【气味】
苦寒无毒。沉而降。阴也。又云阴中微阳。入足阳明手太阴气分。
【主治】
泻肾经之火。作利小便之佐使。疗利疾重下痛。祛消渴及久疟。烦热。凡伤寒烦燥
不得眠者。烦出于肺。燥出于肾。白虎汤君以石膏。佐以知母之苦寒。谓非大凉不能清肾之
源也。然必缓之以甘草粳米之甘。使不速下。用者酌之。又热在下焦血分。烦扰懊 。小便
闭塞而不渴。乃真水不足。膀胱干涸。无阴而阳无以化。法当补肾与膀胱。使阴气行而阳气
化。小便自通。知母苦寒。能直达肾与膀胱。清邪热以领正气。泻即补也。又热在上焦气分
。肺中伏热不能生水。膀胱绝其化源。其病小便闭塞而渴。知母气薄味薄。泻肺火而清肺金
。亦泻即是补也。后人不谙泻补之义。竟以知母黄柏为滋阴补肾之剂。祸及脾胃。中气致伤
。则惑之甚也。用者慎之。
（即生地之干也）
【气味】
甘寒无毒。沉而降。阴也。入手足少阴厥阴及手太阳之经。
【主治】
伤中。逐血。填骨髓。长肌肉。通血脉。益气力。除皮肤燥。去诸湿热。疗折跌绝
筋。生地黄气味主治及所入经络。即与干地黄同。大约阴微阳盛。相火炽强。来乘阴位。口
渐煎熬。为虚火之症。宜用此以滋阴退阳。故钱氏泻丙火与木通同用以导赤也。如血虚劳热
。产后虚热。老人中虚燥热者。若与生干地黄。当虑太寒。
【气味】
味苦，性寒，无毒。药性沉降，属于阴。又有说法认为其属“阴中微阳”。归入足阳明胃经和手太阴肺经的气分。
【主治】
清泻肾经的实火。作为利尿药物的辅助引导药。治疗痢疾且伴有严重里急后重疼痛的情况。祛除消渴病（糖尿病类症状）及久治不愈的疟疾、烦热。凡是伤寒病中出现烦躁、无法入睡的症状，这种“烦”源于肺，“燥”源于肾。在白虎汤（Baihu Tang, White Tiger Decoction）中，以石膏（Shigao, Gypsum Fibrosum）为君药，佐以知母的苦寒之性，是因为若非大凉之品，不能清泻肾之源头的火热。但是，必须用甘草（Gancao, Glycyrrhizae Radix et Rhizoma）和粳米（Jingmi, Oryzae Fructus Googongvar.）的甘缓之性来制约它，使其药力不至于过快下行。使用者需斟酌掌握。另外，若热邪在下焦血分，出现心烦意乱、懊恼不安，小便闭塞但口不渴，这是真阴不足，导致膀胱干涸，无阴则阳气无法化生。治法应当补肾与膀胱，使阴气运行而阳气得以化生，小便自然通畅。知母味苦性寒，能直达肾与膀胱，清泻邪热以引领正气，这里的“泻”实际上也是一种“补”。再者，若热邪在上焦气分，肺中伏热不能生水，导致膀胱失去化源，病症表现为小便闭塞且口渴。知母气薄味薄，能清泻肺火并清润肺金，这也是“泻即是补”的道理。后世之人不明白“泻”与“补”的真义，竟然将知母和黄柏（Huangbai, Phellodendri Cortex）当作滋阴补肾的药剂，这会导致损害脾胃，损伤中气，这是极大的谬误。使用者务必谨慎。
（即生地黄干燥后的形态）
【气味】
味甘，性寒，无毒。药性沉降，属于阴。归入手少阴心经、足少阴肾经、厥阴肝经及手太阳小肠经。
【主治】
治疗内伤虚损。驱逐瘀血。填补骨髓。促进肌肉生长。疏通血脉。益气力。消除皮肤干燥。去除各种湿热之邪。治疗跌打骨折导致的筋脉断裂。生地黄的气味、主治功效及所入经络，与干地黄相同。大致而言，若是阴液微弱而阳气偏盛，相火炽盛强横，侵犯阴位，逐渐煎熬阴液，形成虚火病症，适宜使用此药以滋阴退阳。因此，钱乙（Qian Yi, Song Dynasty Physician）在泻丙火（清心火）时，将其与木通（Mutong, Akebiae Caulis）同用以导赤散（Daochi San）。如果是血虚引起的劳热，产后虚热，或老人中气虚弱兼有燥热的情况，如果使用生地黄和干地黄，应当顾虑其过于寒凉。
[Flavor and Nature]
Bitter, cold, non-toxic. The medicinal property is sinking and descending, belonging to Yin. It is also said to be "Yin with slight Yang." It enters the Qi level of the Foot-Yangming Stomach Meridian and the Hand-Taiyin Lung Meridian.
[Indications]
Clears and drains fire from the Kidney Meridian. Acts as an assistant and guide for promoting urination. Treats dysentery accompanied by severe tenesmus and pain. Dispels polydipsia (Xiao Ke) and chronic malaria, along with vexatious heat. In cases where Shanghan (Cold Damage) presents with vexation and insomnia, "vexation" originates from the Lung, while "dryness" originates from the Kidney. In Baihu Tang (White Tiger Decoction), Shigao (Gypsum Fibrosum) serves as the sovereign drug, assisted by the bitter-cold nature of Zhi Mu (Anemarrhenae Rhizoma). This is because only a substance of great coolness can clear the source of heat in the Kidney. However, its action must be moderated by the sweetness of Gancao (Glycyrrhizae Radix et Rhizoma) and Jingmi (Oryzae Fructus Googongvar.) to prevent it from acting too rapidly downward. Practitioners should exercise discretion. Furthermore, if heat resides in the Blood level of the Lower Jiao, causing mental restlessness and discomfort, urinary obstruction without thirst, this indicates a deficiency of True Yin, leading to dryness of the Bladder. Without Yin, Yang cannot transform. The treatment method should tonify the Kidney and Bladder, allowing Yin Qi to circulate so that Yang Qi can transform, resulting in free urination. Zhi Mu, being bitter and cold, can reach the Kidney and Bladder directly, clearing pathogenic heat to lead healthy Qi; here, "draining" is essentially "tonifying." Additionally, if heat resides in the Qi level of the Upper Jiao, with latent heat in the Lung preventing the generation of fluids, thereby cutting off the source of transformation for the Bladder, the disease manifests as urinary obstruction accompanied by thirst. Zhi Mu has thin Qi and thin Flavor; it drains Lung Fire and clears Lung Metal. This is also a case where "draining is tonifying." Later generations, unfamiliar with the meaning of draining and tonifying, mistakenly used Zhi Mu together with Huangbai (Phellodendri Cortex) as a formula for nourishing Yin and tonifying the Kidney. This harms the Spleen and Stomach and injures Middle Qi, which is a profound confusion. Practitioners must be cautious.
(Refers to the dried form of Sheng Di Huang)
[Flavor and Nature]
Sweet, cold, non-toxic. The medicinal property is sinking and descending, belonging to Yin. It enters the Hand-Shaoyin Heart Meridian, Foot-Shaoyin Kidney Meridian, Jueyin Liver Meridian, and Hand-Taiyin Small Intestine Meridian.
[Indications]
Treats internal injury and deficiency. Expels blood stasis. Fills the bone marrow. Promotes muscle growth. Unblocks blood vessels. Augments Qi and strength. Eliminates skin dryness. Removes various damp-heat pathogens. Treats fractures and dislocations causing tendon rupture. The flavor, nature, indications, and meridians entered by Sheng Di Huang (Rehmanniae Radix) are the same as those of Gan Di Huang (Rehmanniae Radix Preparata). Generally speaking, when Yin is weak and Yang is excessive, with vigorous Minister Fire invading the Yin position and gradually consuming Yin fluids, resulting in symptoms of deficient fire, this herb should be used to nourish Yin and subdue Yang. Therefore, Qian Yi (Song Dynasty Physician) combined it with Mutong (Akebiae Caulis) to clear Bing Fire (Heart Fire) and guide redness (Daochi San). In cases of labor fever due to Blood deficiency, postpartum deficiency fever, or middle deficiency with dry-heat in the elderly, one must consider the potential harm of excessive coldness if using Sheng Di Huang or Gan Di Huang.