Medicinals
dà huáng / 大黄 / 大黃 / rhubarb;
Latin pharmacognostic name: Rhei Radix et Rhizoma
Alternate English names: Chinese rhubarb
Alternate Chinese names: 黄良 huáng liáng; 火参 huǒ shēn; 肤如 fū rú; 锦纹大黄 jǐn wén dà huáng; 峻 jùn; 川军 chuān jūn; 将军 jiāng jūn
Origin: Plant
Use: medicinal
Category: Draining-precipitant agents / Offensive precipitant agents
Properties: Bitter; cold.
Channel entry: spleen, stomach, and large intestine, liver, heart channels.
Indications:
- Drains and precipitates to attack accumulations:
Bound stool , stomach and intestinal accumulations and stagnation. - Drains fire and stanches bleeding: Frenetic movement of hot blood; fire-heat flaming upward.
- Clears heat and resolves toxin:
Heat toxin sore s; burns and scalds. - Additional uses: Dà huáng may be used for damp-heat patterns of jaundice and strangury (lìn) when combined with medicinals that clear and discharge damp-heat. For jaundice, use it with yīn chén (茵陈 Artemisiae Scopariae Herba, virgate wormwood;) and zhī zǐ (栀子 Gardeniae Fructus, gardenia [fruit];), as in the formula
yinchenhaotang . For damp-heat strangury, use it with mù tōng (木通 Akebiae Trifoliatae Caulis, trifoliate akebia), chē qián zǐ (车前子 Plantaginis Semen, plantago seed;), and zhī zǐ (栀子 Gardeniae Fructus, gardenia [fruit];), as in the formulabazhengsan . Dà huáng is decocted only for a short time when used to free the stool, but generally is decocted for a longer time when used for its blood-quickening action. Prolonged decoction reduces its precipitant effect.
Warning:
Dà huáng is very bitter and very cold. It easily damages stomach qì, so it should be used with care in weakness of the spleen and stomach. Because dà huáng is downbearing and sinking and also quickens the blood, it is contraindicated in pregnancy, during menstruation, and during breastfeeding (it can cause the infant to have diarrhea). Individual responses to the precipitating effect of dà huáng vary, so it should be noted that the dosage required for freeing the stool varies from patient to patient.
Product Description:
This rhizome is roughly ovate in shape and is a yellow brown in color with paler reticular markings. Rheum palmatum is 5–10 cm long and 4–8 in diameter and is heavy. Rheum officinale is larger, being anything up to 15 cm in diameter. It is lighter and spongier and bears pale reticular markings. It sometimes has a characteristic horse hoof shape (horse-hoof rhubarb, mǎ tí dà huáng). The decocting pieces are slices 2–4 mm thick, that are crude, cooked (steamed or stir-fried), or prepared in wine.
Quality:
Best are mottled or speckled yellowish-brown rhizomes that are firm, heavy, and oily in substance and that are bitter but not astringent to the taste.
Product Area:
Rheum palmatum: Sìchuān, Gānsū, Qīnghǎi, and Tibet. Rheum tanguticum: Qīnghai, Gānsū, and north-western Sìchuāng. These two types together are referred to as Northern rhubarb běi dà huáng, which includes the commercial products Xīníng rhubarb (xī ning dà huáng) and Quánshuǐ rhubarb (quán shuǐ dà huáng). R. officinale: Sìchuān. This is often commercially referred to as Sìchuān rhubarb (sì chuān dà huáng) or horse-hoof rhubarb (mǎ tí dà huáng).
Etymology:
Dà huáng 大黄, literally ""great yellow,"" reflects the size of the rhizome, its color, and possibly also its powerful action.