo, and tonsillitis) and for tumor patients presenting the heat-excess pattern. How does one judge whether a patient fits the heat-excess pattern? I believe the key lies in the five characters "urination and defecation bound and difficult"—that is, short, dark, hard urination and constipation. This is the most objective treatment indication. Grasp this main contradiction, and this formula is on target.