The correctness of the method of decocting traditional Chinese medicine (TCM) is closely related to the efficacy of the treatment. When decocting TCM, the following issues should be paid special attention to.
First, the utensils. Sand pots or porcelain pots are preferred for decocting TCM, and metal utensils such as iron and copper should be avoided. This is because most medicinal materials undergo chemical changes when in contact with metal, which can affect the therapeutic effect of the medicine. Second, soaking. Before decocting, the medicinal materials should be soaked in water for 30 minutes to soften them. Boiling water should not be used directly, as the proteins in the medicine will quickly coagulate, affecting the extraction of the active ingredients of the TCM. As for the amount of water to be added, it should be determined based on the dosage of the medicine. Generally, the water level should slightly exceed the amount of medicine, so that the volume of the decoction per dose is about 150 milliliters. For children, the amount of decoction should be less, while for patients with heat-related diseases, it should be slightly more.
Attention should be paid to the heat during decoction. High heat can be used before boiling, but after the water boils, low heat should be used. At the same time, the pot should be covered to prevent the volatile components of the medicine from escaping. The time required for decoction varies depending on the nature of the medicine. For example, herbs that dispel exterior syndromes should not be decocted for a long time. Usually, boiling for 15 minutes is sufficient. For tonifying herbs with thick and nourishing properties, longer decoction time is appropriate. After boiling, simmering on low heat for about 1 hour will help dissolve the active ingredients of the medicine better. In addition, some highly toxic herbs can have their toxicity reduced or eliminated by long decoction on low heat, such as Aconiti Radix (Fuzi) and Pinelliae Rhizoma Praeparatum (Banxia). The decoction time for such herbs should also be slightly longer. After the decoction is done, the decoction should be filtered while hot, and each dose of medicine is generally decocted only twice.
Also, it is important to remember that certain minerals and shells in TCM need to be decocted first, such as Os Draconis (Longgu), Gypsum Fibrosum (Shigao), Ostreae Concha (Muli), Magnetitum (Cishi), Plastrum Testudinis (Guiban), and Carapax Trionycis (Biejia). They should be decocted for about half an hour first. On the other hand, some aromatic herbs, such as Menthae Haplocalycis Herba (Bohe), Agastachis Herba (Huo Xiang), and Uncariae Ramulus Cum Uncis (Gouteng), should be added towards the end. For drugs that are prone to sinking, carbonization, and becoming pasty, and are difficult to filter, such as Cinnabaris (Chishizhi) and Indigo Naturalis (Qingdai), they can be wrapped in gauze or put into a gauze bag and then decocted in the pot. For valuable, scarce, and highly volatile medicines, such as Margarita (Zhenzhu) and Bletillae Rhizoma (Sanqi), there is no need for decoction. They can be ground into fine powder and taken with the decoction. However, for Ginseng Radix (Renshen) and Cervi Cornu Pantotrichum (Lurong), heating and decoction are necessary to minimize loss. Some viscous and sugary drugs, such as Gelatinum Corii Asini (Ejiao) and Saccharum Flos (Yitang), have high viscosity and produce a lot of foam when decocted, which can cause bottom burning and affect the extraction of active ingredients of other drugs. Therefore, these drugs should be dissolved in the already decocted medicine. For drugs with easily extractable active ingredients, such as Cinnamomi Ramulus (Rougui) powder, it is best to make them into tablets, soak them in boiling water in a covered container, and then take them orally.
