Commentary from the Yīfāng jíjiě 《医方集解》 1689 CE
【Indications – 主治】
治自汗不止，氣虛表弱，易感風寒(1)。
1. 陽也者，衛外而為固也。陽虛不能衛外，故津液不固而易泄，且畏風也。此與傷風自汗不同，彼責之邪實，此責之表虛，故補散各異。
It treats incessant spontaneous sweating, qì deficiency with weakness of the exterior, easily susceptible to wind-cold [strike](1).
1. Regarding yáng, it defends the exterior and moreover it secures [the exterior]. If there is yáng deficiency then it is unable to defend the exterior, thus the jīnyè-fluids are not secured and easily leak, and in addition to fear of wind. This [pattern] and spontaneous sweating by wind damage at not identical, the latter is blamed on an excess evil, this is blamed on an exterior deficiency, that is difference between tonification and dissipation.
【Composition – 組成】
黃耆 炙 防風 一兩 白朮 炒二兩
為末，每服三錢。
Huáng qí (roasted), fángfēng each 1 liǎng
Báizhú (blast flied) 2 liǎng
【Formula Explanation – 方義】
此足太陽手足太陰藥也。黃耆補氣，專固肌表，故以為君，白朮益脾，脾主肌肉，故以為臣，防風去風，為風藥卒徒，而黃耆畏之，故以為使，以其益衛固表，故曰玉屏風。
These are foot tàiyáng, hand and foot tàiyīn herbs. Huángqí tonifies qì, specialises in securing the fleshy exterior, therefore it is the monarch herb. Báizhú governs boosting the spleen, the spleen governs the flesh, therefore it is the minister herb. Fángfēng eliminates wind, using a wind medicinal then [the wind] will suddenly leave, more over huángqí wèi zhī, therefore it is the courier herb. Because it supplements the wèi-defensive and secures the exterior, thus it is called Yù Píng Fēng (Jade Screen [Protecting from] Wind).
【Discussion of the formula – 方論】
李東垣曰：黃耆得防風而功益大，取其相畏而相使也。
Lǐ Dōngyuán said “Huángqí together with fángfēng increases the function greatly, this is the point of [using the herbal relationships of] fear and empowering.
《証治準繩》曰：卒中偏枯之證，未有不因真氣不週而病者，故黃耆為必用之君藥，防風為必用之臣藥，黃耆助真氣者也。防風載黃耆助真氣以周于身者也。亦有治風之功焉，許胤宗治王太后中風口噤，煎二藥薰之而愈，況服之乎？
The Criterion for Patterns and Treatments states: the pattern stroke and hemiplegia, has never been not caused by zhēn-true qì circulating which leads to this disease. Therefore huángqí must be the monarch herb, and fángfēng must be the minister herb, because huángqí assists the zhēn-true qì. Fángfēng enables huángqí to assist the zhēn-true qì around the whole body. It also has the treats wind with excellence, Xǔ Yìnzōng (of the Tang Dynasty) treated the Emperor’s mother for wind-strike with clenched jaw, [after] cooking the two herbs and then she]recovered. What could be comparable to taking this formula?
【Additional Formulas – 附方】
前藥等分煎，名黃耆湯，潔古用代桂枝湯，治春夏發熱有汗，脈微弱，惡風寒者，惡風甚，加桂枝。
Using the three herbs in equal parts and fried, this is named Huángqí Tāng, Jiégǔ uses it as a substitute for Guìzhī Tāng. It treats spring-summer fevers with sweating, faint and weak pulse, aversion to wind and cold, if the aversion to wind is severe then add guìzhī.
又用川芎、蒼朮、羌活、等分，名川芎湯，以代麻黃湯，治秋冬發熱無汗惡風寒者，惡寒甚加麻黃。
Another use chuānxiōng, cāngzhú, and qiānghuó, in equal parts, and this formula is named Chuānxiōng Tāng, it can be substituted for Máhuáng Tāngit. It treats autumn and winter fevers, absence of sweating and aversion to wind-cold, if the aversion to wind is severe add máhuáng.