Rhizoma Rehmanniae, also known as prepared Rehmannia, is the rhizome of the plant Rehmannia glutinosa, belonging to the family Scrophulariaceae. It is prepared by steaming and drying the rhizome nine times. It has a warm nature and a sweet taste. It enters the liver and kidney meridians and has the functions of nourishing the kidney yin, replenishing essence, and nourishing blood. Although prepared Rehmannia is a commonly used nourishing Chinese medicine in clinical practice, there are still several contraindications that need to be noted.
1. The decoction should not be prepared in copper or iron utensils.
The book "Leigong Paozhi Yaohexingjie" states: "After collecting fresh Rehmannia, remove the white skin, steam it in a magnetic pot with a willow wood steamer, spread it out to let the air dry, mix it with alcohol, steam it again, and then let it dry. Do not let it come into contact with copper or iron utensils, as it can cause kidney damage, white hair, and debilitation of the male essence and female defense mechanism." Prepared Rehmannia should not be prepared in copper or iron utensils, and should not be cooked in an iron pot or kettle. "Ya Jian" states: "If it comes into contact with iron utensils, it can cause kidney damage." As stated in "Bencao Congxin", it should be stored in porcelain containers because of its sweet taste and its preference for soft and moisturizing substances.
2. Avoid consuming radishes, white onions, and blood-related foods.
"Bencao Pinhui Jingyao" records: "Avoid radishes, white onions, white Chinese chives, and white garlic." "Yaoyao Fenji" states "Avoid radishes, onions, garlic, and blood-related foods." Radishes can reduce qi, and white onions have a pungent and dispersing nature, which can affect the nourishing effect of Rehmannia. Blood-related foods are rich in blood and flesh, and excessive consumption may lead to greasiness, so they should be avoided.
3. Not suitable for patients with typhoid fever.
In the case of typhoid fever, pathogenic factors enter from the outside and should be dispelled rather than nourished. As stated in "Shennong Bencao Jing Baizhong Lu," "In Zhang Zhongjing's 'Shanghan' book, there are 113 prescriptions, and only one uses Rehmannia. This is because in the case of typhoid fever, pathogenic factors enter from the outside and it is most important to avoid nourishing and stagnation. If it is used for tonifying, it must also have a dispersing and purging nature to be included in the prescription. Otherwise, the pathogenic Qi will be trapped inside and cause harm. Nowadays, when people see symptoms that are slightly related to deficiency, they often use Liuwei Decoction, which is killing people like crazy, which is truly regrettable."
4. People with spleen deficiency, phlegm accumulation, and qi stagnation should use it with caution.
Prepared Rehmannia has a sweet taste and is especially greasy. It should be used with caution in people with spleen deficiency, phlegm accumulation, and qi stagnation. "Bencao Congxin" states: "According to the fact that prepared Rehmannia is stagnating in nature, it should be used with caution in people with phlegm accumulation and qi stagnation, as it can obstruct the chest and diaphragm." "Bencao Zhengyao" states: "Prepared Rehmannia is stagnating in nature. If it is used in people with phlegm accumulation and qi stagnation, it can obstruct the chest and diaphragm, so it should be used with caution." "Bencao Tongxuan" states that "prepared Rehmannia is stagnating in nature, and in people with phlegm accumulation, it is feared that it will obstruct the diaphragm. It should be stir-fried with ginger juice to control its stagnation. It should also be combined with Amomi Fructus and Agarwood, both of which can promote the flow of Qi back to the kidneys and alleviate the stagnation of Rehmannia. This is the balancing act of medication."
