Bupleurum (Chai Hu)

Table of Contents

1. What Bupleurum Is
2. Names: Chai Hu, Saiko and Radix Bupleuri
3. Traditional Uses
4. The Active Compounds
5. What the Laboratory Research Shows
6. What the Human Evidence Shows
7. Sho-Saiko-To and the Lungs
8. Liver Injury Reports and Interactions
9. Forms and Doses Used in Research
10. The Evidence in One Place
11. Who the Research Raises Concerns For
12. Open Questions
13. Key Research Papers
14. Connections
15. Featured Videos

What Bupleurum Is

The genus Bupleurum is large. A 2023 review counted about 248 accepted species spread across China, Japan, India, Central Asia, North Africa and parts of Europe, with 25 species and 8 varieties recorded as medicinal in traditional use. The plants look little like the carrot family's familiar umbrella-flowered members at first glance: many have simple, narrow, grass-like leaves with parallel veins, and small clusters of yellow flowers held on wiry stems.

Only a few species are official medicine. The dried roots of Bupleurum chinense DC. and Bupleurum scorzonerifolium Willd. are the two sources named for the medicinal material in Chinese practice, and most laboratory research uses one of them. Other species are used locally. Bupleurum marginatum, for example, is used by several ethnic minorities in south-west China, sometimes as the whole plant rather than the root; a 2026 review of it described market confusion, a lack of chemical markers that tell it apart from B. chinense, and no independent quality standard.

That variability is not a footnote. Reviewers from Heidelberg noted in 2011 that the large chemical and biological differences between species and varieties make standardization of bupleurum extracts "crucial" before the root could be integrated into conventional medicine, and that the root's clinical safety and interactions still needed to be evaluated.

Names: Chai Hu, Saiko and Radix Bupleuri

Because bupleurum crosses three languages and two medical traditions, the same material appears under several names in the research:

• Chai hu (Chinese) — the root as a single herb in traditional Chinese medicine.
• Saiko (Japanese) — the same root in Kampo, Japan's standardized system of formulas derived from Chinese medicine.
• Radix Bupleuri / Bupleuri Radix — the pharmacopoeial Latin used in most scientific papers.
• Xiao chai hu tang / sho-saiko-to / syo-saiko-to — "minor bupleurum decoction," the best-studied formula containing it. A 2006 case report from Taipei describes it as a mixture of seven herbal components: bupleurum root, pinellia tuber, scutellaria (Chinese skullcap) root, jujube fruit, ginseng root, licorice root and ginger rhizome, first prepared in the Han dynasty (Journal of the Chinese Medical Association, 2006).
• Xiao yao san ("free and easy wanderer powder") and chai hu shu gan san — two other bupleurum formulas, both studied mainly for mood. A 2018 review noted that bupleurum is marketed in China in chai hu shu gan tablets and xiao yao wan tablets.

When a study says "Bupleurum," it is worth checking which of these it means. Most clinical papers on this page tested a formula; most laboratory papers tested a single purified saikosaponin.

Traditional Uses

According to a 2023 review of the genus, the traditional record credits bupleurum species with treating fever, pain, liver disease, inflammation, pain in the chest and lower back, irregular menstruation and rectal prolapse. A 2024 review adds that chai hu has long been used in China, Japan and Korea as a jie yu (depression-relieving) medicine, and for liver conditions such as hepatitis and liver fibrosis.

In the vocabulary of Chinese medicine, the 2026 B. marginatum review summarizes the herb's described functions as "releasing the exterior and harmonizing the interior, soothing the liver and relieving depression, as well as uplifting middle qi," and classes it as pungent, bitter and slightly cold, associated with the liver, gallbladder and lung "meridians." These are traditional categories, not anatomical claims; the Chai Hu in Traditional Chinese Medicine deep dive explains what they mean and how they map, loosely, onto modern ideas.

Japan's Kampo medicine took one formula especially far. A 2000 review notes that shosaikoto was used clinically in Japan to treat patients with chronic hepatitis or cirrhosis. That widespread use in older patients with liver disease is the background to the safety reports described below.

The Active Compounds

Reviews agree on the main groups of chemicals in bupleurum root:

• Saikosaponins. Triterpene saponins (soap-like molecules built on a 30-carbon skeleton with sugars attached). Saikosaponins a, c and d are described as the major bioactive compounds, and saikosaponin b2 also appears in the research. They are the focus of almost all mechanism work.
• Volatile (essential) oil. Many small aromatic compounds; a 2019 review counted 158 volatile-oil constituents.
• Flavonoids such as rutin and quercetin, plus lignans and phenylpropanoids.
• Polysaccharides. Large sugar chains, studied for anti-ulcer activity.
• Polyacetylenes. A 2023 review identified these as possibly the main poisonous compounds in the genus.

The 2019 review reported that more than 281 components had been isolated from Radix Bupleuri, including 66 triterpenoid saponins. The 2011 Heidelberg review summarized the division of labour suggested by laboratory work: saikosaponins as immunomodulatory, anti-inflammatory and antiviral agents; polysaccharides as anti-ulcer; and various lignans as anti-proliferative (slowing cell growth). These are functions observed in cells and animals, not in patients.

What the Laboratory Research Shows

The saikosaponin literature is large and nearly all preclinical (cell culture and animals). It is worth knowing what it covers, and equally what it does not.

Inflammation

Saikosaponins appear in a 2025 review of anti-inflammatory saponins from herbs, alongside escin, ginsenosides and glycyrrhizin. In one mouse study, saikosaponin a reduced chemically induced colitis (a model of ulcerative colitis) and blocked an inflammatory switch called the NLRP3 inflammasome in immune cells called macrophages, apparently by acting on an enzyme of cholesterol metabolism. These are mice given a chemical irritant, not people with ulcerative colitis.

Liver and fat metabolism

In mice fed a high-fat diet with sugary water, saikosaponin d reduced fat build-up in the liver and fat tissue, apparently by switching on a fat-burning receptor (PPARα) and switching off a fat-making pathway. A 2018 review describes the same compounds as having "contradictory roles" in cell death, oxidative stress and liver fibrosis — protective in some experiments and harmful in others. The Saikosaponins and the Liver deep dive sets out both sides.

Muscle and kidney

In mice with surgically reduced kidney function, saikosaponins a and d lessened muscle wasting and oxidative damage, through a pathway (PI3K/AKT/Nrf2) that the researchers confirmed by blocking it in muscle cells.

Cancer cell work

Saikosaponin d is the most studied compound for cancer. A 2021 review described its anti-tumour activity as multi-targeted in laboratory models, and called it "potentially effective and relatively safe," while listing its toxic effects and calling for more in-vivo work. Two single studies illustrate the type of evidence: in cultured bile-duct cancer cells, saikosaponin d made the chemotherapy drug gemcitabine work better under stress-hormone exposure; in cultured stomach-cancer cells, it slowed growth and migration after a computer-based "network pharmacology" screen. Neither involved a single patient.

Brain and mood

In mice exposed to chronic unpredictable mild stress, a standard depression model, saikosaponin b2 reversed depression-like behaviour and reduced inflammation in the brain's immune cells (microglia). A 2024 review lists saikosaponins a and d, rutin, puerarin and quercetin among the antidepressant compounds studied in bupleurum, acting in laboratory models on serotonin, dopamine, NMDA receptors and the growth factor BDNF.

What the Human Evidence Shows

Human evidence for bupleurum exists only in the form of formula trials, mainly from China, and two systematic reviews capture it.

Depression

A 2020 systematic review and meta-analysis pooled randomized trials of bupleurum-containing formulas for major depressive disorder in adults aged 18 to 65. Thirty trials compared a formula with antidepressants, and 25 compared a formula plus antidepressants with antidepressants alone. On the Hamilton depression scale, the formula groups did better than antidepressants alone (standardized mean difference −0.35), and the combination did better than antidepressants alone (−1.03). Adverse events were fewer and milder in the formula groups. The authors were explicit about the limits: heterogeneity was high (I² 81% and 94%), study quality was low, and "the evidence is low quality and at risk of bias." The Xiao Yao San and Mood Research deep dive covers this in detail.

Chronic hepatitis B

A 2010 systematic review found 16 randomized trials of xiao chai hu tang in 1,601 people with chronic hepatitis B. One trial, published in English, was of good quality; the trials published in Chinese were of poor quality. Added to antiviral drugs, the formula was associated with more loss of viral markers and better liver tests than antivirals alone. Against placebo, though, xiao chai hu tang made no difference to viral clearance or liver function. The reviewers concluded that the potential benefits need confirmation in rigorous trials.

What is missing

There is no large, independent, placebo-controlled trial of bupleurum root alone for any condition among the studies reviewed for this page. A 2025 review of the herb stated that clinical data on its optimal dosage, routes of administration and safety "are still insufficient." That is the most accurate one-line summary of the human evidence.

Sho-Saiko-To and the Lungs

The most serious safety finding attached to bupleurum is not about the root alone but about the formula sho-saiko-to (xiao chai hu tang).

• A 2017 review of 73 published cases of pneumonitis caused by Japanese herbal medicines (1996–2015) found sho-saiko-to was the most frequently implicated formula (26% of cases). Most patients (89%) developed lung inflammation within three months of starting. Thirteen (18%) needed mechanical ventilation, and three (4%) died. The authors noted that the implicated formulas commonly contain skullcap and licorice; a 2022 case report names bupleurum and skullcap as the suspected ingredients (Internal Medicine, 2022).
• A 2020 analysis of Japan's national adverse-event database (2004–2018) found sho-saiko-to among the drugs with the strongest reporting signal for drug-induced interstitial lung disease, with a reporting odds ratio of 16.3, comparable to some cancer drugs; the median time to onset was 33 days, and the signal was stronger in older people.
• Japan's medicines regulator published, in 2008, the label wording for interferon preparations used against hepatitis C, which stated that because there had been many reports of interstitial pneumonia when sho-saiko-to was given at the same time, the combination was to be avoided (PMDA Pharmaceuticals and Medical Devices Safety Information No. 250, September 2008).

The full account, including what is and is not known about which ingredient is responsible, is in the Sho-Saiko-To and Interstitial Pneumonia deep dive.

Liver Injury Reports and Interactions

Bupleurum's reputation as a "liver herb" sits beside published reports of liver injury:

• A 2000 review of herbal hepatotoxicity listed sho-saiko-to among Chinese herbal medicines with reported liver toxicity, and noted the picture was "confused further" by evidence that some of its components protect the liver.
• A 2014 review of liver injury from Chinese herbal products listed chai hu, da chai hu tang and xiao chai hu tang among products with reported hepatotoxicity; a 2015 compilation of 77 publications counted syo saiko to / xiao chai hu tang among the 28 herbs and mixtures for which causality was established by a standard scale or a positive re-exposure test.
• A 2018 review of saikosaponins reported increased risks of overdose-induced acute liver toxicity and accumulation-related chronic liver toxicity from saikosaponins and the root; a 2021 review listed liver toxicity, nerve toxicity, red-cell destruction (haemolysis) and heart toxicity among the toxic effects of saikosaponin d in research.
• On drug interactions, a 2000 Lancet review listed decreased blood levels of the steroid prednisolone when taken with xiao chai hu tang, and the 2021 review noted that saikosaponin d can influence drug-metabolizing enzymes (CYPs) and the drug pump P-glycoprotein.

These findings matter most for people already living with liver disease, older adults, people on interferon or other immune-modifying treatment, and people on prescription drugs. Decisions about medicines and herbal formulas belong with a clinician who knows the full list.

Forms and Doses Used in Research

Bupleurum reaches people in four main forms: the dried, sliced root decocted (simmered) in water, usually with other herbs; granule or powdered formula extracts such as xiao chai hu tang, xiao yao san and chai hu shu gan san; standardized Kampo formula preparations in Japan; and, in research only, purified saikosaponins.

On amounts, the sources reviewed here offer little that is solid. The 2025 review states that clinical data on the optimal dose of bupleurum are insufficient, and the formula trials pooled in the depression and hepatitis B reviews used many different formulas, preparations and doses. The 2006 Taipei case report describes a woman who developed acute hepatitis after drinking a xiao chai hu tang decoction continuously for six weeks; her liver tests normalized two months after she stopped. No dose on this page is a safe or effective dose established by trials.

The Evidence in One Place

• Established: long traditional use; a well-mapped chemistry centred on saikosaponins; many anti-inflammatory, liver and nerve effects in cells and animals.
• Weak but present: formula trials in depression and chronic hepatitis B, rated low quality with high risk of bias by the reviewers who pooled them; against placebo, the hepatitis B formula showed no difference.
• Absent: independent trials of bupleurum alone; an established dose.
• Documented hazards: sho-saiko-to-associated interstitial pneumonia, including deaths, with a regulatory warning against combining it with interferon; liver injury reports; dose-related saikosaponin toxicity in research; an interaction with prednisolone.

The four Benefits deep dives take each strand further.

Who the Research Raises Concerns For

Drawing together the case series, database analyses and reviews above, the published research raises concerns mainly for these groups:

• People receiving interferon. Japan's regulator reproduced interferon label text stating that the combination with sho-saiko-to was to be avoided because of many reports of interstitial pneumonia.
• Older adults. The 2020 Japanese database analysis found the lung-reaction signal for sho-saiko-to rose with age; patients in the 2017 case review averaged 63.
• People with chronic liver disease. They were the main users of sho-saiko-to in Japan, and liver-injury reports with the formula and with chai hu exist. A new liver problem is hardest to recognize against an existing one.
• People taking prescription medicines. A reduced prednisolone level with xiao chai hu tang is reported, and saikosaponin d affects drug-handling enzymes and transporters in research.
• People in the first weeks to months of use. Most published lung reactions began within three months, with a median of about a month in the database.
• Pregnancy and breastfeeding. No source reviewed for this page reports safety data for bupleurum in pregnancy or breastfeeding; the evidence is simply absent.

Open Questions

1. Does bupleurum alone do anything in people? Every human trial reviewed here tested a formula.
2. Which herb drives the lung reaction? Reviews and case reports point at skullcap, bupleurum and licorice without settling it.
3. How much saikosaponin is absorbed? A 2021 review calls the oral bioavailability of saikosaponin d "still controversial," and a 2018 review says the metabolism of saikosaponins is "largely unknown."
4. Where does protection end and toxicity begin? The 2018 review names the "dose-pharmacological/toxic relationship" as a key gap.
5. Would the depression results hold up? The reviewers who pooled them asked for well-designed trials to validate them.
6. Which plant is in the bag? Reviews describe large variation between species and market confusion between related species.

Key Research Papers

1. Ashour ML, Wink M. Genus Bupleurum: a review of its phytochemistry, pharmacology and modes of action. The Journal of pharmacy and pharmacology. 2011;63(3):305-21. PubMed PMID: 21749378
2. Teng L, Guo X, Ma Y, et al. A comprehensive review on traditional and modern research of the genus Bupleurum (Bupleurum L., Apiaceae) in recent 10 years. Journal of ethnopharmacology. 2023;306:116129. PubMed PMID: 36638855
3. Sun P, Li Y, Wei S, et al. Pharmacological Effects and Chemical Constituents of Bupleurum. Mini reviews in medicinal chemistry. 2019;19(1):34-55. PubMed PMID: 29956627
4. Tian Y, Guo J, Jiang X, et al. Exploring the Therapeutic Potential of Bupleurum in Medical Treatment: A Comprehensive Overview. Pharmaceuticals (Basel, Switzerland). 2025;18(9). PubMed PMID: 41011202
5. Li X, Li X, Huang N, et al. A comprehensive review and perspectives on pharmacology and toxicology of saikosaponins. Phytomedicine : international journal of phytotherapy and phytopharmacology. 2018;50:73-87. PubMed PMID: 30466994
6. Yang X, Yu Z, Yang M, et al. Bupleurum marginatum Wall.: A comprehensive review of the traditional uses, phytochemistry, pharmacology, and quality control. Journal of ethnopharmacology. 2026;365:121575. PubMed PMID: 41881320
7. Zhou P, Shi W, He XY, et al. Saikosaponin D: review on the antitumour effects, toxicity and pharmacokinetics. Pharmaceutical biology. 2021;59(1):1480-1489. PubMed PMID: 34714209
8. Yang L, Shergis JL, Di YM, et al. Managing Depression with Bupleurum chinense Herbal Formula: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Journal of alternative and complementary medicine (New York, N.Y.). 2020;26(1):8-24. PubMed PMID: 31328996
9. Qin XK, Li P, Han M, et al. [Xiaochaihu Tang for treatment of chronic hepatitis B: a systematic review of randomized trials]. Zhong xi yi jie he xue bao = Journal of Chinese integrative medicine. 2010;8(4):312-20. PubMed PMID: 20388470
10. Enomoto Y Md, Nakamura Y Md PhD, Enomoto N Md PhD, et al. Japanese herbal medicine-induced pneumonitis: A review of 73 patients. Respiratory investigation. 2017;55(2):138-144. PubMed PMID: 28274529
11. Matsumoto K, Nakao S, Hasegawa S, et al. Analysis of drug-induced interstitial lung disease using the Japanese Adverse Drug Event Report database. SAGE open medicine. 2020;8:2050312120918264. PubMed PMID: 32528682
12. Teschke R. Traditional Chinese Medicine Induced Liver Injury. Journal of clinical and translational hepatology. 2014;2(2):80-94. PubMed PMID: 26357619
13. Teschke R, Zhang L, Long H, et al. Traditional Chinese Medicine and herbal hepatotoxicity: a tabular compilation of reported cases. Annals of hepatology. 2015;14(1):7-19. PubMed PMID: 25536637
14. Stickel F, Egerer G, Seitz HK. Hepatotoxicity of botanicals. Public health nutrition. 2000;3(2):113-24. PubMed PMID: 10948380
15. Fugh-Berman A. Herb-drug interactions. Lancet (London, England). 2000;355(9198):134-8. PubMed PMID: 10675182
16. Inoue M. Shosaikoto as a potential antiatherosclerotic agent. Drug news & perspectives. 2000;13(7):407-12. PubMed PMID: 12937613
17. Gu Y, Duan S, Ding M, et al. Saikosaponin D attenuates metabolic associated fatty liver disease by coordinately tuning PPARα and INSIG/SREBP1c pathway. Phytomedicine : international journal of phytotherapy and phytopharmacology. 2022;103:154219. PubMed PMID: 35691075
18. Wang X, Li S, Yu J, et al. Saikosaponin B2 ameliorates depression-induced microglia activation by inhibiting ferroptosis-mediated neuroinflammation and ER stress. Journal of ethnopharmacology. 2023;316:116729. PubMed PMID: 37277081

PubMed Topic Searches

1. PubMed: Bupleurum
2. PubMed: Saikosaponin
3. PubMed: Sho-saiko-to / xiao chai hu tang
4. PubMed: Bupleurum randomized trials

Connections

• Heart, Liver and Metabolic Herbs — the category this herb belongs to
• Bupleurum Benefits Deep Dive — the four detailed articles
• Sho-Saiko-To and Interstitial Pneumonia — the lung safety record
• Saikosaponins and the Liver — protection and toxicity
• Xiao Yao San and Mood Research — the depression trials
• Chai Hu in Traditional Chinese Medicine — the formulas and their logic
• Milk Thistle — the best-known Western "liver herb"
• Skullcap — Chinese skullcap is a sho-saiko-to ingredient
• Licorice — in sho-saiko-to and xiao yao san
• Ginseng — another sho-saiko-to ingredient
• White Peony — bupleurum's partner in xiao yao san
• Hepatitis B — the condition of the formula trials
• Interstitial Lung Disease — the lung reaction linked to sho-saiko-to
• Depression — the most-trialled modern use
• Fatty Liver Disease — studied in saikosaponin mouse work

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