Decoction of herbal medicine is a method of applying herbal medicine by decocting the medicine into the required liquid using a certain temperature and heating time. Patients often ask, “Should I wash the herbs before decocting? Should I soak the herbs before decocting? How much water should be added? How long should I boil it? What is the meaning of “decoction first and then decoction”? And so on.
Li Shizhen pointed out in “Compendium of Materia Medica” that “all medicines are not effective if the decoction is done recklessly, with poor water and fire, or if the fire is out of order”, which explains that the decoction method of Chinese medicine is directly related to the clinical efficacy of Chinese medicine.
A. Is it necessary to wash the herbs before decoction?
Since all herbs used in hospitals are currently refined small packaged tablets with few impurities and good quality, it is recommended that they do not need to be washed. There are also some herbs under the latter, such as sand, peppermint and thorny mustard, etc. The active ingredients are all some volatile ingredients, and the active ingredients will be lost a lot after washing, which will not achieve the effect needed for treatment. Some powdered Chinese herbs, such as pine flower powder, pu huang and qing dai powder, etc., this kind of herbs should not be washed before cooking, and the powder will be lost if washed, and the herbs will be lost.
B. Should I soak the herbs before decoction?
The herbs should be soaked in cold water at room temperature before decoction, so that the active ingredients can penetrate and diffuse to the outside of the tissue cells and avoid coagulation of proteins and starch pasting contained in the tissues of the herbs during heating and decoction, so that the active ingredients are not easily leaked out. Generally speaking, flowers, leaves and whole herbs can be soaked for 20 to 30 minutes, while herbs such as roots, rhizomes, seeds, fruits, ores and crustaceans can be soaked for 60 minutes. But note that the soaking time should not be too long, too long soaking time will lead to drug enzymatic decomposition or mold.
C. How much water should be added to a decoction?
Each dose of medicine is usually decocted 2-3 times, the first decoction can be more water, generally to diffuse over the surface of the medicine 3-5cm is appropriate, the second and third decoction can be slightly less water, each time the amount of decoction of medicine about 200-300mL, generally take one dose a day, the two or three decoction of the liquid combined, divided into 2-3 warm. For some prescriptions with more flavors, if the amount of water added is not enough, the decoction time will be too long, resulting in a dry decoction and not getting the amount of liquid needed for treatment.
D. How to control the fire and time of decoction?
There is a difference between “martial fire” and “civil fire” for decocting medicine, and it is called “martial fire” for rapid decoction and “civil fire” for slow decoction. “The decoction time should be based on the nature of the medicine.
The decoction time should be determined by the nature of the medicine, generally 30 minutes. The first decoction can be boiled for 15-20 minutes, and the second decoction can be boiled for 10 minutes. Too long a decoction time can lead to a large reduction of volatile active ingredients, which will not achieve the therapeutic effect.
Tonic medicine is first boiled with martial fire and then slow decocted with civil fire for 20-30 minutes for the first decoction and 30-40 minutes for the second decoction. The decoction should be stirred 2-3 times to prevent the underlying drug from scorching, and the scorched drug should not be taken. Note that prolonged decoction of herbal medicines will produce tannic acid, which acts as reverse adsorption and instead affects the concentration of the effective substances contained in the liquid itself; and the taste of the long-decoction liquid becomes worse and more difficult to take.
E. What is the meaning of “decoction first and then decoction later”?
Some Chinese medicines such as shells and ores should be decocted first, because these herbs have a solid texture and are difficult to decoct, so they should be broken up and decocted first, and boiled for about 20 minutes before other medicines, such as tortoise board, raw oyster, raw dragon bone, raw gypsum, etc. Toxic drugs, such as aconite and eucommia, should be decocted for a longer period of time and boiled for about 60 minutes before adding other drugs. For certain drugs with light weight and large quantity, such as rhizome, Xia Gu Cao, etc., it is appropriate to decoct the juice first to clarify it, and then decoct the rest of the medicine with its juice instead of water, with the prescription stating “decoction of soup instead of water”.
Some aromatic drugs should be decocted afterwards, because these herbs have volatile oil as the active ingredient, so if the decoction time is too long, the active ingredient will be almost lost and the treatment purpose will not be achieved. The “later” herbs are usually put into the same decoction for 5 minutes when they are about to be decocted to a predetermined amount, such as mint, sand, cardamom, etc. For all post-decoction drugs, they should also be soaked before decoction.
F. How to choose the time to take the medicine?
The general method of taking is to take half of it while it is warm, and then half of it 4-6 hours later, while the heat-clearing medicine is best taken after it has cooled. There are certain requirements for the time of taking herbal medicines, depending on the disease nature, location of the disease and the herbal medicine taken.
G. Select the appropriate time with the specific efficacy of the herbal medicine, the recommended time for different herbal medicines are as follows.
1. Steady-down and water-driven medicine: taking it in the morning on an empty stomach is not only conducive to the rapid entry of drugs into the intestines, but also can avoid frequent waking up in the evening to affect sleep.
2. Slow down the agent: it is advisable to take it before going to bed, so that the next morning defecation.
3. Deworming medicine, tapping medicine and other drugs for gastrointestinal tract diseases: should be taken before meals, because it is conducive to the digestion and absorption of drugs.
4. Tonic drugs: It is advisable to take them on an empty stomach to facilitate full absorption of the drug’s effects.
5. tranquilizers: should be taken 30 minutes to 1 hour before bedtime.
6. Astringent medicine: should be taken in the evening.
7. containing drugs that stimulate the stomach and intestines should be taken after meals.