Commonly Confused Medicinals
by Eric Brand
This week I’ve been teaching classes on herbal pharmacy at a variety of schools in Southern California. Herbal pharmacy is a subject that fascinates me, and I’ve been surprised to see that even the best students at the best schools often lack training in key issues of herbal pharmacy, such as the differentiation of authentic vs. substitute and counterfeit medicinals. While some of the issues related to herbal substitution are primarily only important from the perspective of quality and efficacy, some of the substitutions represent important issues of herbal safety.
To a certain degree, schools cannot be expected to train students the art and science of herbal pharmacy. Pharmacy and clinical medicine are separate fields in China, and Chinese medicine is too diverse of a subject to expect mastery across several different disciplines, particularly within the first four years of school. Many experienced practitioners in both Asia and the US know how to effectively prescribe herbs yet are not necessarily trained in quality discernment, species identification, and other elements of herbal pharmacy. Knowledge of herbal pharmacy issues is a subspecialty within Chinese medicine; nonetheless, because Western practitioners often must double as both doctor and pharmacist, there are a few issues from the field of pharmacy that are important for clinicians to stay abreast of.
Herbal safety is an important aspect of ethical practice. The substitution of herbs is often unintentional, and many substitutions reflect regional preferences. In particular, Cantonese pharmacies often stock southern variants of medicinals that differ from the item that is officially classified in the Chinese Pharmacopoeia. The traditional Cantonese substitute medicinals are the ones that are the most common on the US market; in fact, Cantonese substitutes are generally more common in Chinatown herbal pharmacies than their official Chinese Pharmacopoeia counterparts are. In most instances, the pharmacist is unaware that the herb stocked is not the authentic, official product.
To a certain extent, many regional substitutes cannot be considered inauthentic medicines. Some regional variations reflect differences in the official pharmacopoeias of different nations. For example, the formula si wu tang (four substances decoction) has only four ingredients, but two of the ingredients (dang gui and chuan xiong) are derived from different official plants according to the Chinese Pharmacopoeia, the Korean Pharmacopoeia, and the Japanese Pharmacopoeia. Even within Chinese regions alone, most regional substitutes are true medicinal herbs with their own entries in larger encyclopedias of Chinese herbal medicine, such as the Zhong Yao Da Ci Dian (Great Encyclopedia of Chinese Medicinals).
Some commonly confused medicinals share the same action as the primary medicinal, and may be safe and acceptable substitutes. Others differ from the main herb in terms of medicinal action. Some of these substitutes are generally benign while others are toxic. Substitutes that are fundamentally non-toxic but differ in medicinal nature may result in ineffective treatment or unwanted side effects. Toxic substitutes may cause severe poisoning, and hundreds of people have died worldwide from improper herbal substitutions.
On the US market, the most common herbs with substitute species can be divided as follows below. Once I learn how to add photos to the blog, I will give each one a separate entry with photographs to illustrate their differences. The definitive book on this subject is Easily Confused Chinese Medicines of Hong Kong, by Dr. Zhao Zhongzhen. The core information can also be found in my book, Concise Chinese Materia Medica, as well as the 3rd Edition of Bensky, Clavey, and Stoger’s Materia Medica. The issue of counterfeits is worth many other blogs of its own, so I will not get into counterfeit products here.
Almost all of the items below have extremely common substitutes on the market. For the herbs listed below under “acceptable substitutes” and “unacceptable but largely non-toxic substitutes,” the substitute species are generally more prevalent than the real item. Many practitioners use the wrong herbs when dispensing these products, unless they are using products made in a GMP factory or they buy from a supplier than is vigilant about the issue of species identification. The list below is incomplete; there are many misidentified herbs on the market, but these are the most common ones that we see confused in the US.
Fortunately, most of the dangerous substitutes are very rarely seen on the marketplace, with the notable exception of san qi.
Items that share a similar therapeutic effect as the main medicinal but are derived from a species other than the official product listed in the Chinese Pharmacopoeia include:
He Huan Hua (Cantonese substitute is a magnolia flower with similar TCM action to quiet the spirit, but lacks the qi-coursing action of the true product. Also more expensive than the official medicinal)
Jin Qian Cao (Southern variant is often more common than the main medicinal, regarded as very effective)
Ban Lan Gen (Southern variant is often more common than the main medicinal, regarded as very effective)
Unacceptable substitutes in terms of TCM action (but largely non-toxic):
The following items have substitutes that differ in traditional therapeutic effect from the main medicinal, but the mistaken herbs are generally not regarded as being particularly dangerous. In many cases, the substitute herb has not been studied extensively from a chemical and clinical perspective.
Chuan Niu Xi
Bai Wei/ Bai Qian
Ji Xue Teng/ Hong Teng (Da Xue Teng)
Bai Tou Weng
Wang Bu Liu Xing
These items have toxic substitutes that are unacceptable for use. With the exception of san qi, most of the toxic substitutes are rarely seen on the US marketplace. Each individual case deserves its own blog and several have been blogged about before, but I will still list them here. Also, read about xi xin in its earlier blog entry.
Fang Ji (must use han fang ji, also known as fen fang ji (stephania), and must rule out the presence of aristolochia root, known as guang fang ji, which contains aristolochic acid)
Mu Tong (Safe species is chuan mu tong, Armand’s clematis. Akebia is also safe but is rare on the market. Must rule out guan mu tong, Manchurian aristolochia, which contains aristolochic acid)
San Qi (see a previous blog, must rule out Rhizoma Tupisra)
Long Dan Cao (dangerous substitute is called gui jiu. Fortunately it is not commonly dispensed)