气平。味辛。有毒。主伤寒寒热心下坚。胸胀咳逆头眩。咽喉肿痛。肠鸣。下气。
止汗。（汤浸去涎净姜汁拌焙）
半夏气平。禀天秋燥之金气。入手太阴肺经。味辛有毒。得地西方酷烈之金味。入足阳
明胃
经、手阳明大肠经。气平味升。阳也。主伤寒寒热心下坚者。心下脾肺之区。太阴经行之地
也。病伤寒寒热而心下坚硬。湿痰在太阴也。半夏辛平。消痰去湿。所以主之。胸者肺之部
也。胀者气逆也。半夏辛平。辛则能开。平则能降。所以主之也。咳逆头眩者。痰在肺。则
气不下降。气逆而头眩晕也。东垣曰。太阴头痛。必有痰也。半夏辛平消痰。所以主之。咽
喉太阴经行之地。火结则肿痛。其主之者。辛能散结。平可下气。气下则火降也。肠鸣者。
大肠受湿。则肠中切痛。而鸣濯濯也。辛平燥湿。故主肠鸣。下气者。半夏入肺。肺平则气
下也。阳明之气本下行。上逆则汗自出矣。平能降气。所以止汗也。
制 方:
半夏同黄连、栝蒌实。名小陷胸汤。治心下坚。同甘草、防风、生姜。治痰厥中风。同
神曲
、南星、白术、枳实、姜汁。治风痰湿痰。同甘草。治风痰喘急。同黄芩、姜汁。治上焦热
痰。同白芍、甘草、黄芩。治身热吐泻。同瓜仁。治肺热咳。同陈皮。治痰饮。同白茯。治
水饮。同人参。治反胃。同白茯、甘草丸。名消暑丸。治伏暑。同人参、白茯、白术、甘草
、陈皮。名六君子汤。治脾湿生痰。不思饮食。
Nature is neutral. Flavor is acrid. It is toxic. It primarily treats chills and fever associated with Shanghan (Cold Damage), hardness in the epigastrium, chest distension, cough with counterflow qi, dizziness, sore throat and swelling, and borborygmus. It directs qi downward and stops sweating. (Preparation: Soak in decoction, remove saliva/mucus, wash clean, mix with ginger juice, and bake.)
Banxia (Pinelliae Rhizoma) has a neutral nature, inheriting the dry metal energy of autumn, entering the Hand-Taiyin Lung Meridian. Its flavor is acrid and it is toxic, acquiring the intense metal flavor of the west, entering the Foot-Yangming Stomach Meridian and the Hand-Yangming Large Intestine Meridian. Its nature is neutral and its flavor ascends; it belongs to Yang. It treats chills and fever with hardness in the epigastrium because the epigastrium is the region of the Spleen and Lung, where the Taiyin Meridian travels. When one contracts Shanghan resulting in chills, fever, and hardness in the epigastrium, it is due to damp-phlegm stagnating in the Taiyin. Banxia is acrid and neutral, eliminating phlegm and drying dampness, thus treating this condition. The chest is the domain of the Lung; distension indicates counterflow of qi. Banxia is acrid and neutral; acridness can disperse, and neutrality can descend, thus treating this condition. Cough with counterflow qi and dizziness occur because phlegm in the Lung prevents qi from descending; the counterflowing qi causes dizziness. Li Dongyuan stated: "Taiyin headache must involve phlegm." Banxia is acrid and neutral, eliminating phlegm, thus treating this condition. The throat is the pathway of the Taiyin Meridian; fire accumulation causes swelling and pain. Banxia treats this because acridness can dissipate nodules, and neutrality can direct qi downward; when qi descends, fire also descends. Borborygmus occurs because the Large Intestine is affected by dampness, causing cutting pain in the intestines and gurgling sounds. Banxia is acrid and neutral, drying dampness, thus treating borborygmus. "Directing qi downward" refers to Banxia entering the Lung meridian; when Lung qi is balanced, qi descends. The Qi of the Yangming Meridian naturally flows downward; if it counterflows upward, spontaneous sweating occurs. Banxia's neutrality can descend qi, thus stopping sweating.
Formulation Methods:
Banxia combined with Huanglian (Coptidis Rhizoma) and Gualou Shi (Trichosanthis Fructus), named Xiaoxianxiong Tang (Minor Intrapectoral Decoction), treats hardness in the epigastrium. Combined with Gancao (Glycyrrhizae Radix et Rhizoma), Fangfeng (Saposhnikoviae Radix), and Shengjiang (Zingiberis Rhizoma Recens), it treats stroke due to phlegm-jue. Combined with Shenqu (Massa Medicata Fermentata), Nanting (Arisaracae Rhizoma), Baizhu (Atractylodis Macrocephalae Rhizoma), Zhishi (Aurantii Fructus Immaturus), and Jiangzhi (Zingiberis Rhizoma Recens Juice), it treats wind-phlegm and damp-phlegm. Combined with Gancao, it treats wheezing and urgency due to wind-phlegm. Combined with Huangqin (Scutellariae Radix) and Jiangzhi, it treats upper jiao heat-phlegm. Combined with Baishao (Paeoniae Radix Alba), Gancao, and Huangqin, it treats body heat with vomiting and diarrhea. Combined with Gua Ren (Benincasae Semen), it treats lung-heat cough. Combined with Chenpi (Citri Reticulatae Pericarpium), it treats phlegm-fluid retention. Combined with Fuling (Poria), it treats water-fluid retention. Combined with Renshen (Ginseng Radix et Rhizoma), it treats regurgitation. Combined with Fuling and Gancao as pills, named Xiaoshu Wan (Summerheat-Dispelling Pill), treats latent summerheat. Combined with Renshen, Fuling, Baizhu, Gancao, and Chenpi, named Liujunzi Tang (Six Gentlemen Decoction), treats phlegm generated by spleen-dampness and loss of appetite.