Traditionally used for
- Cough & breathing
- Colds & fever
- Bowel health
- Urinary & fluids
- Skin
☯ TCM Properties
Clears Heat, promotes diuresis, disperses Stagnation and resolves toxicity
Traditional Chinese Uses
Lu Cao is the whole herb of Humulus scandens (Cannabaceae), the Asian or Japanese hop, a barbed annual climber. Sweet and bitter with a cold nature, it clears Heat, promotes urination, disperses stagnation and resolves toxicity. Documented since the Tang-dynasty Tang Ben Cao, it is used for lung-heat cough and low-grade tidal fever (including patterns historically treated as consumptive or malarial fever), damp-heat urinary dribbling and stones, and damp-heat dysentery and diarrhea. Its Heat-clearing, toxin-resolving action is also applied externally, the fresh herb crushed for sores, boils, eczema and snakebite.
It is decocted, or the fresh plant expressed for juice and used as a topical wash or poultice.
Western Herbalism Properties
Relationships
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Botanical Description
Lu Cao is the whole herb of Humulus scandens (Cannabaceae), Asian or Japanese hop, an annual or short-lived perennial climber widespread across East Asia in thickets, hedgerows and waste ground. Stems can reach 3–5 m, are angular and densely armed with retrorse hooked prickles that cling readily to surrounding vegetation and to skin. Leaves are opposite, long-petioled, and palmately five- to seven-lobed with sharply serrate margins; both surfaces are rough with stiff hairs. The species is dioecious: male flowers are small, greenish, in loose terminal panicles, while female flowers form pale green, cone-like pendulous catkins with overlapping ovate bracts that enlarge in fruit. The plant has a distinctive bitter herbaceous odour when bruised.
Active Constituents
Luteolin
FlavoneConcentration: One of the principal flavones of the aerial parts; content varies with harvest and processing and is not standardised.
The compound most often credited with the antibacterial action behind the traditional use for dysentery and enteritis. Isolated luteolin from Humulus scandens has a minimum inhibitory concentration of 500 micrograms/mL against standard Escherichia coli strains and kills by damaging the cell wall and membrane, with confirmed disruption of membrane-structure and phenylalanine-metabolism proteins.
Chrysosplenetin and casticin
Polymethoxylated flavonolConcentration: Isolated from the stems and leaves; minor constituents, unquantified.
Methoxylated flavonols recovered from the stems and leaves. They belong to the flavonoid fraction that carries the immunosuppressive and anti-inflammatory activity reported for the plant, though neither has been tested individually in this species.
Citrunohin A
DihydrochalconeConcentration: A new compound described from the stems and leaves; trace level.
A dihydrochalcone first characterised from this species in 2023, alongside twelve other compounds obtained from Humulus scandens for the first time, including neoechinulin A, inonotusic acid, arteannuin B and eicosanyl trans-p-coumarate. It has no pharmacology of its own yet and is listed as a chemotaxonomic marker.
Xanthotoxol
FuranocoumarinConcentration: Isolated from the stems and leaves; content not quantified.
A linear furanocoumarin recovered from the aerial parts. Furanocoumarins as a class photosensitise skin and can inhibit intestinal CYP3A4, so its presence is worth recording even though its amount here is unknown and its systemic relevance untested.
beta-Sitosterol
PhytosterolConcentration: Identified among the principal bioactive compounds of the herb in network-pharmacology profiling; unquantified.
A common anti-inflammatory phytosterol, one of the 19 distinctive bioactive compounds mapped in Humulus scandens, whose predicted targets converge on PI3K-Akt, TNF, MAPK, IL-17, JAK-STAT and HIF-1 signalling.
Hum j 1 (pollen allergen)
Pollen protein allergenConcentration: Confined to the pollen of the flowering plant, not to the dried medicinal herb.
Not a therapeutic constituent but a route-specific hazard. Humulus scandens pollen is a leading cause of autumn pollinosis across East Asia, and Hum j 1 has been characterised as its major allergen; recombinant profilins from the species are also allergenic. Air pollution has been shown to modify the allergenicity of pollen collected from different areas. This matters for practitioners who handle or harvest the fresh plant rather than for patients taking the decoction.
⚠ Drug Interactions
Immunosuppressants and immunomodulators (e.g. ciclosporin, tacrolimus, azathioprine, systemic corticosteroids)
The active fraction of Humulus scandens is directly immunosuppressive. In vitro it inhibited splenocyte proliferation driven by concanavalin A, LPS and mixed lymphocyte reaction, suppressed proliferation and interferon-gamma production by anti-CD3/anti-CD28-stimulated T cells, and blocked differentiation of interferon-gamma-producing Th1 cells; in vivo it suppressed ovalbumin-induced T cell responses and CD4-mediated delayed-type hypersensitivity. Mechanistically it impeded Erk1/2 and p38 activation in primary T cells. This is a defined pharmacological action of the herb, not an incidental finding, and it points in the same direction as any pharmaceutical immunosuppressant.
Clinical note: Avoid layering Lu Cao onto ciclosporin, tacrolimus or high-dose corticosteroids without a reason, and avoid it entirely in transplant recipients whose regimen is being titrated. Also consider stopping it around vaccination and during checkpoint-inhibitor therapy, where suppressing Th1 responses is counterproductive.
Photosensitising drugs (e.g. tetracyclines, fluoroquinolones, amiodarone, methoxsalen, voriconazole)
Xanthotoxol, a linear furanocoumarin of the same family as the psoralens, was isolated from the stems and leaves of Humulus scandens. Furanocoumarins intercalate DNA and cross-link on UVA exposure, which is the basis of psoralen phototoxicity. No content figure exists for xanthotoxol in this herb and no phototoxic reaction has been reported from it, so this is inference from chemistry, not from clinical experience.
Clinical note: Worth mentioning only where a patient is already on a strongly photosensitising drug or undergoing phototherapy. Handling the fresh plant carries a separate and better-established problem: the stems bear recurved prickles that abrade skin mechanically.
Humulus lupulus (common hops), the other medicinal species in the genus
Humulus scandens is also called Humulus japonicus and, in English, Japanese hop, which invites confusion with common hops. The drugs are not comparable. Lu Cao is the whole aerial part of Humulus scandens, used to clear heat, promote urination and resolve toxicity; hops is the strobile of Humulus lupulus, whose activity rests on the lupulin-gland bitter acids and prenylflavonoids that give it sedative and oestrogenic effects and its own set of interactions. Humulus lupulus is also a documented allergen with pollen cross-reactivity. No case series of the two being interchanged has been published, so this is recorded as a naming hazard rather than a documented adulteration.
Clinical note: Order by binomial. If a supplier ships strobiles rather than cut stems and leaves, it is the wrong species. This matters most in Western dispensaries, where 'hops' is the familiar item and Humulus scandens is not.
Evidence Tier
Moderate evidence · 4 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
4
2 verified · 2 unverified
Show 4 studies
- Humulus scandens Exhibits Immunosuppressive Effects in Vitro and in Vivo by Suppressing CD4+ T Cell Activation
- In vitro and in vivo evaluation of antibacterial activity and mechanism of luteolin from Humulus scandens against Escherichia coli from chicken
- Characterization of the clinical relevance and hypoallergenic peptides of the newly evidenced major allergen Hum j 1
- Dietary of different forms of Humulus scandens on growth performance and intestinal bacterial communities in piglets
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
Humulus scandens Exhibits Immunosuppressive Effects in Vitro and in Vivo by Suppressing CD4+ T Cell Activation
The major active fraction of Humulus scandens was prepared and tested in cell and mouse models. It inhibited splenocyte proliferation induced by concanavalin A, LPS and mixed lymphocyte reaction, suppressed proliferation and interferon-gamma production from anti-CD3/anti-CD28-stimulated T cells, and suppressed Th1 differentiation. In vivo it suppressed ovalbumin-immunisation-induced T cell reaction and CD4-mediated delayed-type hypersensitivity. Western blotting showed impaired Erk1/2 and p38 activation in primary T cells. The paper notes the herb's traditional Chinese use for tuberculosis, dysentery and chronic colitis.
In vitro and in vivo evaluation of antibacterial activity and mechanism of luteolin from Humulus scandens against Escherichia coli from chicken
Network pharmacology across 19 bioactive compounds of Humulus scandens selected luteolin, which had an MIC of 500 micrograms/mL against standard Escherichia coli. Electron and confocal microscopy showed damage to cell wall and membrane; proteomics showed altered membrane-structure and phenylalanine-metabolism proteins. In SPF chickens infected with clinical E. coli isolates, luteolin limited the fall in growth performance, prevented organ pathology, suppressed inflammation and improved immune and antioxidant measures.
Characterization of the clinical relevance and hypoallergenic peptides of the newly evidenced major allergen Hum j 1
Characterises Hum j 1 as a major allergen of Humulus pollen and maps hypoallergenic peptides from it for potential immunotherapy. Establishes the molecular basis of the autumn pollinosis that Humulus scandens causes across East Asia, which is the main safety consideration attaching to the living plant rather than to the dried herb.
Dietary of different forms of Humulus scandens on growth performance and intestinal bacterial communities in piglets
Feeding trial comparing forms of Humulus scandens in piglets, measuring growth performance and intestinal bacterial community composition. Part of the body of work testing the herb as an antibiotic replacement in livestock, which is currently where most of the in vivo evidence for this species sits. No human dosing data exist.
Historical Texts
Ming Yi Bie Lu
Han to Southern and Northern dynasties, roughly 220-500 CEXin Xiu Ben Cao
Tang dynasty, 659 CEReferences
- Dang DX, Li D, Xu SQ, He F, Xia X, Xu S. Pharmacological properties of Humulus scandens: Insights from the TCMSP database and existing understanding . Pharmacological Research - Modern Chinese Medicine (2024) [DOI]
- Dang X, Wang H, Li SH, Fan XY, Li D. Application potential of Humulus Scandens in livestock husbandry . Journal of Animal Physiology and Animal Nutrition (2023) [DOI]
- Wu YN, Sun B, Wang JY, Wang DZ, Song M, Zhang XQ. [A new dihydrochalcone from Humulus scandens]. . Zhongguo Zhong Yao Za Zhi (China Journal of Chinese Materia Medica) (2023) [DOI]
- Jung CG, Park HS. Emerging Hop Japanese Pollinosis in Asia . Current Protein and Peptide Science (2022) [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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