What is traditional Chinese herbal medicine?

Overview

The system of herbal medicine that developed in China differs in several significant ways from European herbal medicine. The most obvious difference is that Western herbal medicine focuses on simples, or herbs taken by themselves. In contrast, traditional Chinese herbal medicine (TCHM) makes almost exclusive use of herbal combinations. Also, TCHM formulas are not designed to treat symptoms of a specific illness; rather, they are tailored specifically to the individual according to the complex principles of traditional Chinese medicine (TCM). For this reason, TCHM is potentially a deeply holistic healing approach. However, it is both more difficult to use and harder to study than its Western counterpart.

TCHM is widely used in Asian countries, both in its traditional holistic form and in a simplified disease-oriented version. There have been a few properly designed scientific trials of TCHM, but the evidence base remains highly inadequate. In addition to questions regarding effectiveness, serious safety concerns need to be resolved.

History. Chinese herbal medicine has a long historical tradition, although it is not quite as ancient as popularly believed. Ancient herbology in China focused on potions whose functions were part medicinal and part magical, and it lacked a substantial theoretical base. Sometime between the second century b.c.e. and the second century c.e., the theoretical foundations of TCM were laid, but the focus was more on acupuncture than on herbs. Only by about the twelfth century were the deeper principles of Chinese medicine fully applied to herbal treatment, forming the method known as TCHM. This was further refined and elaborated during various periods of active theorizing in the fourteenth through the nineteenth centuries. Western disease concepts entered the picture in the twentieth century, leading to further changes.

In China today, TCHM is used alongside conventional pharmaceutical treatment. Considerable attempts have been made to subject TCHM to scientific evaluation; however, most of the published Chinese studies on the subject fall far short of current scientific standards. (For example, they generally lack a placebo group.)

In neighboring Japan, a variation of the TCHM system known as Kampo has become popular, and the Japanese health ministry has approved many Kampo remedies for medical use. The scientific basis for these remedies remains incomplete, but several studies of minimally acceptable quality have been reported.

Principles of traditional Chinese herbal medicine. According to the principles of all Chinese medicine, health exists when the body is balanced and its energy is freely flowing. The term “energy” refers to qi, the life energy that is said to animate the body. The term “balance” refers to the relative factors of yin and yang, the classic Daoist opposing forces of the universe. Yin and yang find their expression in various subsidiary antagonists such as cold versus heat and dampness versus dryness.

In an ideal state, yin and yang in all their forms are perfectly balanced in every part of the body. However, external or internal factors can upset this balance, leading to disease. Chinese medical diagnosis and treatment involve identifying the factors that are out of balance and attempting to bring them back into harmony. Diagnosis is carried out by means of “listening” to the pulse (in other words, taking the pulse with extraordinary care and sensitivity), observing and palpating various parts of the body, and asking a long series of questions.

It is important to realize that diagnosis according to TCHM differs greatly from Western diagnosis. Consider two hypothetical patients with the single Western diagnosis of migraine headaches. The first might be said to have “dryness in the liver and ascending qi,” while the other might be diagnosed with “exogenous wind-cold.” Based on these differing diagnoses, entirely different remedies might be applied. In other words, there is no such thing as a TCHM remedy for migraines per se; rather, treatment must be individualized to the imbalance determined by traditional theory.

The herbal formulas used in TCHM consist of four categories of herbs: ministerial, deputy, assistant, and envoy. The ministerial herb addresses the principal pattern of the disease. Deputy herbs assist the ministerial herb or address coexisting conditions. Assistant herbs are designed to reduce the side effects of the first two classes of herbs, and envoy herbs direct the therapy to a particular part of the body. For example, in the case of “dryness in the liver and ascending qi,” an herbalist might employ a ministerial herb to reverse ascending qi, a deputy herb to exert a moistening effect, an assistant herb to prevent the stagnation of qi (qi stagnation is said to be a side effect of moistening herbs), and an envoy to carry these effects to the liver.

TCHM remedies can also be designed to fit all common causes of migraines simultaneously, mostly by multiplying the number of ingredients. Practitioners of TCHM frown upon this “one-size-fits-all” approach, but it is often popular among consumers and is easier to test scientifically.

Types of Chinese herbal remedies. To use Chinese herbal medicine in the most traditional fashion, one must visit an herbalist’s shop. There, experienced herb preparers will chop, grind, fry, and slice dried herbs according to the prescription given by an experienced herbalist. The herbalist will provide a packet of dried herbs that need to be prepared according to the instructions, which typically involve adding water, boiling for several hours in a ceramic pot, pouring off the liquid, adding more water, and repeating the process twice more. Certain herbs are supposed to be added at the end of the process, while others require extra-long preparation.

If one does not wish to carry out such a complex process, or if a classic herbal shop is not available, one may wish to move one step away from tradition and purchase a prepared Kampo formula. There are several hundred such formulas designed to match the most commonly seen forms of imbalance. Available in powder, capsule, or tablet form, they can be used much more conveniently than fully traditional herbs. Many Kampo combinations are licensed in Japan and are manufactured there on a large scale by reputable manufacturers.

The lowest level of TCHM, scarcely deserving the name, involves Chinese patent remedies, which consist most commonly of tiny brown spheres in small brown bottles. They are marketed for both classical imbalances and Western disease categories. Patent remedies are inexpensive and widely available. However, there have been so many scandals involving dangerous contaminants not listed on the label that people should avoid this form of treatment entirely.

In the West, herbal medicine is part of folk medicine. However, in China, there is a distinct tradition of Chinese folk medicine that is separate from the orthodox, rather academic TCHM approach. In this Chinese folk medicine, herbs are used more simply, somewhat in the manner of Western herbal medicine. Herbs most commonly used in this manner include Astragalus, dong quai, ginger, kudzu (Pueraria lobata), licorice, Lycium, Panax ginseng, and Schisandra.

In addition to herbs, substances that are often considered supplements are utilized in TCHM. These substances include extract of human placenta, glandular extracts, and a variety of minerals.

Uses and applications. In the traditional system of Chinese herbal medicine, herbal formulas can be used to treat virtually any condition. Some of the most common uses in China include liver disease (hepatitis and cirrhosis), sexual dysfunction in men, infertility in women, insomnia, colds and flus, menstrual pain, irregular menstruation, and menopause.

Acupuncture is often used with herbs as a supplemental treatment; in addition, extraordinarily detailed lifestyle suggestions are common. It is not unusual for a traditional practitioner to “prescribe” dinner and to counsel changes in living situation (for example, move from the basement to the first floor or face the bed south rather than north). Exercise systems such as Tai Chi and qigong may also be recommended.

Chronic hepatitis. Hepatitis is a serious problem in many Asian countries, and conventional care is lacking. For this reason, herbal remedies are widely used.

The herbal combination Shosaiko-to (Minor Bupleurum) has been approved as a treatment for chronic hepatitis by the Japanese health ministry, and it enjoys wide use in that country and elsewhere. However, a search of the literature uncovered only one large-scale, double-blind, placebo-controlled study supporting its effectiveness. In this twenty-four-week trial, the efficacy of Shosaiko-to was tested in 222 people with chronic active hepatitis using a double-blind, placebo-controlled, crossover design. Results showed that the use of Shosaiko-to significantly improved liver function measurements compared with placebo. Although these results are promising, an absence of long-term evaluation limits their meaningfulness. (Researchers followed participants for three months only.)

Other Chinese herbal remedies have been tested as adjuncts to conventional interferon treatment with promising results. However, published trials are of generally poor quality. Persons undergoing interferon therapy should not use Chinese herbal formulas (or any herbs or supplements) except under the supervision of a physician.

Combination Chinese herbal therapies have also shown some promise for the treatment of chronic hepatitis; tested formulas include Bing Gan Tang, Yi Zhu decoction, Fuzheng Jiedu Tang, and Jianpi Wenshen recipe. However, the quality of most of these studies was quite poor. The results are mixed, and overall, the evidence for these remedies remains far too weak to rely upon. Two studies failed to find Chinese herbal treatment helpful for hepatitis C. Also note that there have been numerous cases of hepatitis and other forms of liver injury caused by Chinese herbs.

Liver cirrhosis
. Shosaiko-to has also shown some promise for preventing liver cancer and liver fibrosis in people with liver cirrhosis or chronic hepatitis. However, the evidence remains marginal. For example, in a double-blind, placebo-controlled study, 260 people with cirrhosis were randomly assigned to take Shosaiko-to or placebo, along with conventional treatment. In five years of evaluation, people taking the herb appeared to be less likely to develop cancer or die, but the results just missed the ordinary cutoff for statistical significance. For the subgroup of participants without hepatitis B infection, the benefits were statistically significant at the usual cutoff point.

Irritable bowel syndrome
. In a double-blind, placebo-controlled trial, 116 people with irritable bowel syndrome (IBS) were randomly assigned to receive individualized Chinese herbal formulations, a one-size-fits-all Chinese herbal formulation, or placebo. Treatment consisted of five capsules three times daily, taken for sixteen weeks. The results showed that both forms of active treatment were superior to placebo, significantly reducing IBS symptoms. However, the individualized treatment was no more effective than the generic treatment. Similar results also were seen in another study.

Constipation. The Kampo formula known as Daio-kanzo-to is a mixture of rhubarb and licorice. In a two-week, double-blind, placebo-controlled trial, 132 people with constipation were randomly assigned to one of three groups: placebo, low-dose Daio-kanzo-to, or high-dose Daio-kanzo-to. The results indicate that the higher-dose group, but not the lower-dose group, experienced statistically significant improvements in constipation compared with placebo.

Allergies. In a double-blind, placebo-controlled trial, 220 people with allergic rhinitis were given either placebo or the Kampo remedy Sho-seiryu-to for two weeks. The results showed that the use of the herbal formula significantly relieved all major symptoms of allergic rhinitis compared with placebo. Based on this and other more preliminary studies, Sho-seiryu-to has been approved by the Japanese health ministry for the treatment of allergic rhinitis and allergic conjunctivitis.

Another combination herbal therapy has shown promise for allergic rhinitis. In a twelve-week, double-blind, placebo-controlled trial, fifty-eight people with allergic rhinitis were given either placebo or an eleven-herb combination remedy called Biminne. This combination therapy contains the following herbs: Rehmannia glutinosa, Scutellaria baicalensis, Polygonatum sibiricum, Ginkgo biloba, Epimedium sagittatum, Psoralea corylifolia, Schisandra chinensis, Prunus mume, Ledebouriella divaricata, Angelica dahurica, and Astragalus membranaceus.

The use of Biminne produced significant improvements in some symptoms of allergic rhinitis, while other symptoms showed a trend toward improvement that was not statistically significant. A follow-up evaluation suggested that the results persisted for one year after treatment was stopped.

Benefits also have been seen in small studies of other formulations. However, one study failed to find that the use of herbal treatments augmented the effectiveness of acupuncture for allergic rhinitis.

Osteoarthritis
. A double-blind, placebo-controlled study of ninety-six people with osteoarthritis of the knee tested the effectiveness of a mixture of three Chinese herbs (Clematis mandshurica, Trichosanthes kirilowii, and Prunella vulgaris). Participants were randomly assigned to a placebo group or one of three other groups: given either 200 milligrams (mg), 400 mg, or 600 mg of the herbal formula three times daily. After four weeks of treatment, significant improvement in arthritis symptoms was seen in all three treatment groups compared with placebo. No dose appeared conclusively superior to the others.

Muscle spasms. The Kampo remedy Shakuyaku-kanzo-to is a combination of peony root and licorice, commonly used for the treatment of muscle spasms in general. In a double-blind, placebo-controlled study, 101 people with liver cirrhosis who also suffered from severe muscular spasms at least twice per week were given either Shakuyaku-kanzo-to or placebo three times daily for two weeks. (The herb combination is not specifically aimed at liver cirrhosis. However, people with liver cirrhosis often have muscle spasms, so it made sense to try an anti-muscle-spasm formula.) The results showed significant reduction in frequency and severity of spasms among the participants using the herb, compared with those taking placebo. However, some participants using the herb developed edema (swelling caused by excess fluid) and weight gain. Researchers attributed this side effect to the licorice constituent.

Menstrual pain. In a double-blind trial of forty women with menstrual pain, the Kampo formula Toki-shakuyaku-san was compared with placebo with good results. The design of this study was interesting because researchers preselected women who, according to the principles of TCM, would be expected to respond to this Kampo treatment. Through six menstrual cycles, women using the real herbal formula experienced significantly less menstrual pain compared with those in the placebo group. Benefits took three menstrual cycles to develop.

In a 2008 review of thirty-nine randomized controlled trials involving a total of 3,475 women, researchers concluded that the use of traditional Chinese herbs shows some promise in treating menstrual pain. However, firm conclusions were not possible because of the wide variability of study design and herbs used and because of the poor quality of many of the studies.

Diabetes
. A double-blind study of more than two hundred people evaluated the effectiveness of Coptis formula (a traditional combination therapy) with or without the drug glibenclamide for the treatment of diabetes. Coptis formula appeared to significantly enhance the effectiveness of the drug; however, the herbs produced marginal benefits at best when taken alone.

Asthma. The Kampo remedy Saiboku-to has been approved by the Japanese health ministry for the treatment of asthma. However, meaningful supporting evidence appears to be limited to one small trial. In this double-blind, placebo-controlled, crossover study, thirty-three people with mild to moderate asthma received Saiboku-to or placebo three times daily for four weeks. Treatment with the herbal remedy improved symptoms of asthma to a greater extent than placebo. Additional measurements suggested that Saiboku-to works by reducing asthmatic inflammation (technically, eosinophilia). A Chinese study using a proprietary formulation also reported benefits.

Eczema
. A Chinese herbal mixture sold under the name Zemaphyte has shown promise as a treatment for eczema. This formula, based on herbs traditionally used for skin conditions, contains the following: Ledebouriella seseloides, Potentilla chinensis, Akebia clematidis, Rehmannia glutinosa, Paeonia lactiflora, Lophatherum gracile, Dictamnus dasycarpus, Tribulus terrestris, Glycyrrhiza uralensis, and Schizonepeta tenuifolia.

In paired double-blind, placebo-controlled trials carried out by one research group, Zemaphyte produced significantly better effects than placebo for both adults and children. Each study enrolled approximately forty people and used a crossover design in which all participants received the real treatment and placebo for eight weeks each. The use of the herb significantly reduced eczema symptoms compared with placebo. However, a subsequent study of similar design performed by a different research group failed to find significant benefit with Zemaphyte. The reason for this discrepancy is not clear. In a twelve-week, double-blind study, a different traditional Chinese herbal formula also failed to prove more effective than placebo for treatment of eczema.

Tension headache. A topical ointment known as Tiger Balm is a popular treatment for headaches and other conditions. Tiger Balm contains camphor, menthol, cajaput, and clove oil. A double-blind study enrolling fifty-seven people with acute tension headache compared the application of Tiger Balm to the forehead with placebo ointment and with the drug acetaminophen (Tylenol). The placebo ointment contained mint essence to make it smell similar to Tiger Balm. Real Tiger Balm proved more effective than placebo and just as effective as acetaminophen. It also acted more rapidly.

Human immunodeficiency virus infection
. Chinese herbal therapies have been investigated for the treatment of human immunodeficiency virus (HIV) infection, but the results have not been very promising. In a twelve-week, double-blind, placebo-controlled trial, thirty persons with HIV who had CD4 counts of 200 to 500 were given a Chinese herbal formula containing thirty-one herbs. The results hint that the use of the herbal combination might have improved various symptoms compared with placebo, but none of the differences were statistically significant. Participants who believed they were taking the real treatment showed significant benefit regardless of whether they were in the placebo group or the real treatment group.

In another double-blind, placebo-controlled trial, sixty-eight persons with HIV were given either placebo or a preparation of thirty-five Chinese herbs for six months. The results indicate that the use of Chinese herbs did not improve symptoms or objective measurements of HIV severity. In fact, people using the herbs reported more digestive problems than those given placebo.

Prostate cancer. For several years, the Chinese herbal combination PC-SPES underwent significant investigation as a treatment for prostate cancer, with apparently impressive results. However, subsequent investigation revealed that PC-SPES contained undisclosed pharmaceutical ingredients (principally, a form of estrogen and the strong blood thinner Coumadin) and that these ingredients were probably responsible for its benefits. The treatment has since been withdrawn.

Other uses. A large double-blind study conducted in China reported that the use of the traditional remedy Xuezhikang by people with a previous history of a heart attack could reduce the risk that they would have a subsequent severe cardiovascular problem, such as a stroke or another heart attack. Chinese herbal medicine may also be helpful for people with angina. In a small, randomized trial of sixty-six adults with stable angina, Shenshao tablets (containing ginsenosides and white peony) reduced the frequency of angina attacks.

In a small, double-blind, placebo-controlled trial, the use of the herbal combination Banxia Houpo Tang (also called Hange Koboku-to or Magnolia and Pinelliae formula) was tested for the treatment of impaired cough reflex in people who had suffered a stroke. The results indicated that the herbal combination was more effective than placebo treatment for improving the coughing response.

In a review of twenty-one studies involving almost three thousand persons, researchers concluded that Chinese herbs were as effective as commonly prescribed medications for drug withdrawal symptoms in heroin addicts. They could not draw any conclusions, however, regarding what specific herbs were most beneficial.

Various Chinese herbal formulas have been evaluated for the treatment of respiratory infections. The results of published studies appear to indicate that these formulas are more effective than standard antibiotics, but the poor design of most of these trials precludes placing much faith in their outcomes. One combination therapy called Shuang Huang Lian has better supporting evidence than most.

A double-blind study performed in Hong Kong evaluated the potential benefits in cancer chemotherapy of personalized herbal formulas designed according to the principles of TCHM. In this study, 120 people undergoing chemotherapy for early-stage breast or colon cancer were given either a personalized formula or a placebo. Researchers evaluated numerous possible effects of the treatment but found benefits in only one: the reduction of nausea. Note that even this single result is less meaningful than it may seem; it is statistically questionable to use a multiplicity of outcome measures. A review of fifteen mostly poor-quality trials with 862 participants suggested that Chinese herbal medicine might improve quality of life in persons with non-small-cell lung cancer who are undergoing chemotherapy.

One study evaluated the effectiveness of an herbal combination containing herbs commonly used for the treatment of cough, but it failed to find the treatment effective. This study has been incorrectly reported as finding the tested treatment effective; indeed, the use of the treatment did help suppress coughing, but so did the placebo treatment, and there were no significant differences between the groups.

Numerous studies have evaluated TCHM for treatment of liver cancer with generally positive results. However, study design and reporting were markedly substandard.

A double-blind, placebo-controlled study of twenty-nine people with chronic fatigue syndrome found indications that the use of the Kampo remedy Hochu-ekki-to significantly improved symptoms compared with placebo. Also, the Kampo remedies Saiko-keishi-to and Shosaiko-to have been suggested for the treatment of epilepsy, but the supporting evidence is too preliminary to be relied upon. Both of these combination treatments consist of bupleurum, peony root, pinellia root, cassia bark, ginger root, jujube fruit, Asian ginseng root, Asian scullcap root, and licorice root, but the proportions are different.

Other traditional herbal combinations with some supporting evidence (often from studies of questionable quality) include Xiao-yao-san (Free and Easy Wanderer) for depression and bipolar syndrome, Mai-men-dong-tang for allergic asthma, Yi-Gan San for dementia, Bofu-tsusho-san for weight loss and diabetes, Chang Ji Tai for irritable bowel syndrome, Ondamtanggamibang (a Korean formulation) for reducing symptoms of stress, Qinzhu Liangxue for psoriasis, and red peony root for acute pancreatitis.

In one study, the herbal formula Duhuo Jisheng Wan, widely used for osteoarthritis, proved to be as effective as the standard anti-inflammatory drug diclofenac. However, the herb caused as many side effects as the drug, and it was slower to act. (It was so slow that its benefits could have been caused solely by the placebo effect.) This study did not use a placebo control group.

One double-blind, placebo-controlled study tested the remedy Hochu-ekki-to for enhancing immune response to influenza vaccine but failed to find benefit. One study quoted as showing that a Chinese herbal formula can reduce blood pressure actually failed to find any effect on blood pressure. A review of seventeen trials found that there is limited evidence to support the use of traditional Chinese herbal preparations for the common cold.

Safety Issues

There are several serious safety concerns with the use of TCHM. One concern involves the use of multiple herbs typical in this approach. In general, conventional medicine makes a point of using as few medications as possible (in theory, at least) because the greater the number of medications, the greater the risk of harm. Also, when medications are used together and harm does result, it is difficult to know what drug was at fault. From this perspective, formulas consisting of five, ten, or thirty herbs are quite worrisome.

Such combinations are actually designed for the purpose of reducing risks. According to TCHM theory, the various herbs in a formula balance and moderate each other. This theory, however, has never been put to the test, and there are reasons not to trust it. Simply put, it is very difficult to get an accurate picture of the risks of a treatment if one does not keep systematic records of adverse effects; the ancient Chinese government had no such system in place. In any case, the individualized nature of treatment would make it almost impossible to track harm. Herbalists would be expected to notice immediate, dramatic reactions to herbal formulas, and one can assume with some confidence that treatments used for thousands of years are unlikely to cause such problems in very many people who take them.

However, certain types of harm could be expected to easily elude the detection of traditional herbalists. These include safety problems that are delayed, occur relatively rarely, or are difficult to detect without scientific instruments. How would a traditional herbalist ever know, for example, if a treatment caused liver failure in 1 of every 100,000 people who used it, especially if such failure took two or more years to develop? If such a death did occur in the herbalist’s patient population, it would probably be attributed to hepatitis or some other common cause.

These factors may explain why Chinese herbal medicine traditionally uses treatments that are now recognized as potentially dangerous, such as mercury, arsenic, lead, licorice, coltsfoot, and Aristolochia clematis. Mercury, arsenic, and lead accumulate slowly in the body, and for many years their harm can only be detected by laboratory tests. Licorice (used in many herb formulas to “harmonize” the ingredients) can raise blood pressure and disturb blood chemistry. These effects were presumably undetectable to traditional practitioners unless the effects became quite severe. The herb Aristolochia can cause severe kidney damage and kidney cancer, but only rarely. Modern medical surveillance has uncovered quite a few such cases, but traditional herbology considered the herb worth using. Aristolochia contains aristolochic acid, a substance shown in animal studies to damage the kidney when taken in high enough doses. Chinese herbal products generally list Aristolochia on the label when it is present, but in some cases, Aristolochia was apparently added accidentally (it is similar in appearance to a much safer herb).

Coltsfoot (Tussilago farfara), used in Chinese cough syrups and other formulations, contains pyrrolizidine alkaloids, substances that can, over time, damage the liver. This also does not appear to have been noticed by traditional herbalists. Under modern conditions of medical surveillance, many incidents have been reported in which the use of Chinese herbs appears to have caused various forms of liver injury, including acute hepatitis, chronic hepatitis, hepatic fibrosis, and acute liver failure. Ancient herbal practitioners might not have been able to distinguish these herb-induced illnesses from the effects of infectious hepatitis, a widely prevalent condition, and thereby failed to make the connection. Even today, it appears that many cases of liver failure attributed to hepatitis have been caused by the Chinese herbs used to treat hepatitis. Other reported complications of Chinese herbal treatments include movement disorders and ovarian failure.

Another set of potential problems arises from Chinese herbal medicine not restricting itself to plant products with subtle effects. Many traditional Chinese herbal remedies are, simply put, poisons. When taken in proper doses, they may be safe for use, but dosage miscalculation or use in a particularly susceptible person may lead to serious consequences, including death. For example, in Hong Kong, poisoning caused by the herb aconite (used in numerous Chinese herbal formulas) was sufficiently widespread that public health authorities launched an information campaign to combat the problem.

Besides toxicity caused by Chinese herbs, other problems have been caused by adulteration of herbal products with unlisted ingredients. For example, the Chinese herbal formula PC-SPES, used for prostate cancer, turned out to contain three pharmaceutical drugs: diethylstilbestrol, warfarin (Coumadin), and indomethacin. This appears to have been an intentional adulteration designed somewhat along the lines of a traditional Chinese formula, with one pharmaceutical adulterant that treated prostate cancer balanced by two others to offset the side effects of the first. The combination is dangerous and has caused at least one case of severe bleeding.

In another episode, eight of eleven Chinese herbal creams sold in the United Kingdom for the treatment of eczema were found to contain strong pharmaceutical steroids. Other studies have also found steroids in eczema preparations. In addition, Chinese herbal weight-loss aids have been found to contain an unlisted chemical related to the appetite-suppressant drugs fenfluramine and phentermine (Fen-Phen).

Herbal products approved by the Japanese government have undergone meaningful safety testing and are unlikely to contain known toxins or unlisted drugs. However, this does not mean they are completely safe. For example, several case reports suggest that therapy for chronic hepatitis combining an approved herbal formula with the standard drug interferon can cause severe inflammation of the lungs. The herbal formulas Takeda Kampo Ichoyaku K-matsu, Taisho Kampo Ichoyaku, and Kanebo Kampo Ichoyaku Hused, all used to treat upset stomach, might reduce the effectiveness of the Parkinson’s disease medication levodopa.

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