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Cang zhu

Atractylodes lancea

Also calledCangzhu (Chinese) · Sojutsu (Japanese, Kampo) · Khod-kha-mao (Thai) · Atractylodis Rhizoma (pharmacopoeial name)

In older monographsAtractylodes chinensis, Atractylodes japonica, Atractylis lancea, Atractylis chinensis

The aromatic rhizome cang zhu, one of the classic 'damp-drying' herbs of Chinese medicine, recorded since the Shennong Bencao Jing and still an official drug of the Chinese, Japanese and Korean pharmacopoeias; in Japan it is the Kampo ingredient sojutsu. A Thai research group has developed a standardised capsule for bile-duct cancer, but its clinical results come from one group and part of its preclinical work has since been retracted.

What it is used for

Cancer: drugs and supportive care
Limited
A standardised capsule extract was well tolerated in a phase I placebo-controlled study in 48 healthy Thai volunteers (1,000 mg daily for up to 21 days). The same group reports a phase 2A study in advanced intrahepatic cholangiocarcinoma with less tumour progression and mortality at 1,000–2,000 mg daily than palliative-care controls. In 2026 the group's preclinical paper on the capsule was retracted and another paper received an expression of concern, so these results need independent confirmation.^2,3,4,5
Indigestion and dyspepsia
Traditional
In Chinese medicine it 'strengthens the spleen and dries dampness', treating digestive discomfort from 'dampness obstructing the middle'; the Japanese and Korean pharmacopoeias list it as a gastroprotective. In animals the extract and β-eudesmol sped gastric emptying; no good human trials of the single herb.¹
Fluid retention
Traditional
Used as a diuretic in Kampo (sojutsu, e.g. in Saireito) and in Japanese and Korean pharmacopoeial tradition.¹
Eyes
Traditional
The Chinese Pharmacopoeia credits cang zhu with 'improving vision', and it was historically a core remedy for night blindness.¹
Fever
Traditional
In Thailand khod-kha-mao is used mainly for fever, common colds and non-infectious digestive upset.¹

How it is prepared

decoction

In Chinese medicine the rhizome (often stir-fried or bran-fried to temper its dryness) is decocted, usually within multi-herb formulas.

dry extract / capsule

Capsules of a standardised ethanol extract developed in Thailand for research in cholangiocarcinoma.

Doses studied: 1,000 mg daily in healthy volunteers (phase I); 1,000–2,000 mg daily in advanced cholangiocarcinoma (phase 2A, Na-Bangchang group).

Cancer: drugs and supportive care

Amounts are as recorded by the named source, not a recommendation.

Safety

Pregnancy: Insufficient data
Breastfeeding: Insufficient data

Interactions with medicines

CYP2C19 and CYP3A4 substratesModerateβ-eudesmol is a substrate and inhibitor of both enzymes in human liver microsomes; high doses of the capsule extract altered CYP1A2 and CYP3A activity in rats.

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Do not use if

Internal heat with yin deficiency and profuse sweating (TCM)

Side effects

Gastric irritation (attributed to volatile oil; processing is used to reduce it)

Toxicity

In rats and mice an ethanol extract up to 5,000 mg/kg caused no significant systemic toxicity beyond gastric irritation and mild sedation. Atractylodin was embryotoxic in zebrafish. Phase I in 48 healthy volunteers found the capsule well tolerated.

In the healing traditions

Traditional Chinese Medicine
Cang zhu (Atractylodis Rhizoma)
Dries dampness and strengthens the spleen; also improves vision. Historically used for night blindness, stomach pain and influenza. Its 'dryness' is said to consume yin fluids, so it is avoided in internal heat with yin deficiency and profuse sweating; stir-frying, bran-frying and rice-water processing are used to reduce dryness or redirect its action.
Shennong Bencao Jing (recorded as 'zhu', not yet split from bai zhu); Bencao Yanyi (Song dynasty) first distinguished cang zhu from bai zhu; Chinese Pharmacopoeia 2020
Kampo
Sojutsu
A fundamental ingredient of Kampo formulas such as Juzen-taiho-to and Saireito, used as a diuretic and gastric tonic.
Southeast Asian (Jamu, Thai, Philippine…)
Khod-kha-mao
Thai traditional medicine uses the rhizome mainly for fever, common colds and non-infectious gastrointestinal distress.

Active compounds

atractylodin: polyacetylene; main marker compound; embryotoxic in zebrafish; low systemic exposure in humans
β-eudesmol: sesquiterpene of the volatile oil; metabolised by and inhibits CYP2C19 and CYP3A4 in vitro
hinesol: sesquiterpenoid; reduced inflammation in a DSS-induced colitis model

History

The Shennong Bencao Jing (Eastern Han, 25–220 CE) recorded a single top-grade herb 'zhu'; later authors split it into chizhu (later cang zhu), with slender leaves and bitter rhizomes suited to decoctions, and bai zhu, with large leaves and sweet rhizomes for pills. The Song-dynasty Bencao Yanyi first set out their different uses. Rhizomes from the Maoshan region of Jiangsu are prized as the geo-authentic source.

Sources

Reference, not prescription. Nothing here is medical advice. Herbs can interact with medicines and be dangerous in pregnancy; tell your doctor or pharmacist about anything you take.