生洲渚沙碛上。秋后采根。粗长坚直。色白微黄。折之易断者。为白前。细短柔韧。色
黄微白。折之不断者。白薇也。味甘辛。气微温微寒。阳中之阴。降也。手太阴肺家治咳要
药。更入手阳明足阳明经。主胸胁逆气。咳嗽上气。呼吸欲绝。（别录） 又治肺气烦闷。
贲豚肾气。（日华子） 长于降气。肺气壅实而有痰者宜之。若虚而长哽气者。不可用。（濒
湖）凡咳嗽而喉中作声者。一味白前煎服妙。久咳上气。体肿气短。昼夜倚壁不得卧。常作
水鸡声者。深师白前汤。白前紫菀半夏大戟各三两。水一斗。渍一宿。煮取三升。分数十服。
间
〔论〕白前主治。首言胸胁逆气。夫胸中固肺所治。而胁则阴阳升降之道路也。又主咳
嗽上气。呼吸欲绝。夫呼吸即升降之气。阴阳之分而合者。肺为气主。贯心脉而行呼吸。呼
吸欲绝。是有升无降。或阴或阳。皆能病之。如下之真阴不足。不能召上之阳。即无以吸上
而气不降。（此为气不归元）上之真阳不足。不能生下之阴。即无以归下而气亦不降。（此中
气大虚而失守。须大剂参 而愈。）二者皆虚证。非白前可治也。惟是后天气血之病。偏胜
所成。上实而下即虚。（如痰热上壅。阳愈失阴而亢。气固不降。）下实而上即虚。（如贲豚
肾气。阴愈逼阳而僭。其气亦不降。）随其所主之味。而以兹味为前导。庶乎近之。（此味三
阴并施。脏腑咸入。其功靡不前至。故名。）
缪氏云。走散下气。性无补益。凡咳逆气上。不由于邪客壅实者。禁用。
〔修治〕 甘草水浸。去头须。焙干用。
Grows on sandbars and sandy beaches. The roots are harvested after autumn. Those that are thick, long, hard, and straight, with a white color slightly tinged with yellow, and break easily when snapped, are named Baiqian (Cynanchum glaucescens, White Cynanchum Root). Those that are thin, short, soft, and flexible, with a yellow color slightly tinged with white, and do not break easily when snapped, are Baiwei (Cynanchum stauntonii, Cynanchum Root). It tastes sweet and pungent, has a slightly warm or slightly cold nature, belongs to Yin within Yang, and has a descending action. It is an essential herb for the Hand-Taiyin Lung Meridian in treating coughs, and also enters the Hand-Yangming Large Intestine Meridian and Foot-Yangming Stomach Meridian. It primarily treats rebellious Qi in the chest and hypochondrium, coughing with upward rushing of Qi, and breathing so rapid as to be nearly interrupted. (From *Bielu*) It also treats irritability due to Lung Qi stagnation and Ben Tun Shen Qi (a syndrome characterized by the sensation of Qi rushing from the lower abdomen up to the heart and chest) (From *Rihua Zi*). This herb excels at descending Qi and is suitable for cases of Lung Qi obstruction with excess and phlegm. However, it should not be used in deficiency cases presenting with chronic belching. (From Li Shizhen) For any cough accompanied by sounds in the throat, decocting and taking a single dose of Baiqian yields excellent results. For chronic cough with upward rushing of Qi, bodily swelling, shortness of breath, inability to lie flat day or night but only leaning against walls, and frequent wheezing sounds resembling those of a water frog, use Shenshi Baiqian Tang. The formula contains Baiqian, Ziwan (Asteris Radix), Banxia (Pinelliae Rhizoma Preparatum), and Daji (Euphorbiae Pekinensis Radix), each three liang. Use one dou of water, soak overnight, boil to obtain three sheng of liquid, and divide into dozens of doses for administration.
[Discussion] The primary indications of Baiqian first mention rebellious Qi in the chest and hypochondrium. The chest is indeed governed by the Lung, while the hypochondrium serves as the pathway for the ascending and descending of Yin and Yang. It also treats coughing with upward rushing of Qi and breathing so rapid as to be nearly interrupted. Respiration is the Qi of ascending and descending, representing the separation and union of Yin and Yang. The Lung is the master of Qi, penetrating the Heart vessels and governing respiration. Breathing so rapid as to be nearly interrupted indicates rising without descending; whether due to Yin or Yang pathology, both can cause this condition. For instance, if the True Yin in the lower jiao is insufficient and cannot attract the Yang Qi from above, there will be no inhalation upwards, leading to non-descending Qi. (This is referred to as "Qi failing to return to its origin.") If the True Yang in the upper jiao is insufficient and cannot generate the Yin from below, the Qi cannot descend and store itself, leading to non-descending Qi. (This is severe deficiency of Middle Qi with loss of control, requiring large doses of Ginseng herbs to cure.) Both scenarios are deficiency syndromes and are not treatable by Baiqian. Only pathological conditions of acquired Post-Heaven Qi and Blood, resulting from excessive dominance, fit this indication: Upper Excess leads to Lower Deficiency (e.g., Phlegm-Heat obstructing the upper, causing Yang to become hyperactive due to lack of Yin restraint, thus Qi fails to descend); Lower Excess leads to Upper Deficiency (e.g., Ben Tun Shen Qi, where Yin forces Yang to rebel, causing Qi to fail to descend). Guided by the specific flavors and using this herb as a pioneer, one approaches the correct treatment principle. (This herb acts on all three Yin meridians and enters all Zang-Fu organs; its efficacy reaches everywhere, hence the name "Qian" meaning "before" or "pioneer".)
Miao Xi Yong stated: It disperses and descends Qi, possessing no tonifying properties. It is strictly contraindicated for coughing and rebellious Qi that does not arise from pathogenic invasion and excess obstruction.
[Processing] Soak in Licorice Water, remove the root heads and whiskers, then dry by baking before use.