泻肺降气、下痰。
辛甘微寒。长于降气、下痰止嗽。治肺气壅实。（喉中作水鸡声者、服之立愈。）胸膈逆
满。
肺实者宜。否则忌也。似牛膝。粗长坚直。脆而易断者。白前也。短小柔软。能弯不断者。
白薇也。（近道多有、形色颇同、以此别之。）去头须。甘草水浸一伏时。焙用。忌羊肉。
泻血热。
苦咸而寒。阳明冲任之药。利阴气。下水气。主中风身热支满。忽忽不知人。（阴虚火
旺、
则内热生风、火气焚灼、故身热支满、痰随火涌、故不知人。）血厥。（汗出过多、血少阳气
独上、气塞不行而厥、妇人尤多、此证宜白薇汤、白薇当归各一两、参五钱、甘草钱半、每
服五钱。）热淋温疟。寒热酸痛。（寒热作、则营气不能内荣、故酸痛。）妇人伤中淋露。（血
热、孙真人千金方、白薇散、治胎前产后遗尿不知时、白薇白芍等分、酒调服、丹溪曰∶此
即刘河间原病式所谓、热甚廷孔郁结、神无所依、不能收禁之意也、廷孔、女人溺孔也。）
产虚烦呕。（经疏云∶古方调经种子、往往用之、盖不孕缘于血热、而其源起于真阴不足、
阳胜而内热、故营血日枯也、益阴清热、则血自生旺而有子矣、须佐以归地芍药杜仲苁蓉等
药。）血热相宜。血虚则忌。似牛膝而短小柔软。去须。酒洗。恶大黄、大戟、山茱、姜枣。
（
冬各一两、百部二两、米饮服末一钱。）
[Qian Hu] (Cynanchum Stauntonii Rhizoma)
Drains the Lung, descends Qi, and reduces phlegm.
Pungent, sweet, slightly cold. It excels at descending Qi, reducing phlegm, and stopping cough. It treats excess stagnation of Lung Qi (those with a rattling sound in the throat like a water frog will be cured immediately upon taking it). It addresses rebellious fullness in the chest and diaphragm.
It is suitable for cases of Lung excess; otherwise, it is contraindicated. It resembles Niuxi (Achyranthis Bidentatae Radix). The coarse, long, firm, and straight pieces that are brittle and easily broken are Qian Hu. The short, small, soft, and flexible pieces that can bend without breaking are Baiwei [Rhizoma Cynanchi Atrati]. (In nearby regions, there are many such herbs with similar appearance and color; distinguish them by this method.) Remove the head and rootlets. Soak in licorice water for one shichen (two hours), then dry-roast before use. Avoid mutton.
[Bai Wei] (Rhizoma Cynanchi Atrati)
Drains blood heat.
Bitter, salty, cold. It is a herb for the Yangming, Chong, and Ren meridians. It benefits Yin Qi and promotes the downward movement of water qi. It primarily treats wind-stroke with body heat and distending fullness. Sudden loss of consciousness (Yin deficiency with hyperactive fire generates internal heat and wind; the burning fire qi causes body heat and distending fullness, and phlegm surges with the fire, leading to unconsciousness). Blood jue (excessive sweating leads to blood deficiency, allowing Yang Qi to rise alone; Qi obstruction prevents circulation, resulting in jue; this is particularly common in women; for this syndrome, Baiwei Tang is indicated: Baiwei and Danggui each 1 liang, Renshen 5 qian, Gancao 1.5 qian; take 5 qian per dose). Hot strangury and warm malaria. Alternating chills and fever with soreness and pain (when chills and fever occur, Ying Qi cannot nourish internally, hence soreness and pain). Women’s injury from middle jiao with dripping discharge (blood heat; Sun Simiao’s Qianjin Fang, Baiwei San, treats enuresis during pregnancy or postpartum where timing is unknown: Baiwei and Baishao in equal parts, taken with wine mixed. Danxi stated: This is exactly what Liu Hejian meant in Yuanbing Shi as "severe heat causing depression and knotting in the Ting Kong, with the spirit having no reliance, unable to retain control." Ting Kong refers to the female urethral opening). Postpartum deficiency with vexation and vomiting (Jingshu states: Ancient formulas for regulating menstruation and promoting conception often use this. Infertility due to blood heat originates from insufficient True Yin, with Yang prevailing and internal heat generated, causing Ying Blood to wither daily. Nourishing Yin and clearing heat allows Blood to generate and flourish, enabling conception; it must be assisted with herbs such as Danggui, Dihuang, Baishao, Duzhong, and Rongrong). It is suitable for blood heat; contraindicated for blood deficiency. It resembles Niuxi but is shorter, smaller, softer, and more flexible. Remove rootlets. Wash with wine. It is incompatible with Dahuang, Daji, Shanzhuyu, Jiang, and Zao. (Dong 1 liang each, Baibu 2 liang; take 1 qian of powder with rice water.)