气寒，味苦，阴中之阳。甘，微苦，味浓气薄，阴中阳也。无毒。
入手足少阴
《象》云∶酒洒，蒸如乌金，假酒力则微温，大补，血衰者须用之。善黑须发。忌萝卜
。
《珍》云∶若治外、治上，酒制。
《心》云∶生则性大寒而凉血，熟则性寒而消肾。
《本草》云∶主折跌、绝筋、伤中，逐血痹，填骨髓，长肌肉。作汤，除寒热积聚，除
痹；主男子五劳七伤，女子伤中、胞漏下血；破恶血，溺血。利大小肠，去胃中宿食，饱力
断绝，补五脏内伤不足；通血脉，益气力，利耳目。生者，尤良。得清酒、麦门冬，尤良。
恶贝母。畏芜荑。
东垣云∶生地黄，治手足心热，及心热。入手足少阴、手足厥阴，能益肾水而治血，脉
洪实者，宜此；若脉虚，则
宜熟地黄。地黄假火力蒸九数，故能补肾中元气。仲景制八味丸，
以熟地黄为诸药之首，天一所生之源也。汤液四物以治藏血之脏，亦以干熟地黄为君者，癸
乙同归一治也。蒸捣不可犯铁，若犯铁，令人消肾。
陈藏器云∶蒸干即温补，生干即平宣。
《机要》云∶熟地黄，脐下发痛者，肾经也，非地黄不能除。补肾益阴之剂，二宜丸加
当归为补髓。
气寒，味苦，阴中之阳。甘、苦，大寒。无毒。
入手太阳经、少阴经之剂。
《象》云∶凉血补血，补肾水真阴不足。此药大寒，宜斟酌用之，恐损胃气。
《珍》云∶生血凉血。
《本草》云∶主妇人崩中血不止，及产后血上薄心闷绝，伤身胎动下血，胎不落，堕坠
折，瘀血留血，衄鼻吐血，皆捣饮之。
《液》云∶手少阴，又为手太阳之剂，故钱氏泻丙与木通同用，以导赤也。诸经之血热
与他药相随，亦能治之，溺血便血亦治之，入四散例。
《心》云∶苦甘，阴中微阳，酒浸上行、外行。生血，凉血去热。恶贝母，畏芜荑。
(Sheng Dihuang / Raw Rehmanniae Radix) Its qi is cold, its taste is bitter, belonging to yin containing yang. It is sweet, slightly bitter, with a dense flavor and thin aroma, also representing yang within yin. It is non-toxic.
It enters the Hand Shaoyin (Heart) and Foot Shaoyin (Kidney) meridians.
Xiang states: Sprinkled with wine and steamed until black like obsidian gold, borrowing the warming power of wine makes it slightly warm. It greatly tonifies blood deficiency; those with blood deficiency must use it. It excels at darkening beard and hair. Avoid radish.
Zhen states: If treating exterior or upper body conditions, process with wine.
Xin states: When raw, its nature is greatly cold and cools blood; when cooked, its nature is cold and clears kidney fire (Xiao Shen).
Bencao states: It mainly treats fractures, severed tendons, and internal injuries; expels blood bi; fills the marrow; promotes muscle growth. Decocted, it removes cold-heat accumulations and bi syndrome; treats five labors and seven injuries in men, and middle injury, uterine leakage, and bleeding in women; breaks down evil blood and treats hematuria. It benefits the large and small intestines, removes retained food in the stomach, restores digestive strength, tonifies deficiencies of the five zang organs internally; unifies blood vessels, boosts qi and strength, benefits ears and eyes. The raw form is especially good. Combined with clear wine and Ophiopogonis Radix (Maidong), it is even better. It is incompatible with Fritillariae Bulbus (Beimu). It fears Elaeagnus Fructus (Wuyi).
Li Dongyuan says: Sheng Dihuang treats heat in the palms and soles, as well as heart heat. It enters the Hand Shaoyin, Foot Shaoyin, Hand Jueyin, and Foot Jueyin meridians. It can benefit kidney water and treat blood disorders. For patients with a surging, full, and solid pulse, this herb is suitable; if the pulse is deficient, Shu Dihuang (Cooked Rehmanniae Radix) is suitable. By steaming Dihuang nine times using fire power, it can tonify the primordial qi in the kidneys. Zhang Zhongjing formulated Ba Wei Wan (Eight-Ingredient Pill), using Shu Dihuang as the chief ingredient among all herbs, as it is the source generated by Heaven One. Tang Ye Si Wu Tang (Four Substances Decoction) treats the zang organs that store blood, also using dried Shu Dihuang as the sovereign herb, because Gui Water (Kidney Yin) and Yi Wood (Liver Blood) return to one treatment method. Steaming and pounding must not involve iron; if iron is touched, it causes Xiao Shen (kidney depletion).
Chen Cangqi says: When steamed and dried, it becomes warm and tonifying; when dried raw, it remains neutral and dispersing.
Jiyao states: For Shu Dihuang, pain below the umbilicus belongs to the Kidney meridian; only Dihuang can eliminate it. In formulas for tonifying the kidney and benefiting yin, adding Danggui (Angelicae Sinensis Radix) to Er Yi Wan tonifies the marrow.
(Raw Rehmanniae Radix) Its qi is cold, its taste is bitter, belonging to yin containing yang. Its taste is sweet and bitter, greatly cold. It is non-toxic.
It is used in formulas entering the Hand Taiyang (Small Intestine) and Hand Shaoyin (Heart) meridians.
Xiang states: It cools blood and tonifies blood, tonifying the true yin deficiency of kidney water. This herb is greatly cold; use it with discretion, as it may damage stomach qi.
Zhen states: Generates blood and cools blood.
Bencao states: It mainly treats menorrhagia and continuous postpartum bleeding, blood rushing to the heart causing suffocation after childbirth, damaged body, fetal movement with lower bleeding, retained placenta, falls and fractures, retained stasis, epistaxis, and hematemesis; all should be crushed and taken as a drink.
Ye states: Entering the Hand Shaoyin, and also serving as an agent for the Hand Taiyang, Qian Shi (Qian Yi) uses it together with Tongcao (Akebia Caulis) to clear Bing (Heart Fire) and guide redness (Dao Chi). It can treat blood heat in various meridians when combined with other herbs; it also treats hematuria and hematochezia, falling into the category of Si San (Four Scattering) formulas.
Xin states: Bitter and sweet, slightly yang within yin. Soaked in wine, its action moves upward and outward. It generates blood, cools blood, and removes heat. It is incompatible with Fritillariae Bulbus (Beimu). It fears Elaeagnus Fructus (Wuyi).