Detailed Explanation of the Latest Processing Methods and Technical Key Points for Rehmannia

Rehmannia is one of the “four major Huai medicines”, with a long historical record. It is cool in nature and sweet-bitter in taste, with effects of nourishing yin and tonifying the kidney, nourishing and replenishing blood, and cooling blood. The effects differ depending on the processing method. Let us take a look at the processing methods for Rehmannia below!

Fresh Rehmannia

[Processing] When needed, take the fresh raw herb, remove impurities, wash clean, and cut into sections.

[Characteristics] Spindle-shaped or strip-shaped, 8-24 cm long, 2-9 cm in diameter. The outer bark is thin, the surface is pale reddish-yellow, with curved longitudinal wrinkles, bud scars, transversely elongated lenticels, and irregular scars. Fleshy, easily broken. The cortex in cross-section is pale yellowish-white, with visible orange-red oil dots; the xylem is yellowish-white, with vessels arranged radially. Slight odor, slightly sweet and slightly bitter taste.

[Nature and Taste] Sweet, bitter, cold.

[Meridian Tropism] Heart, liver, and kidney meridians.

[Effects] Clears heat and promotes fluid production, cools blood, and stops bleeding. Used for damage to yin from febrile disease, crimson tongue with restlessness and thirst, macules and papules, hematemesis, epistaxis, and sore throat.

Raw Rehmannia

[Processing] Take the raw herb, remove impurities, wash clean, moisten until soft, cut into thick slices, and dry.

[Characteristics] Mostly flat-round thick slices, 2-7 cm in diameter. The surface is grayish-brown to blackish-brown, with irregular wrinkles. The cut surface is brownish-black or brownish-gray, slightly glossy, and sticky. The texture is relatively soft and tough. Slight odor, slightly sweet taste.

[Nature and Taste] Sweet, cold.

[Meridian Tropism] Heart, liver, and kidney meridians.

[Effects] Clears heat and cools blood, nourishes yin, and promotes fluid production. Used for crimson tongue with restlessness and thirst in febrile disease, yin deficiency with internal heat, steaming bone and consumptive fever, internal heat with wasting-thirst, hematemesis, epistaxis, macules and papules. Raw Rehmannia charcoal nourishes yin and stops bleeding. Used for various bleeding disorders.

Raw Rehmannia Charcoal

[Processing] Take raw Rehmannia, stir-fry until thick smoke rises, the surface swells and turns charcoal black, and the interior is brownish-brown; then lightly spray with water, extinguish all sparks, take out, and air-dry.

[Characteristics] The surface is scorched black, and the interior is brownish-brown. The texture is loose and brittle. Slight scorched odor, slightly bitter taste.

[Nature and Taste] Sweet, bitter, slightly astringent, cool.

[Meridian Tropism] Heart, liver, and kidney meridians.

[Effects] Clears heat, promotes fluid production, nourishes yin, and nourishes blood. Used for warm febrile disease with heat entering the nutrient and blood levels, with symptoms such as feverish body and dry mouth, crimson or red tongue, etc.

Prepared Rehmannia

[Processing] Take raw Rehmannia moistened with water until soft, place in a suitable container, steam for about 6-8 hours, braise overnight, until it is moist and black inside and out, then take out, air-dry until 70-80% dry, and dry.

[Characteristics] The whole is moist and black, with luster. The texture is soft and somewhat resilient, not easily broken, and strongly sticky. Sweet taste.

[Nature and Taste] Sweet, slightly warm.

[Meridian Tropism] Liver and kidney meridians.

[Effects] Nourishes yin and tonifies blood, benefits essence and fills marrow. Used for yin deficiency of the liver and kidney, soreness and weakness of the waist and knees, steaming bone and tidal fever, night sweats and seminal emission, internal heat with wasting-thirst, blood deficiency with sallow complexion, palpitations and severe palpitations, irregular menstruation, flooding and spotting, dizziness, tinnitus, and premature graying of beard and hair. Prepared Rehmannia charcoal tonifies blood and stops bleeding. Used for deficiency damage of the thoroughfare and conception vessels, and flooding and spotting.

Prepared Rehmannia Charcoal

[Processing] Take prepared Rehmannia, stir-fry until thick smoke rises, the surface swells and turns scorched black, and the interior is brownish-brown; then lightly spray with water, extinguish all sparks, take out, and air-dry.

[Characteristics] The surface is scorched black, the interior is dark brown, and the texture is relatively loose and brittle. Slight scorched odor, slightly bitter taste.

[Nature and Taste] Sweet, slightly astringent, slightly warm.

[Meridian Tropism] Liver and kidney meridians.

[Effects] Nourishes yin and tonifies blood, benefits essence and fills marrow.