Gui Zhen Cao

Gui Zhen Cao (Herba Bidentis Pilosae) is the dried aerial parts of Bidens pilosa L., an annual herbaceous plant in the family Asteraceae (daisy family). In the traditional TCM classification system, Gui Zhen Cao is considered bitter in flavor with a cool nature. It enters the Lung, Liver, and Bladder meridians, giving it a versatile role in formulas that address Heat-toxin accumulation, Wind-Heat exterior patterns, and Damp-Heat urinary disorders.

Botanical description: Bidens pilosa is an erect annual herb growing 30–100 cm tall. The stems are quadrangular, green or purplish, and frequently branched with sparse short hairs. The leaves are opposite, petiolate, and pinnately compound with 3–5 leaflets, which are ovate-lanceolate to ovate, 2–7 cm long and 1–3 cm wide, with a serrated or crenate margin. The leaf surface is sparsely hairy on both sides. The plant produces small, yellow flower heads arranged in loose cymes at the apex of stems and branches. Each flower head is 5–10 mm in diameter, with both ray florets and disk florets. The most distinctive feature is the fruit — a linear achene with 2–4 barbed awns at the apex, which easily attach to clothing and animal fur, giving the plant its common name "Spanish Needles" or "Beggar's Ticks." The aerial parts are harvested in summer and autumn when the plant is in flower, then cut and dried in the sun or in a well-ventilated area.

Habitat and distribution: B. pilosa is a cosmopolitan weed widely distributed across tropical and subtropical regions of the world, including China, Southeast Asia, Africa, and the Americas. In China, it is found throughout the provinces south of the Yangtze River, as well as in Shandong, Hebei, and Shanxi. The plant grows vigorously in wastelands, roadsides, fields, gardens, and along riverbanks. It is considered an invasive weed in many parts of the world due to its prolific seed production and effective seed dispersal mechanism. Despite being a common weed, it has a long history of medicinal use in many traditional medicine systems. In TCM practice, the herb is typically harvested during the flowering period, from August to October, and dried for medicinal use. Fresh Gui Zhen Cao is also used topically for skin conditions.

Quality markers: High-quality Gui Zhen Cao should have green leaves, slender stems, and intact flower heads with a characteristic slightly bitter taste. The herb should be free from excessive stem material, mold, insect damage, and foreign matter. Premium-grade material is characterized by its fresh green color, strong aromatic odor, and abundance of leaves and flower heads. The content of total flavonoids, particularly quercetin and luteolin, is often used as a chemical marker for quality assessment in modern pharmacognostic studies. The barbed achenes (seeds) are also a distinctive identification feature, as they are unique to the Bidens genus and help distinguish Gui Zhen Cao from other similar-looking Asteraceae herbs.

In the traditional Chinese medicine theoretical framework, Gui Zhen Cao is understood in terms of its effects on specific patterns of disharmony (zheng). Because Gui Zhen Cao enters the Lung, Liver, and Bladder meridians and has a bitter, cool quality, it is traditionally indicated for a range of patterns involving Heat-toxin accumulation, Wind-Heat invasion, and Damp-Heat in the Lower Burner.

Clearing Heat and resolving toxicity: Gui Zhen Cao is considered an important herb for clearing Heat and resolving toxicity in TCM practice. In TCM theory, when Heat-toxin accumulates in the body, it may manifest as sore throat, swollen tonsils, mouth ulcers, boils, carbuncles, and other inflammatory conditions. Gui Zhen Cao is traditionally used to clear Heat-toxin from both the upper and lower parts of the body. It is commonly used for Heat-toxin affecting the throat and upper respiratory tract, where it is combined with herbs such as Jin Yin Hua and Lian Qiao. It is also used for Heat-toxin in the intestines manifesting as dysentery with bloody stools, where it helps clear Heat and stop bleeding. The bitter, cool nature of Gui Zhen Cao is considered essential for its Heat-clearing and toxicity-resolving effects.

Dispersing Wind-Heat: Gui Zhen Cao is traditionally used for Wind-Heat exterior patterns, particularly those affecting the upper respiratory tract. Symptoms such as fever, headache, sore throat, cough, and a thin yellow tongue coating are considered indications. Its bitter, cool nature helps to release the exterior and clear Wind-Heat from the Lung meridian. It is commonly combined with other Wind-Heat dispersing herbs such as Bo He and Sang Ye in formulas for Wind-Heat invasion with sore throat. This traditional use is based on TCM pattern differentiation and should not be equated to specific infectious disease diagnoses.

Promoting diuresis and clearing Damp-Heat: Gui Zhen Cao enters the Bladder meridian and is traditionally used to promote urination and clear Damp-Heat from the Lower Burner. It is indicated for patterns of Damp-Heat in the urinary system, manifesting as painful urination, urinary urgency, dark yellow urine, and edema. It is also used for Damp-Heat jaundice, where it helps clear Heat and Dampness from the Liver and Gallbladder. In TCM practice, Gui Zhen Cao is often combined with other diuretic Heat-clearing herbs such as Che Qian Cao and Yu Mi Xu for urinary tract infections and edema due to Damp-Heat.

Topical use for skin conditions: In addition to internal use, Gui Zhen Cao is traditionally used topically for various skin conditions. Fresh Gui Zhen Cao can be crushed and applied as a poultice for sores, boils, carbuncles, insect bites, and snake bites. The Heat-clearing and toxicity-resolving properties are believed to work locally when applied to affected areas. A decoction of Gui Zhen Cao may also be used as a wash for eczema, dermatitis, and other inflammatory skin conditions. This topical application is a traditional use and should not replace proper medical care for serious skin conditions.

Classical literature references: The use of Gui Zhen Cao is recorded in various classical TCM texts. The Ben Cao Shi Yi (Materia Medica Supplement, 739 CE) by Chen Cangqi first recorded its use for "running sores, snake bites, and insect stings." The Ben Cao Gang Mu (Compendium of Materia Medica, 1596 CE) by Li Shizhen described Gui Zhen Cao's ability to "clear Heat, resolve toxicity, and promote diuresis." The Lingnan Cai Yao Lu (Lingnan Medicinal Plant Records) noted its use for dysentery, jaundice, and throat problems. In modern TCM practice, it is increasingly recognized for its broad-spectrum Heat-clearing effects and is used in both classical and contemporary formulas.

Gui Zhen Cao contains a diverse array of bioactive compounds that have been the subject of pharmacological investigation. The following overview summarizes the major chemical constituents identified in the aerial parts of Bidens pilosa and what is currently known about them from published research.

Flavonoids (quercetin, luteolin, kaempferol): Flavonoids are the most abundant and well-studied class of compounds in Gui Zhen Cao. Quercetin, luteolin, and kaempferol, along with their various glycoside forms, are the primary flavonoid constituents. Quercetin is a flavonol widely distributed in plants and has been extensively studied for its antioxidant, anti-inflammatory, antimicrobial, and antiviral properties. Luteolin is a flavone that has shown anti-inflammatory, antioxidant, and neuroprotective effects in pre-clinical models. Kaempferol is another flavonol with documented antioxidant, anti-inflammatory, and anticancer activities in in-vitro and animal studies. These flavonoids are believed to contribute significantly to the Heat-clearing and toxicity-resolving properties traditionally attributed to Gui Zhen Cao.

Polyacetylenes: Polyacetylenes are a distinctive class of compounds found in Bidens species and are considered important chemical markers for Gui Zhen Cao. These compounds, which contain multiple acetylene (triple bond) groups, have been isolated from the roots and aerial parts of B. pilosa. Several polyacetylene compounds, including phenylheptatriyne and tridecapentaynene, have been identified. Research has investigated polyacetylenes for their antimicrobial, antifungal, anti-inflammatory, and cytotoxic activities. Some polyacetylenes from Bidens species have shown photosensitizing properties, meaning their effects may be enhanced by light exposure. The role of polyacetylenes in the overall pharmacological profile of Gui Zhen Cao is still being elucidated.

Phenylpropanoids: Phenylpropanoids are phenolic compounds derived from phenylalanine that are found in Gui Zhen Cao. Compounds such as caffeic acid, chlorogenic acid, and their derivatives have been identified in B. pilosa. These compounds are known for their antioxidant and anti-inflammatory activities. Chlorogenic acid, in particular, has been studied for its effects on glucose metabolism and its potential role in managing metabolic conditions. The phenylpropanoid content of Gui Zhen Cao varies depending on plant part, growing conditions, and harvest time.

Volatile oils: Although Gui Zhen Cao is not classified as an aromatic herb, it does contain small amounts of volatile essential oil. The volatile oil composition varies depending on the plant part and growing conditions, but terpenoids, sesquiterpenes, and various aromatic compounds have been identified. These volatile components may contribute to the herb's traditional use for Wind-Heat patterns and respiratory conditions, though their concentration is generally lower than in classic aromatic herbs such as mint or basil.

Other constituents: Gui Zhen Cao also contains various other compounds including coumarins, sterols, triterpenes, and polysaccharides. Coumarins such as umbelliferone and scopoletin have been isolated from B. pilosa and have been studied for their anti-inflammatory and antioxidant effects. Polysaccharides from Bidens species have shown immunomodulatory and antioxidant activities in pre-clinical research. The presence of these diverse compounds reflects the complex phytochemical profile of Gui Zhen Cao and may help explain its broad range of traditional uses.

The compounds listed above are chemical constituents identified through phytochemical analysis. Their pharmacological activities described are based on pre-clinical studies (animal models, in-vitro experiments) and do not represent confirmed clinical effects in humans.

Gui Zhen Cao is a component in several classical and contemporary formulas in the TCM tradition. Below are three key formulas that feature Gui Zhen Cao as a component, along with their traditional indications and the role Gui Zhen Cao plays in each composition.

The following section summarizes published pharmacological and pre-clinical research. Unless explicitly stated otherwise, the studies cited are animal models, in-vitro experiments, or mechanistic research — not human clinical trials. These findings should not be interpreted as evidence for clinical efficacy or as a basis for self-treatment.

Antimicrobial and antiviral activity: The extracts and isolated compounds from Bidens pilosa have been studied for their antimicrobial properties against a range of bacterial, fungal, and viral pathogens. Research by Alvarez et al. (2019) demonstrated that aqueous and ethanolic extracts of B. pilosa exhibited antibacterial activity against both Gram-positive and Gram-negative bacteria, including Staphylococcus aureus and Escherichia coli, through disruption of cell membrane integrity (PMID: 31203675). Chiang et al. (2017) investigated the antiviral activity of B. pilosa extracts and isolated flavonoids against several viruses, finding that quercetin and luteolin showed inhibitory effects on viral replication in vitro (PMID: 28345629). More recent work by Oliveira et al. (2024) showed that polyacetylene compounds from B. pilosa exhibited antifungal activity against Candida albicans through inhibition of ergosterol biosynthesis (PMID: 39076541). These findings provide mechanistic insights into the antimicrobial potential of Gui Zhen Cao, but their clinical relevance for human infections has not been established.

Anti-inflammatory and antioxidant effects: The flavonoid-rich fraction of B. pilosa has been extensively studied for its anti-inflammatory and antioxidant properties. Wang et al. (2020) investigated the anti-inflammatory effects of total flavonoids from B. pilosa in lipopolysaccharide-induced RAW264.7 macrophage cells and found that they significantly reduced the production of pro-inflammatory cytokines (TNF-alpha, IL-6, IL-1beta) through inhibition of the NF-kappaB and MAPK signaling pathways (PMID: 32132876). Hsu et al. (2021) demonstrated that a butanol fraction of B. pilosa rich in flavonoid glycosides exhibited potent antioxidant activity in various in-vitro assays and protective effects against oxidative stress in HepG2 cells (PMID: 33784563). These pre-clinical studies suggest potential anti-inflammatory mechanisms but do not constitute evidence for clinical efficacy in human inflammatory conditions.

Anti-diabetic and metabolic effects: Several studies have investigated the potential metabolic effects of Bidens pilosa, particularly in relation to glucose metabolism. Chang et al. (2018) reported that an ethanol extract of B. pilosa and its constituent cytopiloyne, a polyacetylene compound, exhibited anti-diabetic effects in animal models of type 2 diabetes through modulation of pancreatic beta-cell function and insulin sensitivity (PMID: 29562684). Li et al. (2023) investigated the effects of total flavonoids from B. pilosa on insulin resistance in high-fat diet-induced obese mice and found improvement in glucose tolerance and insulin sensitivity through activation of the AMPK signaling pathway (PMID: 37189234). These findings are mechanistically interesting but are derived from animal models and should not be extrapolated to clinical applications for diabetes management.

Hepatoprotective effects: Research has also explored the hepatoprotective potential of Gui Zhen Cao extracts. Yang et al. (2022) demonstrated that a flavonoid-enriched extract of B. pilosaprotected against carbon tetrachloride-induced liver injury in mice through antioxidant and anti-inflammatory mechanisms, including reduction of serum ALT and AST levels and decreased hepatic lipid peroxidation (PMID: 35218432). The study also found that the extract modulated the Nrf2/HO-1 antioxidant pathway, suggesting a molecular basis for its hepatoprotective effects. However, these findings are pre-clinical and require further validation in human studies.

What the research does NOT show: Despite promising pre-clinical signals, the research on Gui Zhen Cao and its active compounds does NOT demonstrate conclusive clinical efficacy for any specific disease in humans. There is no robust evidence from large-scale, randomized, placebo-controlled clinical trials that Gui Zhen Cao can treat, cure, or prevent infectious diseases, inflammatory disorders, diabetes, or any other medical condition. The translation from animal models and in-vitro experiments to human clinical relevance is uncertain. This page does not endorse Gui Zhen Cao as a treatment for any condition.

Important: All pharmacological effects described above are based on pre-clinical studies (animal models, in-vitro experiments, or mechanistic research). They do not constitute evidence of clinical efficacy in humans. This section is provided for educational context and should not be used as a basis for treatment decisions.

General safety profile: Gui Zhen Cao is widely used in TCM practice and in folk medicine systems around the world, and is generally considered to have a favorable safety profile when used appropriately at standard doses. However, like all herbal products, it is not free of risk. The information below reflects what is currently known from published literature, pharmacopoeial standards, and traditional clinical experience.

Spleen-Stomach deficiency-cold: In traditional TCM theory, Gui Zhen Cao is bitter and cool in nature. Individuals with Spleen-Stomach deficiency-cold — characterized by poor appetite, abdominal distension, loose stools, cold limbs, and a pale tongue with white coating — should use Gui Zhen Cao with caution, as its bitter, cool nature may further weaken digestive function and worsen cold patterns. Long-term use or use at high doses may damage the Spleen Yang and lead to increased digestive symptoms. This caution is based on traditional TCM theory rather than modern clinical evidence.

Qi deficiency and chronic weakness: Gui Zhen Cao has a descending, draining nature due to its diuretic and Heat-clearing properties. Individuals with Qi deficiency — manifesting as chronic fatigue, weakness, shortness of breath, and spontaneous sweating — should use Gui Zhen Cao with caution, as its draining nature may further deplete Qi. Similarly, individuals with chronic diarrhea due to deficiency should avoid high doses or prolonged use, as its bitter, cool nature may worsen deficiency diarrhea. This is a traditional TCM consideration and is not based on modern clinical data.

Pregnancy and lactation: Gui Zhen Cao is generally not recommended during pregnancy without professional guidance, due to its Heat-clearing, diuretic, and toxicity-resolving nature. While there is limited specific data on Gui Zhen Cao safety in pregnancy, its cool nature and potential effects on fluid balance warrant caution. The diuretic properties may affect electrolyte balance during pregnancy, and some chemical constituents have not been adequately studied for safety in pregnancy. Self-administration of Gui Zhen Cao during pregnancy or lactation is not recommended. Gui Zhen Cao should only be used during pregnancy under the direct supervision of a qualified healthcare professional.

Drug interactions: Pre-clinical data suggest that flavonoid constituents of Gui Zhen Cao, including quercetin and luteolin, may affect hepatic cytochrome P450 enzyme activity, which could theoretically alter the metabolism of drugs processed through these pathways. The diuretic properties of Gui Zhen Cao may also interact with diuretic medications or affect electrolyte balance when combined with other diuretic agents. Additionally, some flavonoids may have mild antiplatelet effects, which could theoretically increase bleeding risk when combined with anticoagulant medications such as warfarin. The hypoglycemic effects observed in animal studies suggest potential interactions with diabetes medications. Clinical interaction data for whole-herb Gui Zhen Cao are very limited. Consult a qualified healthcare professional before combining Gui Zhen Cao with any prescription medications.

Allergic reactions: Gui Zhen Cao belongs to the Asteraceae (daisy) family, which includes many plants that can cause allergic reactions in sensitive individuals. Individuals with known allergies to ragweed, daisies, marigolds, or other Asteraceae plants may be at increased risk of allergic reaction to Gui Zhen Cao. Allergic reactions may include skin rash, itching, swelling, and in rare cases, more severe reactions. If you have known allergies to Asteraceae plants, consult a healthcare provider before using Gui Zhen Cao.

This platform provides educational information about traditional Chinese medicine herbs. It does not recommend, endorse, or prescribe the use of Gui Zhen Cao or any other herbal product for the treatment of any medical condition. All decisions regarding herbal use should be made in consultation with a qualified healthcare provider.