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Traditional Chinese medicine

BupleurumBupleurum chinense

Bupleurum (chai hu) leads Xiao Yao San (6 dyspepsia trials, RR 1.15 vs drugs); the Kampo formula sho-saiko-to was behind 26% of 73 reported herbal pneumonitis cases.

Botanical name
Bupleurum chinense
Part used
root, dried; often vinegar-fried
Also called
pinyin Chai hu (柴胡); Chinese thoroughwax, Hare’s ear root, Bupleuri radix, Saiko (Japanese)
Used in
Traditional Chinese medicine
Taken for
Stress and the gut, Cramping and pain, Bloating, Liver and bile
Sold as
decoction, pill, granule extract, patent medicine, dried slices

What is meant by bupleurum

Bupleurum, or chai hu, is the dried root of Bupleurum chinense and the related B. scorzonerifolium, plants of the carrot family. A review in BioMed Research International says the root has been used for more than 2,000 years in China, Japan, Korea and other Asian countries, and that it contains triterpenoid saponins (the saikosaponins), essential oils, polyacetylenes, flavonoids and lignans. Chai hu is also often cut and fried with vinegar (cu chai hu), a preparation the tradition uses to direct the herb toward the liver.

In the digestive formulas it is the lead of Xiao Yao San (sold as the pill Xiao Yao Wan) and of Chai Hu Shu Gan San, and it is in Xiao Chai Hu Tang, the formula that Kampo calls sho-saiko-to. The first two share an idea: the tradition holds that the gut cramps and bloats when emotional strain makes liver qi stagnate. The root is taken as a decoction, a pill, a granule extract, and in patent medicines, almost always with other herbs.

In the traditions

Traditional Chinese medicine (about TCM)

Chai hu is given in the materia medica as bitter, acrid and slightly cold, entering the liver and gallbladder channels, with the actions of releasing the exterior, clearing heat at the shaoyang level, spreading liver qi and raising yang qi. For the gut the tradition uses it where it sees liver qi stagnating and pressing on the spleen: flank and abdominal distention, cramping, irritability, alternating constipation and loose stools, and a sense of a lump in the throat. Xiao Yao San pairs it with dang gui, white peony, white atractylodes, poria, licorice, ginger and mint for what the texts call liver constraint with spleen deficiency. Liver qi stagnation is the tradition’s pattern name and not a diagnosis in Western terms.

What the plant contains

The saikosaponins (a, b2, c, d) are the compounds most studied. A review in BioMed Research International reports anti-inflammatory, antipyretic, antiviral, hepatoprotective and immunomodulatory effects in cell and animal studies, and the same review reports that the root can cause hepatotoxicity, particularly in high doses and with long-term use. Pharmacokinetic work in rats showed that the major saikosaponins were absorbed rapidly after an oral extract. These are laboratory and animal findings, and we found no human trial that tested a single bupleurum compound for a gut outcome.

What has been tested in people

We could not find a controlled trial of bupleurum root alone for a gut outcome. The human data are formulas that contain it, and the studies are open to bias.

The most direct are the Xiao Yao San trials for functional dyspepsia. A meta-analysis of 6 trials with 707 people found a higher total clinical efficacy rate than Western medicine (RR 1.15, 95% CI 1.05 to 1.26; heterogeneity high), a greater reduction of dyspepsia symptom scores (SMD -0.72) and fewer adverse events (RR 0.20). An earlier analysis of 14 trials found an odds ratio of 3.26 against prokinetic drugs, and the authors said publication bias and flawed methods may have amplified it. A network meta-analysis of placebo-controlled trials ranked Xiao Yao Pill as probably having a large benefit on global dyspepsia symptoms (risk difference 0.37, 0.03 to 0.99). For modified Chai Hu Shu Gan San, 22 trials with 1,998 people gave RR 1.20 (1.14 to 1.27) against prokinetics, and every included trial was at high risk of bias.

Most of these pooled analyses compare the formula with active drugs; the network analysis is the one built only on placebo-controlled trials, and its confidence interval is wide (0.03 to 0.99).

Not tested: bupleurum root alone for any digestive symptom, and Xiao Yao San in a large placebo-controlled IBS trial, which we could not find.

StudyDoseWhat it found
Meta-analysis of 6 RCTs, 707 people with functional dyspepsia (Xiao Yao San vs Western medicine) PMID 37124216Formula; doses variedTotal efficacy RR 1.15 (1.05 to 1.26); dyspepsia score SMD -0.72; adverse events RR 0.20
Meta-analysis of 14 RCTs, functional dyspepsia (modified Xiao Yao San vs prokinetic drugs) PMID 19702899Modified formula; doses variedSymptoms OR 3.26 (2.24 to 4.47); authors flag publication bias and methodological flaws
Network meta-analysis of 15 placebo-controlled RCTs, 12 formulas, functional dyspepsia PMID 34592339Formulas; doses variedXiao Yao Pill: global symptoms risk difference 0.37 (0.03 to 0.99)
Meta-analysis of 22 RCTs, 1,998 people with functional dyspepsia (modified Chai Hu Shu Gan San vs prokinetics) PMID 23762161Modified formula; doses variedRR 1.20 (1.14 to 1.27); all trials at high risk of bias
Case series review, 73 patients with Japanese herbal medicine-induced pneumonitis PMID 28274529Not applicableSho-saiko-to was the cause in 26%; 3 patients (4%) died; 36% recovered by stopping the medicine

Doses used in trials and traditional preparations

None of the abstracts we read gives a bupleurum dose that can be separated from the rest of the formula. The traditional preparation is a water decoction of the sliced root, raw or vinegar-fried, simmered with the other herbs and drunk in divided doses. Xiao Yao San is also sold as pills and granules, and sho-saiko-to is sold as a standardized extract in Japan. The hepatotoxicity noted in a review of the root occurred at high doses with long-term use.

Treat these figures as a record of what was studied. Whether any amount of bupleurum suits a particular person is a question for a clinician or pharmacist who knows their history.

Safety

The notable finding is pneumonitis with Kampo formulas. A review of 73 cases of Japanese herbal medicine-induced pneumonitis found sho-saiko-to responsible in 26 percent; 36 percent recovered after stopping the medicine, 18 percent needed mechanical ventilation and 4 percent (three patients) died. Those formulas also contain scutellaria and licorice, and a Chinese review concluded that several factors were involved, including use with interferon. Liver injury at high doses over long periods is noted in a review of the root. Separately, aristolochic acid is not a constituent of bupleurum, but bupleurum is an ingredient of Long Dan Xie Gan Tang, which also calls for mu tong, a name that has been applied to Aristolochia manshuriensis; European regulators recorded renal failure from that substitution, including 17 Chinese cases, 12 of them fatal.

Drug interactions

The pneumonitis cases are the interaction signal that matters: the Chinese review of the sho-saiko-to episode points to combined use with interferon as one contributing factor, and a Japanese case review links several formulas that contain scutellaria and licorice. No controlled interaction study of bupleurum root with a medicine turned up. Xiao Yao San and its relatives also contain licorice, whose potassium and blood-pressure effects apply to the finished formula.

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Related herbs

TCM White peony Paeonia lactiflora TCM Atractylodes Atractylodes macrocephala (bai zhu); A. lancea (cang zhu) TCM Poria Wolfiporia cocos (syn. Poria cocos) TCM Dang gui (Chinese angelica) Angelica sinensis Ayurvedic / TCM / Western Licorice Glycyrrhiza glabra

The questions that come up

What is Xiao Yao San?

It is a classical formula led by bupleurum, with dang gui, white peony, white atractylodes, poria, licorice, ginger and mint. In the texts it is for liver qi stagnation pressing on a weak spleen, which includes cramping, bloating and mood-related digestive trouble.

Does bupleurum help with dyspepsia?

A meta-analysis of 6 trials in 707 people found the Xiao Yao San formula better than Western medicine on efficacy (RR 1.15). The comparison was not against placebo, and the authors rated the evidence from very low to high by outcome.

Why is bupleurum linked to lung problems?

The Kampo formula sho-saiko-to was behind 26 percent of 73 reported cases of herbal pneumonitis in Japan. The formulas involved also contain scutellaria and licorice, and a Chinese review says several factors, including interferon use, were involved.

Can bupleurum harm the liver?

A review of the root notes hepatotoxicity at high doses with long-term use. The Chinese review found no reports of interstitial pneumonitis or drug-induced liver injury from bupleurum formulas in Chinese literature.

Is chai hu the same as the bupleurum in supplements?

Supplements are often extracts and may name a different species from the Pharmacopoeia roots. The traditional use is the sliced root in a decoction with other herbs.

Sources