体重泻火、气轻解肌。
甘辛而淡。体重而降。足阳明经（胃。）大寒之药，色白入肺，兼入三焦。（诸经气分。）
寒能
清热降火。辛能发汗解肌。甘能缓脾。生津止渴。治伤寒郁结无汗。阳明头痛。发热恶寒。
日晡潮热。阳狂壮热。（经云∶阳盛生外热。）小便赤浊。大渴引饮。中暑自汗。（能发汗、
又能止自汗。）舌焦（胎浓、无津。）牙痛。（阳明经热、为末、擦牙固齿。）又胃主肌肉。肺
主皮毛。（嘉言曰∶极清肺热。）为发斑疹之要品。（色赤如锦纹者为斑、隐隐见红点者为疹
、斑重而疹轻、率由胃热所致、然亦有阴阳二证、阳证宜用石膏、又有内伤阴证见斑疹者、
色微红而稀少、此胃气极虚、逼其无根之火游行于外、当补益气血、使中有主、则气不外游
、血不外散、若作热治、死生反掌。）少壮火热者。功效甚速。老弱虚寒者。祸不旋踵。（东
垣曰∶立夏前服白虎汤、令人小便不禁、降令太过也。）极能寒胃。胃弱血虚。及病邪未入
阳明者。切勿轻投。（成无己解大青龙汤曰∶风阳邪、伤卫、寒阴邪、伤营、营卫阴阳俱伤
、则非轻剂所能独散、必须重轻之剂同散之、乃得阴阳之邪俱去、营卫俱和、石膏乃重剂、
而又颛达肌表也、东垣曰∶石膏足阳明药、仲景用治伤寒阳明证、身热目痛、鼻干不得卧、
邪在阳明、肺受火制、故用辛寒以清肺气、所以有白虎之名、肺主西方也、按阳明主肌肉、
故身热、脉交 中、故目痛、脉起于鼻、循鼻外、金燥、故鼻干、胃不和则卧不安、故不得
卧、然亦有阳虚发热、及脾胃虚劳、伤寒阴盛格阳、内寒外热、类白虎汤证、误投之、不可
救也、按、阴盛格阳、阳盛格阴、二证至为难辨、盖阴盛极而格阳于外、外热而内寒、阳盛
极而格阴于外、外冷而内热、经所谓重阴必阳、重阳必阴、重寒则热、重热则寒是也、当于
小便分之、便清者、外虽燥热而中实寒、便赤者、外虽厥冷而内实热也、再看口中之燥润、
及舌胎之浅深、胎黄黑者为热、宜白虎汤、然亦有舌黑属寒者、舌无芒刺、口有津液也、急
宜温之、误投寒剂则死矣。）有软硬二种。莹白者良。研细。甘草水飞。近人因其寒。或用
火。则不甚伤胃。但用之鲜少。则难见功。（白虎汤以之为君、或自一两加至四两。）味淡
难出。（若入煎剂、须先煮数十沸。）鸡子为使。恶巴豆。畏铁。（今茶食内、俱加石膏粉、
取其价廉而且清凉可口也、害人不少。）
石膏体重能泻火，气轻能解肌。
味甘、辛而淡。质地重而性降。它是足阳明胃经的大寒之药，色白入肺，兼入三焦（诸经的气分）。
寒性能清热降火。辛性能发汗解肌。甘性能缓脾，生津止渴。治疗伤寒郁结无汗、阳明头痛、发热恶寒、日晡潮热、阳狂壮热（经文说：阳气盛则生外热）、小便赤浊、大渴引饮、中暑自汗（既能发汗，又能止自汗）、舌焦（舌苔厚腻、无津液）、牙痛（阳明经热，研末擦牙可固齿）。又因胃主肌肉，肺主皮毛（嘉言说：极清肺热），是治疗发斑疹的重要药物。（颜色红如锦纹的叫斑，隐隐见红点的叫疹，斑重疹轻，多由胃热所致；但也有阴阳两种证型，阳证宜用石膏；又有内伤阴证出现斑疹的，颜色微红且稀少，这是胃气极虚，逼迫无根之火游行于外，应当补益气血，使中有主宰，则气不外游，血不外散；若当作热证治疗，生死只在顷刻之间。）青壮年火热者，功效迅速；老弱虚寒者，灾祸随即而至（东垣说：立夏前服用白虎汤，令人小便不禁，是因为降令太过）。石膏极能寒胃，胃弱血虚，以及病邪未入阳明经者，切勿轻易投用（成无己解释大青龙汤说：风为阳邪，伤卫；寒为阴邪，伤营；营卫阴阳俱伤，则非轻剂所能单独解散，必须轻重之剂同用发散，才能使阴阳之邪俱去，营卫调和。石膏乃重剂，而又专达肌表。东垣说：石膏是足阳明经药，仲景用它治疗伤寒阳明证，身热目痛、鼻干不得卧，邪在阳明，肺受火制，故用辛寒以清肺气，所以有白虎之名，肺主西方。按阳明主肌肉，故身热；脉交中，故目痛；脉起于鼻，循鼻外，金燥，故鼻干；胃不和则卧不安，故不得卧。然而也有阳虚发热，及脾胃虚劳、伤寒阴盛格阳、内寒外热，类似白虎汤证的，误投此药，不可救也。按，阴盛格阳、阳盛格阴，二证最难辨别。盖阴盛极而格阳于外，外热而内寒；阳盛极而格阴于外，外冷而内热。经文所谓重阴必阳、重阳必阴、重寒则热、重热则寒就是这种情况。应当从小便分辨，小便清者，外虽燥热而中实寒；小便赤者，外虽厥冷而内实热。再看口中干燥湿润，及舌苔浅深，苔黄黑者为热，宜用白虎汤；然而也有舌黑属寒的，舌无芒刺，口有津液，急宜温之，误投寒剂则死矣。）石膏有软硬两种，莹白的为好。研细，用甘草水飞。近代人因其性寒，或用火煅，则不太伤胃，但用得很少，就难见效（白虎汤以它为君药，用量可从一两加至四两）。味道淡，难析出（若入煎剂，须先煮数十沸）。鸡蛋清为使药。恶巴豆，畏铁。（现在茶食内，都加石膏粉，取其价廉而且清凉可口，害人不少。）
Shigao (Gypsum Fibrosum) is heavy in weight to purge fire, and light in qi to release the muscle layer.
It is sweet, pungent, and bland. Its texture is heavy and its nature is descending. It is a major cold medicine for the Foot-Yangming Stomach Meridian (Stomach). Its white color enters the Lung, and it also enters the Sanjiao (Qi aspect of all meridians).
Its cold nature can clear heat and descend fire. Its pungency can induce sweating and release the muscle layer. Its sweetness can moderate the Spleen, generate fluids, and quench thirst. It treats Shanghan (Cold Damage) with stagnation and no sweating, Yangming headache, fever with aversion to cold, tidal fever at dusk, manic high fever (The Classic states: Excess Yang generates external heat), red and turbid urine, extreme thirst with excessive drinking, summerheat stroke with spontaneous sweating (it can both induce sweating and stop spontaneous sweating), scorched tongue (thick coating, lack of fluids), toothache (Yangming meridian heat; powdered and applied to teeth strengthens them). Furthermore, the Stomach governs muscles, and the Lung governs skin and hair (Jiayan stated: it extremely clears Lung heat). It is a key herb for treating macules and papules (Red like brocade patterns are called macules; faint red spots are called papules. Macules are severe and papules are mild, mostly caused by Stomach heat. However, there are also Yin and Yang syndromes. For Yang syndromes, Shigao is suitable. There are also internal injury Yin syndromes presenting with macules and papules, which are slightly red and sparse. This indicates extreme deficiency of Stomach Qi, forcing rootless fire to wander externally. One should tonify Qi and Blood to establish an internal master, so that Qi does not wander out and Blood does not scatter. If treated as heat, life and death depend on a moment.) For young and strong individuals with excess heat, its efficacy is rapid; for the old, weak, and deficient-cold, disaster follows immediately (Dongyuan stated: Taking Baihu Tang before Start of Summer causes incontinence due to excessive descending action). It extremely cools the Stomach. For those with weak Stomach and deficient Blood, or where pathogenic factors have not entered the Yangming meridian, do not administer lightly (Cheng Wuji explained Da Qinglong Tang: Wind is a Yang pathogen injuring Wei; Cold is a Yin pathogen Ying. When Ying and Wei, Yin and Yang are all injured, light agents alone cannot disperse them. Heavy and light agents must be used together to disperse, allowing Yin and Yang pathogens to depart and Ying and Wei to harmonize. Shigao is a heavy agent that specifically reaches the muscle surface. Dongyuan stated: Shigao is a Foot-Yangming herb. Zhongjing used it to treat Yangming syndrome of Shanghan, characterized by body heat, eye pain, nasal dryness, and inability to sleep. The pathogen is in Yangming, and the Lung is constrained by fire, hence pungent-cold is used to clear Lung heat, thus the name Baihu (White Tiger), as the Lung governs the West. According to analysis, Yangming governs muscles, hence body heat; the pulse intersects here, hence eye pain; the pulse starts at the nose and runs along the outside of the nose; Metal dryness causes nasal dryness; disharmony of the Stomach leads to restless sleep, hence inability to sleep. However, there are also Yang deficiency generating heat, Spleen-Stomach deficiency labor, and Shanghan with Yin excess repelling Yang, internal cold with external heat, resembling Baihu Tang syndrome. Misadministration is incurable. Note: Yin excess repelling Yang and Yang excess repelling Yin are difficult to distinguish. Extreme Yin excess repels Yang outward, causing external heat but internal cold; extreme Yang excess repels Yin outward, causing external cold but internal heat. The Classic states: Heavy Yin becomes Yang, heavy Yang becomes Yin, heavy cold becomes heat, heavy heat becomes cold. Differentiate by urine: clear urine indicates external dry-heat but internal true cold; red urine indicates external cold limbs but internal true heat. Observe mouth dryness/moisture and tongue coating depth: yellow-black coating indicates heat, suitable for Baihu Tang. However, black coating can indicate cold if there are no prickles and saliva is present; warm treatment is urgent, misusing cold agents leads to death.) There are two types: hard and soft. Those that are crystal white are superior. Grind finely and levigate with Licorice water. Modern people, fearing its coldness, sometimes calcine it with fire to reduce stomach damage, but it is rarely used effectively (In Baihu Tang, it is the sovereign herb, dosage ranging from 1 liang to 4 liang). Its taste is bland and extraction is difficult (If decocted, boil first for dozens of times). Egg white is the guiding substance. It is incompatible with Euphorbiae Pekinensis Radix (Badou), and fears iron. (Now, gypsum powder is added to tea snacks for its low cost and refreshing taste, harming many people.)