Rehmannia Root Powder (Rehmannia glutinosa) is the finely milled form of one of the most important yin-nourishing herbs in Traditional Chinese Medicine (TCM), known as Shēng Dì Huáng (生地黄) when used raw. This deeply cooling, moistening root is treasured for its ability to clear heat, cool the blood, generate fluids, and nourish yin, making it a foundational herb for conditions involving internal heat, dryness, thirst, blood deficiency, or irritability. Raw Rehmannia is sweet, bitter, and cold, offering a soothing, cooling influence on the Heart, Liver, and Kidney channels. In TCM, Sheng Di Huang is traditionally used to cool the blood, ease feverish heat, reduce thirst, and calm irritability or restlessness caused by warm-disease heat or yin depletion. It is also a key herb for nourishing fluids, supporting conditions such as dry mouth, dry throat, wasting and thirst disorders, and constipation from yin deficiency. Its blood-cooling quality makes it valuable for skin eruptions, rashes, nosebleeds, or bleeding due to heat entering the blood level. Raw Rehmannia also gently enriches Blood and nourishes yin, supporting the Liver and Kidneys during states of depletion, dryness, dizziness, or fatigue. It is commonly combined with herbs like Moutan, Scrophularia, and Anemarrhena in classical heat-clearing formulas, or with tonic herbs for long-term yin cultivation. In folk use, Rehmannia Root Powder is added to cooling herbal drinks, restorative pastes, and fluid-generating tonics, especially during hot seasons or situations of dryness. Modern research shows that Rehmannia glutinosa contains iridoid glycosides, catalpol, rehmanniosides, polysaccharides, and antioxidant compounds with anti-inflammatory, hepatoprotective, hypoglycemic, and blood-cooling effects. These constituents support its traditional ability to nourish yin, generate fluids, reduce heat, and protect organ function. Each batch of Rehmannia Root Powder (Rehmannia glutinosa) is carefully processed to preserve its deep brown color, smooth texture, and cooling, yin-enriching properties. When mixed with warm water or decocted into formulas, it produces a rich, earthy, cooling liquid used to clear heat, nourish yin, moisten dryness, and cool the blood.