Xiebai San: A Famous Classical Formula for Treating Lung Disorders

Xiebai San (White-Dispersing Powder) is a classical famous formula from Key to Therapeutics of Children's Diseases (Xiao'er Yao Zheng Zhi Jue) by Qian Yi, a renowned physician of the Song Dynasty. The formula consists of 30g each of Cortex Lycii Radicis (Digu Pi) and Cortex Mori Albae Radicis (Sang Baipi), and 3g of Radix Glycyrrhizae Praeparata (Zhi Gancao). When used, these three herbs are ground into a coarse powder, mixed with a small handful of rice, decocted in two small bowls of water down to seven-tenths, and taken before meals.

In modern practice, the herbs are usually directly decocted into a herbal decoction and taken once each in the morning and evening before meals. In acute conditions, two doses may be taken per day, every two hours, and an additional dose may be taken at night. Here, one liang is converted to 30g in modern measure, and one qian is converted to 3 grams.

The indications for Xiebai San recorded in Key to Therapeutics of Children's Diseases are as follows: 1. It treats exuberant lung qi in children with shortness of breath and cough. 2. For strong fever with thirst for drinking, wheezing and oppression, Xiebai San governs. 3. For fullness in the chest with shortness of breath, urgent qi, wheezing and cough with upward counterflow, one should first disperse the lung, then release wind-cold. To disperse the lung, Xiebai San and Daqing Gao govern. 4. For deep red lips, treat by dispersing the lung. For deficiency heat, take a small amount of Xiebai San. 5. When lung disease appears in spring, the lung overacts on the liver; one should tonify the liver and kidney while treating the lung. A timid liver is the one that contracts the disease. To tonify the liver and kidney, use Di Huang Wan; to treat the lung, Xiebai San governs. 6. In those with exuberant lung, who cough and then wheeze, with facial swelling and a desire to drink water (and some who do not drink water but whose bodies become hot), purge them with Xiebai San.

Key to Therapeutics of Children's Diseases is a famous pediatrics text, yet Xiebai San is not only suitable for pediatric patients; it treats the condition of "exuberant lung" in both children and adults. "Xiebai" actually means "draining the lung." Ancient Chinese medicine held that the five zang organs correspond to the five colors, and the lung corresponds to the color white; therefore xiebai actually means draining the lung, and Xiebai San was originally also called Xiefei San (Lung-Draining Powder).

Judging from the five indications recorded by Qian Yi, Xiebai San mainly treats respiratory distress syndrome caused by infectious diseases in modern medicine (such as upper respiratory tract infection, bronchitis, tracheitis, pneumonia, asthma, and advanced lung cancer complicated by pneumonia). Since this disease mostly affects children, this formula is used especially frequently in pediatrics. The main symptoms are shortness of breath, cough and wheezing, hypoxemia, chest oppression, steaming heat of the skin, or dry mouth with excessive drinking.

Qian Yi had already noticed the problem of hypoxia in such patients. The "deep red lips" in indication No. 4 is what modern medicine calls cyanosis, caused by an abnormal content of reduced hemoglobin in the blood or an increase in hemoglobin derivatives. Hemoglobin is responsible for carrying oxygen to cells throughout the body; if the hemoglobin is abnormal, the blood oxygen content will be abnormal, and the skin and mucous membranes will take on a bluish-purple color. It is most apparent at the lips, nail beds, and cheekbones, because these areas are rich in capillaries, have thin skin, and have less pigmentation, making them easy to observe. Therefore Western medicine also gives auxiliary treatments such as oxygen inhalation to relieve symptoms in such patients.

Pulmonary infection mostly causes patients to have a dry mouth and to be very thirsty for water. The author has seen some lung cancer patients with this symptom; they breathe rapidly, have a dry mouth, and drink up to several liters of water daily. Treating such patients with Xiebai San has a certain symptomatic-relieving effect. Qian Yi also observed that some patients do not have a dry mouth but have a hot and dry body, both of which result from the body undergoing an inflammatory response.

Later generations of TCM mostly named the indication of Xiebai San as the syndrome of "latent fire in the lung" or "depressed heat in the lung," whose disease mechanism is the presence of evil fire-heat in the lung, with the treatment principle being to drain the depressed heat and latent fire from the lung. Traditional Chinese medicine holds that Cortex Lycii Radicis (Digu Pi) has the functions of clearing deficiency heat, purging lung fire, and quenching thirst and generating fluids; Cortex Mori Albae Radicis (Sang Baipi) drains the lung and calms wheezing, and promotes diuresis and reduces swelling; Radix Glycyrrhizae Praeparata (Zhi Gancao) both stops cough and mitigates the cold and harsh properties of Digu Pi and Sang Baipi. Therefore Qian Yi's Xiebai San uses few but refined herbs and is truly remarkable. Xiebai San has definite efficacy, and even today our medical community still uses it. Xiebai Tangjiang (Xiebai Syrup), a commonly used modern pediatric drug, was developed on the basis of both Xiebai San and Mahang Xinggan Shigan Tang (Ephedra, Apricot Kernel, Gypsum, and Licorice Decoction), and both TCM and Western pediatricians frequently use this medicine.

Qin Jingming, a famous physician of the Ming Dynasty, discovered in clinical practice that adding 9g of Scutellariae Radix (Huang Qin) to Xiebai San gave better results. So he composed a formula called "Huangqin Xiebai San": 30g each of Cortex Lycii Radicis (Digu Pi) and Cortex Mori Albae Radicis (Sang Baipi), 9g of Scutellariae Radix (Huang Qin), and 3g of Radix Glycyrrhizae Praeparata (Zhi Gancao), recorded in his book Syndrome, Cause, Pulse and Treatment (Zheng Yin Mai Zhi). Li Shizhen, the author of Compendium of Materia Medica (Bencao Gangmu), suffered from cough and wheezing when young, and his father cured him with the single herb Scutellariae Radix (Huang Qin). The single-herb remedy of using Huang Qin alone to treat lung disease is also called Yiwei Qingyin Yin (Single-Herb Metal-Clearing Drink—metal also corresponds to the lung in TCM). This shows that the Chinese herb Huang Qin has excellent effects in treating pulmonary infectious diseases, and Qin Jingming's addition of Huang Qin to Xiebai San is the icing on the cake.