Rehmannia glutinosa has a sweet and slightly bitter taste, and is cold in nature, belonging to the category of cold and cooling medicines. Its main functions are to cool the blood, clear heat, nourish yin, and tonify the kidneys. Below, we will introduce in detail the specific effects of Rehmannia glutinosa as a cold and cooling medicine.
1. Cooling Blood and Clearing Heat: Rehmannia glutinosa is sweet, bitter, and cold in nature. It can cool the blood and clear heat, and also stop bleeding. It is most commonly used for febrile diseases when heat evil invades the nutritive or blood level (high fever, delirium, purplish-red tongue with little saliva, rashes, or hematemesis, epistaxis, daytime restlessness, and a thready and rapid pulse). It is often used in combination with Scrophularia ningpoensis, Forsythia suspensa, Gardenia jasminoides, Curcuma longa, Lophatherum gracile, Paeonia suffruticosa, Paeonia lactiflora, Gypsum fibrosum, and Rhinoceros horn, such as in Qingying Decoction, Huaban Decoction, and Rhinoceros Horn and Rehmannia Decoction. According to modern research reports, Rehmannia glutinosa has a hemostatic effect and can promote blood coagulation.
2. Nourishing Yin and Tonifying the Kidneys: This product nourishes Yin and tonifies the kidneys, and can be used for symptoms such as bone steaming fever, dry cough, sore throat, blood in sputum, hot palms and soles, and night sweats caused by Yin deficiency with heat. It is often used in combination with Lycium chinense root bark, roasted turtle shell, Moutan bark, Gentiana macrophylla, Anemarrhena asphodeloides, Cynanchum paniculatum, Scrophularia ningpoensis, and Asparagus cochinchinensis. In addition, in the later stages of febrile diseases, for symptoms such as thirst, loss of appetite, afternoon fever, and evening fever with morning coolness caused by heat damaging body fluids, this product can also be used in combination with Ophiopogon japonicus, Polygonatum odoratum, Adenophora stricta, pear juice, rock sugar, lotus root juice, raw barley malt, roasted barley malt, and fragrant rice malt to nourish Yin, generate fluids, clear heat, and benefit the stomach. For thirst caused by Yin deficiency and inability to overcome heat (thirst with a desire for cold drinks, but not quenching thirst, gradual weight loss, frequent urination, and easy hunger), it is often used in combination with Rehmannia glutinosa, Cornus officinalis, Dioscorea opposita, Poria cocos, Moutan bark, Alisma plantago-aquatica, Schisandra chinensis, and Trichosanthes kirilowii.
Rehmannia glutinosa, also known as raw Rehmannia, is mainly used to cool the blood, clear heat, nourish yin, and generate blood. When roasted to charcoal, it is called Rehmannia glutinosa charcoal, mainly used to stop bleeding. Rehmannia glutinosa steamed with rice wine is called processed Rehmannia glutinosa, mainly used to tonify the kidneys, nourish yin, and nourish blood. Rehmannia glutinosa dug from the soil, washed, and used immediately is called fresh Rehmannia glutinosa, which is extremely cold in nature and mainly used for febrile epidemic diseases, symptoms such as feverish delirium caused by excessive heat and toxicity in the blood. There are also small or fine Rehmannia glutinosa varieties, which nourish yin without being greasy, suitable for the later stages of febrile diseases, and for cases of insufficient yin and poor appetite.
Raw Rehmannia root has a rich and greasy flavor. When taken in large quantities or for a long time, it can easily cause stagnation and impair appetite. In this case, it is advisable to use finely ground Rehmannia root; or to combine it with some Amomum villosum, or to stir-fry it with ginger juice. Combined with Ophiopogon japonicus, it moistens the lungs and clears heat; combined with Asparagus cochinchinensis, it nourishes the kidneys and reduces fire; combined with Scrophularia ningpoensis, it detoxifies, clears heat, and cools the blood; combined with rhinoceros horn, it cools the blood and removes spots.
The usual dosage is three to five qian (approximately 15-12 grams); for severe cases, one liang (approximately 30 grams) or more can be used. Fresh Rehmannia glutinosa is usually used at one to two liang (approximately 30-60 grams). It should not be used by those with spleen and stomach deficiency and cold, or loose stools; it is also contraindicated for those with excessive summer heat and dampness, chest tightness, and loss of appetite.
