Shengdi and ripeneddi differ in their efficacy, main treatment and method of preparation. Shengdi is mainly used for feverish diseases, while ripeneddi is mainly used for tonifying blood and nourishing yin.
Shengdi is the tuberous root of Di Huang, a plant of the family Xuan Shen family. Its effects are clearing heat and promoting generation of body fluid, cooling blood and stopping bleeding (cooling and moistening the blood to prevent bleeding). It is mainly used for treating hematemesis and epistaxis caused by blood heat; fever of warm diseases that enters the camp, such as heat in the body and heat at night, disturbances and insomnia, and vague macular rash (slight macular rash on the skin); dryness of the mouth and throat, intestinal dryness and constipation caused by heat diseases that injure the yin; and fever caused by deficiency of yin.
Radix Rehmanniae Praeparata is made from the raw ground that has been processed and steamed. It is used to tonify blood and nourish yin, benefiting the essence and filling in the marrow. It is used for treating blood deficiency with yellowish color, irregular menstruation or amenorrhea, lumbar and knee soreness, dizziness and vertigo, night sweating, seminal emission and premature whitening of hair.
The adverse effects of Radix Rehmanniae Praeparata and Radix Rehmanniae Glutinosa are not known. Raw Radix should not be used if the spleen is deficient in dampness and stagnation, or if the abdomen is full of loose stools (thin and unformed feces); and the use of Radix Rehmanniae is contraindicated if there is stagnation of qi and phlegm, distension and pain in the epigastrium (abdomen), or if the stomach is full of loose stools. Drugs need to be used under the guidance of a doctor, and should not be taken blindly on their own.