"Mendong Yinzi": A Formula for Thirst and Dry Cough
The formula "Mendong Yinzi" appears in several sources. In "Zheng Yin Mai Zhi" (Treatment of Disease Causes by Symptom, Pulse, and Pattern), it consists of Tiandong (Asparagus root), Maidong (Ophiopogon), Sangbaipi (Morus bark), Zhiqiao (bitter orange), Jiegeng (Platycodon), Jingjie (Schizonepeta), and Gancao (Licorice), in appropriate amounts. Taken as a water decoction, it nourishes yin and moistens dryness, transforms phlegm and stops cough. It treats cough due to dryness injury, with thirst and parched lips, vexatious heat demanding drink, phlegm that cannot be expectorated, or phlegm streaked with blood, blood in urine and stool, and panting cough. If the stool is bound, add Dahuang (Rhubarb); if phlegm is abundant, add Beimu (Fritillaria).
In "Yixue Rumen" (Introduction to Medicine) there is also a formula called "Mendong Yinzi," composed of Maidong (Ophiopogon), Renshen (Ginseng), and Zhimu (Anemarrhena), each one qian; Shengdihuang (raw Rehmannia) eight fen; Fushen (Poria-Sclerotium) seven fen; Wuweizi (Schisandra), Gualouren (Trichosanthes seed), and Gegen (Pueraria), each five fen; Gancao (Licorice) three fen; and seven bamboo leaves. Also taken as a water decoction, it treats "heart fire transmitted to the lung, diaphragmatic wasting with chest fullness, vexation, and dry fluids demanding drink."
In addition, "Shanghan Dabai" (Great Primer on Cold Damage) has a Mendong Yinzi composed of Maidong (Ophiopogon), Digupi (Lycium bark), Zhimu (Anemarrhena), Shigao (Gypsum), Shengdi (raw Rehmannia), Danpi (Moutan), and Baishao (White Peony); this one treats epistaxis (nosebleed).
The formula introduced here is the Mendong Yinzi from "Zheng Yin Mai Zhi," which does not specify dosages. A clinical base dose may be: Maidong (Ophiopogon) 10 g, Tiandong (Asparagus) 10 g, Sangbaipi (Morus bark) 10 g, Chao Zhiqiao (stir-fried bitter orange) 3 g, Jiegeng (Platycodon) 10 g, Jingjie (Schizonepeta) 6 g, Sheng Gancao (raw Licorice) 6 g; if the stool is dry and bound, add Dahuang (Rhubarb) 3-10 g.
In this formula, Maidong moistens the lung and nourishes yin; Tiandong clears lung heat and downbears fire; Sangbaipi drains lung excess and calms wheezing; Jiegeng diffuses the lung and stops cough; Gancao expels phlegm and stops cough. All stop cough and each has some yin-nourishing, dryness-moistening action. Jingjie releases the exterior through sweating and expels wind pathogen to treat the root. Stir-fried Zhiqiao moves qi and broadens the middle; it both disperses accumulated qi in the chest and prevents the cloying, diaphragm-obstructing nature of Maidong and Tiandong. Its inclusion is the finishing touch—this is the refinement of TCM formulation: in a good prescription, the herbs complement one another, enhancing the therapeutic effect while reducing side effects.
This formula can relieve dry mouth and throat and persistent cough in patients with upper respiratory diseases such as lung cancer, pneumonia, and bronchitis. Some lung cancer patients (in my clinical experience, chiefly small-cell lung cancer patients) suffer severe dry mouth; such patients may use this formula for symptomatic relief.
In my experience, when using this formula to relieve thirst and dry cough in lung cancer and nasopharyngeal carcinoma patients, one may also add Huangqin (Scutellaria) 10 g, Digupi (Lycium bark) 10 g, Xianhecao (agrimony) 30 g, Xingren (apricot kernel) 6 g, and Yiyiren (Coix seed) 30-60 g. But this formula is only for symptomatic management of lung and nasopharyngeal cancer; its effect on controlling tumor growth is limited. Treating the tumor still requires combining it with radiotherapy, chemotherapy, or other antitumor Chinese herbs.