Kampo (Japanese Herbal Medicine)
Chinese Herbs, Japanese Rigor, and the Insurance Card
Evidence grade 2 of 5, Thin. Read how the Atlas grades evidence.
Kampo occupies an unusually evidence-engaged position for a traditional system, though the evidence is still uneven. Because it is integrated into Japanese medicine, many Kampo formulas have been studied in clinical and laboratory research: yokukansan has been studied for behavioral and psychological symptoms of dementia, daikenchuto for post-operative gut function, kakkonto and hochuekkito for cold and respiratory symptoms, rikkunshito for upper-GI symptoms, and others, with some formulas showing promising results and entering practice guidelines. At the same time, much of the evidence is limited, mixed, or of modest quality, and the individualized "pattern" approach makes rigorous trials methodologically hard. The honest framing: Kampo is a traditional herbal system held to pharmaceutical quality standards and partly validated, some formulas have reasonable supporting evidence for specific uses, many are under-studied, and its key distinction is rigor and integration (standardization, regulation, physician prescribing) more than blanket proof of efficacy.
Reference only. Not medical advice.
What can go wrong
Kampo's standardization and physician oversight make it comparatively safer than unregulated herbal traditions, since the prescription extracts are GMP-grade and monitored, but it is still potent herbal medicine with real risks. Licorice, one of the most common ingredients, can cause pseudoaldosteronism, meaning low potassium, high blood pressure, and edema, especially at doses of licorice around 2.5 g per day or more, with prolonged use, and in women and older adults. Formulas containing ephedra carry cardiovascular and stimulant risk, and Japanese safety data link Scutellaria-containing formulas such as shosaikoto to rare drug-induced liver injury and to interstitial pneumonia, occasionally serious. Interactions with conventional drugs matter because Kampo is frequently used alongside them. Historically, some East Asian herbal use, including a few Japanese Kampo cases involving Boui and Mokutsu formulas, was tied to aristolochic-acid kidney injury and urinary-tract cancer before those herbs were banned. Kampo should be used under the guidance of a qualified, licensed medical provider, not self-prescribed, particularly during pregnancy, in children, for anyone with heart, kidney, or liver conditions, or alongside other medications; a clinician can check for interactions and monitor potassium and organ function.
Kampo is Japan's traditional herbal medicine, adapted from Chinese medicine that arrived via the Korean Peninsula around the 5th to 6th centuries and then developed along its own path for more than a millennium, centered on matching a herbal formula to a patient's overall pattern, called sho. What sets it apart from most traditional systems is how thoroughly it sits inside modern medicine: about 148 extract formulas are standardized, manufactured to pharmaceutical GMP, covered by national health insurance, and prescribed by conventional physicians, most of whom report using it. Because it is woven into mainstream care, several formulas have real trial data, with the clearest signals for yokukansan in dementia-related agitation and daikenchuto in gut recovery after surgery, though the results are honestly mixed and often subgroup-dependent. It remains potent herbal medicine, with documented risks from licorice, ephedra, and drug interactions, plus a sobering aristolochic-acid history. The fair read is a traditional pharmacy held to pharmaceutical standards and partly validated.
Japan's traditional herbal medicine, derived from Chinese practice but standardized to pharmaceutical quality, insurance-covered, and prescribed by conventional doctors.
What people take it for
These are the reasons people give for taking it. They are not effects it has been shown to have.
How it is supposed to work
Kampo formulas act through the combined pharmacology of their many plant (and some mineral/animal) constituents, often with several herbs intended to work synergistically and to temper each other's effects. The traditional "pattern" (sho) framework for matching formula to patient is a classical diagnostic model rather than a biomedical mechanism, though in practice many Japanese physicians prescribe Kampo formulas by conventional Western diagnosis. Individual formulas (e.g., kakkonto for early cold symptoms, yokukansan for agitation) have identifiable active compounds and biological effects under study.
What people get wrong
Often saidKampo is just Chinese medicine under a different name.
ActuallyIt descends from Chinese medicine but diverged over more than a millennium into a distinct Japanese system, with its own emphasis on abdominal diagnosis and fixed classical formulas. What truly separates it is institutional: about 148 formulas standardized to pharmaceutical GMP, insurance-covered, and prescribed by physicians, with Kampo in every Japanese medical school's core curriculum by 2005 (Moschik 2012 physician survey; Arai 2019 on legal status and quality assurance).
Often saidBecause Kampo is regulated and natural, it is essentially risk-free.
ActuallyIt is potent herbal medicine with documented harms. Licorice, one of its most common ingredients, can cause pseudoaldosteronism with hypokalemia and high blood pressure; ephedra-containing formulas carry cardiovascular and stimulant risk; and Japanese pharmacovigilance links Scutellaria-containing formulas such as shosaikoto to drug-induced liver injury and interstitial pneumonia. Regulation reduces but does not remove these risks (Shimada 2019 adverse-event analysis).
Often saidKampo's flagship formulas are backed by strong, settled trial evidence.
ActuallyThe evidence is real but mixed. The daikenchuto meta-analysis (Zhang 2018, 9 RCTs) called its own findings limited due to heterogeneity, and pivotal single trials were often negative or positive only in subgroups; the yokukansan meta-analysis (Matsunaga 2016) showed a modest benefit overall but none in Alzheimer's disease; kakkonto was non-superior to a standard cold remedy for the common cold.
Who profits, and who pushes back
Japanese medical system
Approves about 148 standardized Kampo formulas, covers them under national insurance, and has most physicians prescribing them within mainstream care.
Kampo clinical research
Reports promising evidence for specific formulas (yokukansan, daikenchuto, others) while noting much of the evidence is limited or mixed and individualized prescribing complicates trials.
Pharmacovigilance
Flags real risks including licorice-induced pseudoaldosteronism, ephedra cardiovascular effects, drug interactions, and rare liver or lung injury.
Integrative-medicine scholars
Highlight Kampo as a rare example of a traditional system standardized, regulated, and integrated within scientific medicine rather than practiced alongside it.
Where the research comes from
Most of the published research on this comes from one place. 92% of it is from Japan. Findings that no unrelated group has reproduced are weaker than the study count makes them look.
| Place | Share of published research |
|---|---|
| Japan | 92% |
| East Asia | 60% |
| Global (research interest) | 40% |
How we got here
The herbal medicine that became Kampo reached Japan from China across the Korean Peninsula around the 5th and 6th centuries, arriving alongside Buddhism, and was reinforced by direct missions to China in the 7th century. During the Edo period, when Japan largely closed itself off, physicians reworked the inherited Chinese texts into a distinctly Japanese system, emphasizing formula precision and abdominal palpation for diagnosis; Seishu Hanaoka even blended Kampo with Dutch surgical knowledge around 1804. The Meiji government's drive to modernize nearly ended it: a Western-oriented system was set up in 1874, licensing was restricted to Western-trained doctors by 1883, and in 1895 the Diet rejected a petition to keep Kampo, pushing it toward extinction. It survived at the grassroots and revived in the 20th century, with Kyushin Yumoto's 1927 Kokan Igaku a turning point. Crude drugs gained official pricing in 1960 and the first 33 formulas entered the national insurance list in 1976, growing to the roughly 148 in routine use today.
- 5th-6th c.Chinese herbal medicine reaches Japan via the Korean Peninsula, alongside Buddhism
- Edo period (1603-1868)National isolation lets Japanese physicians rework it into a distinct system with abdominal diagnosis
- 1874-1895Meiji modernization marginalizes Kampo: Western-favoring system (1874), Western-only licensing (1883), Diet rejects Kampo petition (1895)
- 1927Kyushin Yumoto publishes Kokan Igaku, a catalyst for the 20th-century revival
- 1976First 33 Kampo extract formulas added to the national health insurance drug price list
- 2005All Japanese medical schools have incorporated Kampo into their core curriculum
- TodayAbout 148 formulas are insurance-covered and used by a large majority of Japanese physicians
How it is understood
Kampo is the traditional herbal medicine of Japan, adapted from classical Chinese medicine, that arrived via Korea around the 5th-6th centuries, and then developed along a distinctly Japanese path over more than 1,500 years. The name means roughly "the way of the Han (Chinese)," distinguishing it from the Dutch-derived Western medicine that later entered Japan. Kampo emphasizes herbal formulas, complex combinations of crude drugs prescribed according to a patient's overall pattern (sho), and historically deemphasized acupuncture relative to Chinese practice. What makes Kampo unusual among traditional systems is its deep integration with modern medicine: Kampo formulas were standardized into a set of about 148 prescription extract preparations that are approved by Japan's health authorities, manufactured to pharmaceutical quality standards, covered by the national health insurance, and prescribed by conventional, fully trained physicians, the great majority of Japanese doctors use Kampo. It is less a parallel alternative system than a traditional pharmacy woven into mainstream Japanese healthcare.
At a glance
- Name
- "The way of the Han (Chinese)"
- Arrived
- Via Korea, 5th-6th centuries
- ~148 formulas
- Approved, insurance-covered prescriptions
- Distinction
- Integrated into mainstream Japanese medicine
What this entry does not yet cover
What follows is unfinished work on our side, not a finding about Kampo (Japanese Herbal Medicine). A short entry is not a safe entry.
- Cost and market. We have not documented what it sells for or who sells it.
- Supply chain. We have not mapped where it is made.
- Who uses it. We have not documented the user groups.
- What could change. No forward-looking summary yet.
- How it compares. We have not set it against the alternatives.
- Children and teenagers. We have not checked what is known about younger people.
Sources
About 148 Kampo formulas are insurance-covered, GMP-standardized with marker compounds, and government-surveilled
83.5% of Japanese physicians report using Kampo (2008 survey); all medical schools added Kampo to core curriculum by 2005
Moschik et al., Evidence-Based Complementary and Alternative Medicine (PMC3273038)
Yokukansan meta-analysis: 5 RCTs/361 patients, SMD -0.32 total BPSD and -0.37 agitation, but no benefit in Alzheimer's disease
Matsunaga, Kishi, Iwata, Journal of Alzheimer's Disease (PubMed)
Large placebo-controlled yokukansan trial for neuropsychiatric symptoms in Alzheimer's disease did not meet primary endpoint
Furukawa et al., randomized double-blind placebo-controlled multicenter trial (PubMed)
Daikenchuto meta-analysis: 9 RCTs/1,212 patients, shorter time to first flatus/bowel movement but limited evidence due to heterogeneity
Zhang et al., Annals of Surgical Treatment and Research (PubMed 29963534)
Individual daikenchuto RCTs (incl. JAPAN-PD) were largely negative on primary endpoints; benefit only in selected subgroup
Daikenchuto mechanism: TRPA1/TRPV1 agonism raises intestinal blood flow via adrenomedullin and CGRP
Kakkonto was non-superior to a standard multi-ingredient cold remedy for the common cold in an RCT
Okabayashi et al., non-superiority RCT (ResearchGate record)
Licorice/glycyrrhizin in Kampo causes pseudoaldosteronism (hypokalemia, hypertension); higher risk at >=2.5 g/day licorice
Scutellaria-containing Kampo formulas (e.g., shosaikoto) linked to drug-induced liver injury and interstitial pneumonia in Japanese pharmacovigilance data
Aristolochic-acid nephropathy: Japanese Kampo cases (Boui/Mokutsu) caused Fanconi-syndrome nephropathy; AA herbs banned worldwide after Belgian outbreak
Kampo history: arrival via Korean Peninsula 5th-6th c.; Meiji marginalization; 1976 first 33 formulas added to insurance
Ephedrine prohibited in-competition above 10 micrograms/mL urine; FDA banned ephedra supplements in 2004
US regulatory status: Kampo not FDA-approved as drugs; sold under DSHEA supplement framework; several INDs granted for study
Blumenthal/HerbalGram, 'Kampo: From Old Wisdom Comes New Knowledge'; FDA Dietary Supplements