Xiao Tong Cao
StarStachyurus himalaicus Hook.f. et Thoms.
Traditionally used for
- Cough & breathing
- Urinary & fluids
☯ TCM Properties
Clears Heat and Promotes Urination; Promotes Lactation; Drains Dampness
Traditional Chinese Uses
Xiao Tong Cao (stachyurus stem or small ricepaperplant pith) is a cool herb used to promote urination and clear Heat from the Heart channel through urination. It is used for painful urination and urinary tract discomfort from Heart or Lung Heat descending to the Bladder. As a mild diuretic, it is gentler than its relative Tong Cao (ricepaperplant pith), and is used for heat-type urinary complaints where a moderate rather than forceful action is appropriate.
Western Herbalism Properties
Relationships
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Botanical Description
Stachyurus himalaicus Hook.f. et Thoms. (Stachyuraceae) is a deciduous shrub or small tree native to the Himalayas, southern China, and northern Indochina, reaching 3-5 m on forest margins and shaded slopes between 1000 and 3000 m. Its slender, reddish-brown branches bear alternate, ovate-lanceolate, finely serrate leaves 7-15 cm long with long-acuminate tips. Before the leaves expand in early spring, pendent, catkin-like racemes 5-10 cm long appear from the previous year's nodes, carrying many small, bell-shaped, pale-yellow flowers. The fruit is a small, fleshy berry. The pith of the stem (Xiao Tong Cao) is harvested and dried for use in traditional Chinese medicine to promote urination and lactation.
Active Constituents
Mucilage
PolysaccharideConcentration: Present in mucilage cells of the stem pith; not quantified
The mucilage cells of the pith are the pharmacopoeial microscopic identity feature that separates Xiao Tong Cao from Tong Cao, whose Tetrapanax pith carries calcium oxalate cluster crystals and no mucilage cells. They also account for the slightly sticky mouthfeel on chewing that is used as a bench-side check. No pharmacological role has been demonstrated for the mucilage.
⚠ Drug Interactions
Tong Cao (Tetrapanax papyrifer pith, Medulla Tetrapanacis)
Xiao Tong Cao and Tong Cao are separate Chinese Pharmacopoeia monographs with the same traditional indications, both being white, light, spongy stem pith, and Xiao Tong Cao is the commonest substitute supplied against orders for Tong Cao. The plants are unrelated: Stachyuraceae or Helwingiaceae against Araliaceae. They are told apart by pith diameter, by the silvery lustre and ladder-like internal membranes of genuine Tetrapanax pith, and microscopically by mucilage cells in Xiao Tong Cao against calcium oxalate cluster crystals in Tong Cao. Nothing isolated from Stachyurus corresponds chemically to the steroids and oleanane triterpenes reported from Tetrapanax pith.
Clinical note: Order by botanical source rather than by the pinyin name, and check the pieces. Narrow-bore pith that turns slightly sticky when chewed is Xiao Tong Cao. Because so little pharmacology exists for either drug, substitution cannot be detected by clinical effect, only by identification.
Helwingia japonica (Thunb.) F. Dietr. pith, the co-official source of Xiao Tong Cao
The Chinese Pharmacopoeia accepts Stachyurus himalaicus, Stachyurus chinensis and Helwingia japonica as sources of Xiao Tong Cao, so material dispensed under this name may come from either Stachyuraceae or Helwingiaceae. The two families are not close, and Helwingia has a separate and larger phytochemical literature of its own. Any chemistry or pharmacology attributed to Xiao Tong Cao must therefore be traced to a named species before it can be applied to this record.
Clinical note: Not something to act on at the bedside, but a reason to treat any published Xiao Tong Cao finding as belonging to whichever species was actually tested. In practice Helwingia and Stachyurus material is not distinguished on invoices.
Aristolochia manshuriensis (Guan Mu Tong), dispensed against Mu Tong or a classical Tong Cao order
Xiao Tong Cao sits at the small end of a family of Chinese drug names built on tong, meaning to unblock, that also contains Tong Cao and Mu Tong. The classical Tong Cao of the Shen Nong Ben Cao Jing is the drug now called Mu Tong, and Mu Tong has been supplied commercially as Guan Mu Tong, the aristolochic-acid-bearing stem of Aristolochia manshuriensis, which causes aristolochic acid nephropathy and upper tract urothelial carcinoma. Xiao Tong Cao carries no such risk itself, but it circulates in the same commercial name space and is dispensed for the same indications, so an order in this family that is filled by name rather than by botanical source can end in Aristolochia.
Clinical note: Require a botanical identification, not a pinyin name, anywhere in the tong drug family. If Mu Tong appears in a formula alongside or instead of a tong cao drug, confirm it is Akebia or Clematis and not Aristolochia manshuriensis before it is dispensed.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 3–6 g | Daily | — | — | 中国药典 2020 【用法与用量】3～6g。 【性味与归经】甘、淡，寒。归肺、胃经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
Evidence Tier
Limited evidence · 2 studiesRecorded studies by study design, strongest design at the top. This is a study-design tier only, not a GRADE rating: it does not weigh risk of bias, consistency or precision.
Systematic review / meta-analysis
0
Randomized controlled trial
0
Other clinical trial
0
Observational / case report
0
In vitro / animal
2
0 verified · 2 unverified
Other / unclassified
0
Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description
Clinical Studies
Triterpenes from Stachyurus himalaicus var. himalaicus Hook. f. et Thoms. ex Benth
Isolated four triterpenes, including one new naturally occurring oleanane-type triterpene, and tested them for cytotoxicity against the human HeLa cell line. The material was leaves and twigs of Stachyurus himalaicus var. himalaicus, not the stem pith that constitutes the drug Medulla Stachyuri, so this chemistry cannot be attributed to Xiao Tong Cao as dispensed.
Flavonoids from leaves and twigs of Stachyurus himalaicus VAR. himalaicus
Reports flavonoids from leaves and twigs of the same variety. As with the triterpene work, the plant part is not the pith, so it describes the plant rather than the drug. Together these two papers constitute essentially the entire phytochemical record for the species, and neither touches the medicinal part.
Historical Texts
Chinese Pharmacopoeia
Modern, current editionsReferences
- Chen Y, Li R, Wang S, Xiong S, Huang Y. The complete chloroplast genome of Stachyurus himalaicus . Mitochondrial DNA Part B (2025) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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