Kampō Medicine

Transmission from China and the Gosei-ha school

Kampo grew out of Chinese herbal medicine. Terasawa, a physician who led one of the first university Kampo departments in Japan, writes that the official history dates the arrival of the Chinese herbal system, by way of the Korean peninsula, to 552 AD, while noting that many unofficial exchanges probably also took place. In his account, Japanese practice remained largely a copy of contemporary Chinese herbal medicine until about the eighteenth century. A 2020 review by physicians at a Japanese pain center repeats the 552 AD date.

Japanese historians of medicine identify Tashiro Sanki and Manase Dosan (1507-1594) as founders of the Gosei-ha school, which brought to Japan a Jin- and Yuan-dynasty Chinese method of examining the patient's condition and then deciding treatment. A study of Dosan's compilation Ishin shoden describes how he moved from adjusting existing prescriptions to writing a new prescription for each treatment, and reports that his successors did not keep this practice.

Edo-period restoration and the Koho school

Terasawa places a turning point in the early to middle eighteenth century, during the Tokugawa (Edo) era, when Japanese scholars in several fields went back to original texts and questioned speculative neo-Confucian readings. In medicine, Yoshimasu Todo urged a return to the original spirit of Chinese medicine, favored simple prescriptions over theory and is reported to have said that medicine was nothing more than effective prescriptions. Terasawa traces modern Kampo to this Koho, or old-formula, school, while adding that its most radical positions did not become orthodox.

The same author credits Yamawaki Toyo, a Kampo physician, with testing the Chinese anatomical scheme against direct observation of a human body, around the time Japanese physicians began to learn Western medicine through Dutch traders. Terasawa writes that the word Kampo, which he translates as Chinese-style, was coined in this period to set the tradition apart from Dutch-style (Rampo) medicine.

Meiji exclusion and the 1970s revival

After the Meiji Restoration of 1868, the government adopted a German model for official medical education and practice and excluded Kampo from it. Both Terasawa and the 2020 review describe this as part of a wider program of modernization; Terasawa attributes it mainly to the visible advantages of Western medicine in areas such as vaccination and military surgery. He writes that the public kept using Kampo herbs and that university chemists continued to study them, including work on ephedrine around 1900.

Both sources describe a revival around 1970. Terasawa links it to an aging population with chronic disease, public concern about synthetic drug harms after the thalidomide disaster, and advocacy by Taro Takemi, then president of the Japanese physicians' association, which led to insurance coverage of Kampo extracts in 1976. Shimada adds that four prescription Kampo formulations first entered the national drug price list in 1967, with large additions in 1976, 1978, 1981 and 1984.

What the name covers

Kampo is a Japanese term that Terasawa translates literally as Chinese-style. He cautions that it is not a general word for Japanese medicine, and he argues that Kampo herbal medicine and acupuncture had different origins and were historically practiced by separate professional guilds, so they should not be treated as two halves of one system. He characterizes Kampo as a simplified and pragmatic version of Chinese herbal medicine that leans less on yin-yang and Five Elements theory than practice in China does. This is the view of one scholar-practitioner rather than a settled consensus.

Sho and the core categories

The central concept, according to Terasawa, is sho, which he renders as symptom, sign or evidence. Sho works as both a diagnosis and an indication for a formula, so a physician may describe a patient as being in a rikkunshito sho, meaning a state in which that formula is expected to help. He describes three paired categories, yin-yo (yin-yang), kyo-jitsu (hollow-full) and netsu-kan (heat-cold), and three substances: ki (qi), ketsu (roughly blood) and sui (roughly body fluids). A 2020 review summarizes the same framework.

Terasawa stresses that sho can shift within hours and does not map one-to-one onto biomedical diagnoses. One disease may correspond to several sho, and one formula may be used across many conditions; his example is daisaikoto, used for conditions as varied as gastritis, sinusitis and eczema. These passages describe how the tradition reasons. They are not tested claims about outcomes.

Prescription extract products

In present-day Japanese clinical use the word often refers to manufactured extract products rather than herbs brewed for each patient. Arai describes most prescription Kampo as dried extract granules in single-dose pouches, which many physicians prescribe much like other drugs. Shimada counts 148 prescription Kampo formulations available under national health insurance, plus about 200 crude drugs that can be used to prepare decoctions; Terasawa's 2004 account gives 147 prescriptions approved in 1976.

Traditional examination

Traditional Kampo diagnosis uses four observational approaches, which Terasawa lists as visual observation, listening to sounds made by the body, smelling and touching, and listening to what the patient reports. He writes that Kampo physicians gave special weight to the pulse and the abdomen, and the 2020 pain review names abdominal examination (fukushin) and tongue examination (zetsushin) as principal techniques. Terasawa adds that many fine palpatory distinctions are learned from experienced teachers in clinical practice rather than from texts.

How physicians in Japan prescribe it

Arai's 2021 review states that among nationally licensed practitioners in Japan, only physicians may diagnose and treat with traditional medicine alongside Western treatment. Most Kampo treatment now consists of physicians prescribing extract products on the basis of a biomedical diagnosis, alone or with conventional drugs, without a traditional diagnosis. Terasawa explains that insurance-covered prescribing must be tied to biomedical disease names such as gastritis or atopic eczema.

Reported uptake among physicians is high. Shimada cites a 2011 manufacturers' association survey in which 89 percent of physicians said they prescribed Kampo, and an education study states that more than 90 percent do so. The 2020 pain review notes that patients in Japan can receive Kampo and Western care in the same institution at the same time.

Training and professional bodies

Terasawa reports that national medical education guidance in the early 2000s recommended that all medical schools include an overview of Kampo in the core curriculum; he gives both 2002 and 2003 in the same article. Arai notes that physicians still receive only limited university teaching on Kampo, and Ito and colleagues describe significant challenges in delivering it. Their e-learning program contains 88 lessons written by 54 Kampo specialists, and 86.4 percent of 88 responding fourth-year students at one medical school were satisfied with a session that used it.

Arai describes the Japan Society for Oriental Medicine as the largest academic organization devoted to Kampo in Japan; it has published structured Evidence Reports of Kampo Treatment since 2007. The sources reviewed here do not describe a specialist certification pathway, so this page does not report one.

Uses as the tradition frames them

Within the tradition, formulas are matched to sho rather than to disease names. Terasawa argues that this approach may be useful for complex or poorly understood conditions and gives atopic dermatitis and chronic fatigue syndrome as examples. Shimada reports a traditional view that prescribing according to sho improves efficacy and lowers the risk of adverse effects, but he adds that adverse effects occur even when a formula is judged appropriate by Kampo diagnosis.

Uses studied in Japanese clinical research

Arai's review of the clinical literature found that cancer was the most common research field, with most trials aimed at symptoms after surgery or side effects of anticancer drugs rather than at tumors. Rikkunshito and daikenchuto were the formulas most often tested in randomized trials, and daikenchuto, rikkunshito and yokukansan were the most often registered. Daikenchuto has been studied for bowel function after abdominal surgery, yokukansan for behavioral and psychological symptoms of dementia, and rikkunshito for functional dyspepsia.

The 2020 pain review describes Kampo use for neuropathic, low back, osteoarthritis, neck and shoulder, and orofacial pain, citing mostly retrospective surveys, small case series and laboratory studies. Arai notes that 1980s case reports promoted shosaikoto for chronic hepatitis and saireito for nephrotic syndrome. A listed use shows how a formula is applied; it is not evidence that the formula is effective for that condition.

The overall evidence base

A 2011 review of 135 Kampo clinical studies collected by the Japan Society for Oriental Medicine up to January 2009 found that two thirds enrolled fewer than 100 patients, that overall methodological quality appeared low, and that none used Kampo diagnosis as the basis for treatment. Arai reported in 2021 that the society's evidence reports included 488 randomized trials; of 369 comparative trials, 74 percent showed a statistically significant effect on some outcome, and only 7.1 percent of 378 analyzed trials used sho to select patients or formulas.

Arai also notes that prescription Kampo products were approved without clinical trials, on the basis of long experience with decoctions, that many trials were funded by manufacturers, and that the results of most registered Kampo trials had not been reported. He wrote that trials run abroad by manufacturers seeking approval outside Japan had not produced positive results to that date.

Daikenchuto after abdominal surgery

A 2025 meta-analysis of 11 randomized trials with 1,413 patients having gastroenterological cancer surgery found a shorter time to first flatus with daikenchuto; the abstract reports a mean difference of -0.19 (95% CI -0.34 to -0.04) without stating units, and the authors judged the effect modest and called for higher-quality trials. In a US phase 2 trial of 392 patients after elective bowel resection, daikenchuto (TU-100) at 7.5 g a day did not significantly change the primary end point, time to gastrointestinal recovery (hazard ratio 1.17, 95% CI 0.91 to 1.50).

In that US trial, median hospital stay was 2 days with the 7.5 g dose and 3 days with placebo, and early nausea and bloating were rated less bothersome, but the 15 g dose showed no significant differences from placebo. The authors describe the findings as encouraging trends that need further study.

Yokukansan for dementia-related symptoms

In a double-blind, placebo-controlled multicenter trial in 145 people with Alzheimer's disease, yokukansan at 7.5 g a day did not significantly change total Neuropsychiatric Inventory scores at 4 or 12 weeks, though a subgroup with lower cognitive scores showed a greater fall in agitation and aggression. A 2016 meta-analysis of five randomized trials with 381 patients found a small reduction in total symptom scores compared with placebo or usual care (standardized mean difference -0.32), no benefit in the trials limited to Alzheimer's disease, and no difference in discontinuations or adverse events.

Rikkunshito for functional dyspepsia

In a multicenter trial of 247 patients, 33.6 percent responded at 8 weeks with rikkunshito and 23.8 percent with placebo, a difference that was not statistically significant (p = 0.09), although epigastric pain improved significantly. A later trial randomly assigned 128 patients without Helicobacter pylori infection and found better global treatment efficacy at 8 weeks with rikkunshito than with placebo (p = 0.019). Both trials lasted 8 weeks and do not establish longer-term effects.

Interstitial pneumonia and liver injury

Shimada's 2021 review states that Kampo medicines were long regarded as relatively safe but are drugs with serious adverse effects. Interstitial pneumonia linked to shosaikoto was first reported in 1989, and Arai reports 10 deaths by 1996 and 8 more by 2000. Shimada writes that about 70 percent of reported lung-injury and liver-injury cases involved formulas containing Scutellaria root (ogon), and cites incidences of 0.27 percent for interstitial pneumonia and 1.0 percent for liver injury in patient series given such formulas.

In a Japanese survey of drug-induced interstitial lung injury from 2004 to 2009, Kampo medicines accounted for 233 of 7,598 cases (3.1 percent). According to Shimada, about 80 percent of Kampo-related interstitial pneumonia begins within two months of starting a formula, while liver injury can appear from days to a year later, often with non-specific symptoms. Shosaikoto labeling lists contraindications including use with interferon and in cirrhosis or liver cancer.

Licorice and pseudoaldosteronism

Licorice is present in 109 of the 148 prescription formulations. Its glycyrrhizin can cause pseudoaldosteronism, with edema, high blood pressure and low potassium that may progress to muscle injury, arrhythmia or heart failure. Shimada names shakuyakukanzoto and yokukansan as the formulas most often reported, and warns that several licorice-containing formulas prescribed by different clinics can add up to an overdose. Product labeling cautions against combining them with loop or thiazide diuretics.

Other reported harms and care boundaries

Shimada also describes sympathomimetic effects from ephedra, aconite poisoning from processed aconite root, diarrhea from rhubarb, and mesenteric phlebosclerosis after years of taking gardenia-containing formulas, with onset reported after at least four years of use. He notes adverse effects from over-the-counter Kampo products, some sold under other names, and states that approved Japanese Kampo products do not contain aristolochic acid, unlike some imported products.

The sources reviewed describe Kampo in Japan as prescribed and monitored by physicians, with laboratory and clinical checks for some formulas. They do not support using it to replace or delay necessary medical care.