First decoction and backward decoction are two different ways of decocting Chinese medicines. First decoction means that the Chinese medicines are put in to be decocted before other medicines are put in, while backward decoction means that the medicines are put in to be decocted after other medicines have been decocted for a certain period of time. Different decoction methods are due to the different traits of different drugs.
The first decoction mainly refers to some goldstone, mineral and crustacean herbs whose active ingredients are difficult to dissolve in water, which need to be broken and decocted first, such as magnetite, gypsum, oyster, mother-of-pearl, etc., as well as some poisonous drugs that need to be decocted first to reduce their toxicity, such as epiphyllum and chuanwu.
The latter is the last to be decocted for some aromatic drugs, which will cause the active ingredients to evaporate if decocted for a long time, so the latter is to reduce the time of decocting, such as mint.
The decoction of Chinese medicine needs to pay attention to the decoction of special drugs, the patient can ask the doctor in advance, whether there is a special decoction of drugs, and strictly in accordance with the implementation.