Xie Fei Tang: The Lung-Purging Decoction for Cough and Dyspnea
Waitai Miyao (Essentials from the Medical Heart) quotes a formula called Xie Fei Tang (Lung-Purging Decoction) from Xuangan Chuan Shi Fang (The Mysterious Transmission Corpse-Invocating Formula). It consists of Tinglizi (descurainia/lepidium seed) 3 qian (9 g, stir-fried over low heat until purplish, pounded into a paste), 30 Chinese jujubes (dazao), and Sanggen Baipi (mulberry root bark) 3 qian (9 g, sliced). First boil the mulberry bark and jujubes together in 3 bowls of water (about 900 ml) down to 1 bowl (about 300 ml), then add the tinglizi paste, stir well, and bring to a boil again, finally yielding about one-third of a bowl (roughly 100 ml). Take it warm. After taking the medicine the patient may vomit up foul material and may have "mild purgation" (light diarrhea) once or twice. Once these reactions occur, the symptoms will be markedly relieved.
Xie Fei Tang purges the lung and expels phlegm. It is indicated for "lung atrophy" (fe wei). The medication signs are cough with counterflow qi, inability to lie flat, and abundant sticky phlegm. "Lung atrophy" is a traditional Chinese medicine (TCM) disease name; the late-stage clinical picture of various modern chronic lung diseases (such as pulmonary tuberculosis, bronchitis, asthma, and lung cancer) closely resembles TCM "lung atrophy." Patients cough frequently, have sticky phlegm that is difficult to expectorate, cannot lie down, and find it hard to sleep even when sitting or reclining; some also have pleural effusion. Xie Fei Tang may not cure such patients, but as a symptomatic formula it can relieve symptoms and ease their suffering.
In this Xie Fei Tang from Waitai Miyao, the tinglizi must be ground into a paste. In fact this formula is Tinglili Dazao Xie Fei Tang (Descurainia and Jujube Lung-Purging Decoction) with the addition of mulberry bark. TCM holds that tinglizi purges the lung, calms wheezing, and promotes diuresis to reduce edema; it is commonly used for pleural effusion and generalized edema. Modern TCM prescriptions also use tinglizi, but most people simply decoct the seeds directly, which is problematic. As a kernel-type medicinal, tinglizi does not readily release its active constituents when decocted whole; pounding it into a paste yields a better effect.
There is also a formula of the same name in Shengji Zonglu (General Collections on Imperial Medicine). The Xie Fei Tang in that text is made of equal parts mulberry root bark and tinglizi; the mulberry bark is filed into pieces and the tinglizi is stir-fried yellow between sheets of paper. The two are jointly ground into a coarse powder. Each time take 3 qian (9 g) in 1 zhan of water (about 150 ml), decoct to six-tenths (about 90 ml), strain, and take warm. Again the aim is mild purgation. The Xie Fei Tang recorded in Shengji Zonglu treats lung abscess (fei yong, roughly comparable to lung atrophy) with dyspneic breathing, unable to sit or lie. This formula is basically similar to the Xie Fei Tang in Waitai Miyao, with similar actions.
Modern patients may use a grinder or mill to mix equal parts mulberry bark and tinglizi (the tinglizi should be stir-fried yellow to reduce its toxicity; tinglizi has some toxicity, which stir-frying lowers) into a powder. At each dose take 10-15 g of the powder, wrap it in a non-woven bag, and decoct in water. Add 150 ml of water and decoct to about 100 ml. Weak patients may add 5-15 red dates when decocting.
This formula works better than Tinglili Dazao Xie Fei Tang alone. After taking it, the patient's urination increases; some patients experience mild abdominal pain and diarrhea as side effects, which are normal pharmacologic reactions and need not cause alarm. However, pregnant women should use this formula with caution.
As a symptomatic formula, Xie Fei Tang may not cure the patient's disease, but it can ease suffering. It may be stopped once the clinical symptoms disappear. It only has an adjunctive therapeutic role for lung cancer and pulmonary tuberculosis and is not curative. Lung cancer patients taking this formula still need corresponding anti-cancer treatment, and tuberculosis patients still need anti-tuberculosis therapy.