This is complicated further by dispensing herbs in mixtures such as patent formulas with 15 or 20 separate herbs. Because of all these factors, it can be very difficult to know exactly which drugs are involved in Chinese medicine . If you have a dozen standard references handy, it is possible to determine some of the ingredients with a fair degree of accuracy. However, many ingredients simply cannot be determined because of errors or inadequacy of the herb name, or because of the possibility of herb substitution. It is not easy to gather primary research references and to ferret out the best or most relevant research papers dealing with Chinese herbs and formulas.
Some research identifies an herb only by vernacular pinyin or English name.
Other papers report on herbs that are identified only to a botanical genus, giving no indication of which species were used. Almost no papers indicate that herb substitution was rigorously checked for and ruled out. Many papers report on patent formulas, and some of these do not list specific ingredients for proprietary, commercial reasons. All research on mixtures of herbs, regardless of quality of experimental design, must be treated with caution because of the chemical cocktail problem mentioned above . Few research papers pay enough attention to the problem of multiple names for particular herbs and the difficulties this presents in searching the literature, as for example in doing Medline searches.