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Fresh Rehmannia Root

생지황 (生地黃) · Rehmannia glutinosa (Gaertn.) Libosch. ex Fisch. & C.A.Mey.
Heat-clearing, blood-cooling herb Cold Sweet (some sources: bitter) Heart, Small Intestine (Hand Taiyang and Shaoyin channels)
NatureCold
TasteSweet (some sources: bitter)
MeridiansHeart, Small Intestine (Hand Taiyang and Shaoyin channels)
Part usedFresh or sun-dried root
FamilyOrobanchaceae (formerly Scrophulariaceae)
CategoryHeat-clearing, blood-cooling herb
Find by concern: ThirstNosebleed

Overview

Raw rehmannia is the cold, blood-cooling twin of prepared rehmannia (sukjihwang), which is warm and tonifying. The Donguibogam spends effort on telling dried forms apart: steamed and dried it turns warm, while dried raw it stays more neutral. It also records an unusual float test — freshly dug roots dropped in water that float are "heaven" grade and useless, those half-floating are "human" grade and second best, and only those that sink, "earth" grade, are medicine — and warns never to let it touch copper or iron while harvesting.

In the Donguibogam

東醫
寶鑑
性寒, 味甘一云苦, 無毒. 解諸熱, 破血, 消瘀血, 通利月水. 主婦人崩中血不止, 及胎動下血, 幷衄血吐血.
Source: Donguibogam, Tangaek-pyeon (Herbology volume)
TranslationIts nature is cold, its taste sweet (some say bitter), and it is non-toxic. It resolves all kinds of heat, breaks and dissolves static blood, and frees menstruation. It mainly treats women’s flooding with unstoppable bleeding, bleeding with a disturbed fetus, and nosebleed and vomiting of blood.

Traditional uses recorded in the Donguibogam

  • Clears heat, cools the blood
  • Dissolves static blood
  • Generates blood
  • Frees menstruation

Traditional applications recorded in the classical text

  • Heat patterns with nosebleed or vomiting blood (classical use)
  • Heat-type thirst
  • Blood-heat patterns in women (classical use)

Traditional preparation

Root harvested in the 2nd or 8th lunar month and shade-dried; avoid copper and iron. Fat roots that sink in water are best. Wine-soaking sends the action upward and outward.

This describes traditional preparation recorded in the classics, not a recommendation for use today. DonguiHub does not provide dosage guidance — consult a qualified professional before using any herb.

Cautions

Caution: The Donguibogam, citing the classical text Uihak-jeongjeon, cautions that raw rehmannia can harm the stomach, so those with a weak stomach should not take it for long. Bleeding of any kind needs medical evaluation. Consult a professional.
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Frequently asked questions

What is the float test?

Freshly dug roots are dropped in water: floating roots (called "heaven") are unusable, half-floating roots ("human") are second best, and sinking roots ("earth") are the medicine — a classical grading of density and freshness.

How do raw and prepared rehmannia differ?

Raw is cold and cools the blood; prepared (sukjihwang) is warm and tonifies blood and marrow. Steamed-dried is warm; dried raw is more neutral.

Why avoid copper and iron?

The text lists it as a harvesting rule — roots must not touch copper or iron utensils — alongside several other herbs; it is a preparation rule, not a toxicity warning.

Sources