The common administration of Chinese medicinal herbs may be oral, external or local. Forms of decoction, pill, powder, soft extract, and wine, etc., are prepared for oral use, while application, moxibustion, pigmentum, lotion, laryngeal insufflation of medicinal powder, eye drops, thermotherapy, and suppository, etc, are used exteriorly. Whereas the form of decoction is still most widely used at present, which are generally prepared by patients. Therefore doctors should tell their patients or patient's relatives how to decoct medicinal herbs in order to ensure desired effects in clinical application of medicinal herbs.
Methods of decocting Chinese medicinal herbs
Stewing utensils available are clay pot or earthen jar or a piece of enamelware. The water available must be clean and without peculiar smell. First Chinese medicinal herbs are put into the enamelware and water is added into it, the water should submerge the surface of the herbs. Before being decocted, the Chinese medicinal herbs needs to be immersed in water for half an hour so as to make their medicinal components easily dissolve in the solution. Fire used in decocting the herbs should be controlled in the light of medicinal properties and qualities. The medicinal herbs with aromatic smell should be decocted with strong fire until the solution is boiled for several minutes, then a mild fire is followed until the decoction is done, otherwise the medicinal effects will reduce; medicinal herbs for nourishing, since their qualities are greasy, should be decocted with a mild fire for a long time，otherwise the effective factors are not easily decocted out. A dose of Chinese medicinal herbs is taken daily, which is usually decocted twice while nourishing ones may be decocted three times, and the decocted juice should be about 250 - 300 ml.
Since their qualities and properties are usually obviously different, different medicinal herbs should be given different treatment in decocting method and time. When a prescription is made out, the methods should be noted, so as to be followed by drug store or patients when the solution is decocted. The chief methods are shown as follows.
Being decocted first: some kinds of minerals and shell medicines, such as Shigao (Gypsum Fibrosum), Cishi (Magnetium ), Shijueming ( Concha Haliotidis ) and Biejia (Carapax Trionycis ) must be decocted first for 10 - 30 minutes, then the other kinds are put in, since they are hard in qualities and their effective components are not easily decocted out. The method is also applied to decocting or boiling poisonious medicinal herbs, such as Wutou (Radix Aconiti ) and Fuzi ( Radix Aconiti Lateralis Praeparata) thus their poisonous effects may be lessened or eliminated.
Being decocted later: Some aromatic medicinal herbs such as Bohe (Herba Menthae), Sharen (Fructus Amomi ), Gouteng (Ramulus Uncariae cure Uncis ) and Shengdahuang (Radix et Rhizoma Rhei ) with volatile components must be added after the solution of the other medicinal herbs has been boiled for 10 - 30 minutes, and then boiled another 5 minutes or so.
Boiling of wrapped herbs: Some medicinal herbs must be wrapped in a piece of cloth or gauze, and then put together with others in enamelware into which water is added. The method is mainly applied to the following medicinal herbs; the herbs, if decocted directly in water will make their decoction turbid which is difficult to be taken orally; some medicinal herbs of small seeds, after boiled, will float on the decoction and not be removed easily; some downy herbs, if decocted directly in water, will make their decoction mixed with tomentum , which can not be removed easily and can irritate the throat when the decoction is taken. For instance, Chishizhi (Halloysitum Rubrum ), Feihuashi ( Talcum ), Cheqianzi ( Semen Plantaginis ) and Xuanfuhua ( Flos Inulae ).
Decocting or boiling singlly: The Chinese medicinal herbs, such as Renshen (Radix Ginseng) and Lingyangjiao (Cornu Saigae Tataricae ) must be decocted or boiled separately, which is mainly applied to some precious medicines in order to prevent them being absorbed by other ingredients when they are decocted or boiled with other medicinal herbs.
Melting: Put the medicinal herbs to be melted into the decoction that has been boiled well and hasn't contained dregs of decoction and the medicinhal herbs being stirred together until they are melted well for oral use. Besides, the medicines can also be melted by steaming in the container with water, and then the melted ones are mixed with the decocted juice without dregs for oral use. The method is mainly applied to the medicine containing a lot of mucilage and easily soluble ones, such as Ejiao ( Colla Corii Asini ), Guibanjiao ( Colla Plastri Testudinis) and Yitang (Saccharum Granorum ). If decocted directly together with other herb medicines in water, they will be deposited at the bottom of the pot or stick to the other ingredients and not be easily filtered.
Oral taking with water: Some medicines that are dissolved as soon as they are put into water, such as Mangxiao (Natrii Sulfas). Some kinds of juice medicine such as Zhuli (Succus Phyllostachydis Henonis ), Fengmi (Mel) and Yitang (Saccharum Granorum), and those that are got by grinding such kinds of medicines as Lingyangjiao ( Cornu Saigae Tataricae ) , Chenxiang (Lignum Aquitariae Resinatum) with water do not need decocting and are suitable to be mixed directly with water or the decocted juice for oral use.