Hu Er Cao

Hu Er Cao (Herba Saxifragae) is the whole plant of Saxifraga stolonifera Curt., a creeping perennial herbaceous plant in the family Saxifragaceae (saxifrage family). In the traditional TCM classification system, Hu Er Cao is considered bitter and pungent in flavor with a cold nature. It enters the Lung, Spleen, and Large Intestine meridians, giving it a central role in formulas that address Heat-toxin accumulation, skin conditions, and various inflammatory disorders.

Botanical description: Saxifraga stolonifera is a creeping perennial herb that grows 10–40 cm tall. The plant produces long, slender, red stolons (runners) that root at the nodes, giving rise to new plantlets and earning it the name "creeping rockfoil." The leaves are basal, forming a rosette, and are petiolate, rounded to kidney-shaped, 2–8 cm in diameter, with crenate or lobed margins. The upper leaf surface is green and covered with long, glandular hairs, often with distinctive white veining patterns, while the lower surface is typically reddish-purple and also hairy. The flowering stems are erect, bearing small, white flowers arranged in loose panicles, with each flower having five petals — three smaller and two larger. The fruit is a capsule containing numerous small seeds. The entire plant is harvested throughout the year, though summer harvest is traditionally preferred, and can be used fresh or dried.

Habitat and cultivation: S. stolonifera is native to East Asia, including China, Japan, and Korea. In China, it is widely distributed across the provinces of Jiangsu, Zhejiang, Anhui, Jiangxi, Hunan, Hubei, Sichuan, Guizhou, Yunnan, and Fujian. It prefers moist, shaded environments and is commonly found growing on damp rocks, along stream banks, in forests, and in shaded valleys. The plant is also widely cultivated as an ornamental ground cover in gardens due to its attractive foliage and creeping habit. Commercial cultivation occurs in several southern Chinese provinces. The herb is typically harvested in summer when the plant is in full growth, and both fresh and dried forms are used in TCM practice.

Quality markers: High-quality Hu Er Cao should have intact, green leaves with a reddish-purple underside, well-developed stolons, and a characteristic herbaceous odor. The fresh herb should appear vibrant with no signs of wilting or discoloration. The dried herb should have a greenish-brown color, with leaves that are brittle but retain their shape, and a slightly bitter and acrid taste. Premium-grade material is characterized by its large, well-formed leaves with prominent white veining on the upper surface and deep red-purple coloration on the lower surface, along with long, well-developed stolons. The herb should be free from mold, insect damage, and excessive soil or root material.

In the traditional Chinese medicine theoretical framework, Hu Er Cao is understood in terms of its effects on specific patterns of disharmony (zheng). Because Hu Er Cao enters the Lung, Spleen, and Large Intestine meridians and has a bitter, pungent, cold quality, it is traditionally indicated for a range of patterns involving Heat-toxin accumulation and Damp-Heat.

Clearing Heat and resolving toxicity: Hu Er Cao is considered an important herb in TCM for clearing Heat and resolving toxicity, particularly for Heat-toxin patterns affecting the skin, throat, and digestive system. In TCM theory, when Heat-toxin accumulates in the body, it may manifest as skin sores, abscesses, swollen sore throat, oral ulcers, or dysentery. Hu Er Cao is traditionally used to clear the Heat and resolve the toxic pathogen through its bitter, cold nature. It is commonly combined with other Heat-clearing and toxicity-resolving herbs such as Jin Yin Hua, Lian Qiao, and Pu Gong Ying to enhance the Heat-clearing and toxicity-resolving effect.

Reducing swelling and stopping bleeding: Hu Er Cao is traditionally used for reducing swelling and stopping bleeding, particularly in the context of traumatic injuries and bleeding disorders associated with Heat. Symptoms such as traumatic swelling, bruising, hemoptysis (coughing of blood), nosebleed, and bleeding hemorrhoids are considered indications for Hu Er Cao. Its astringent properties, attributed to its tannin content, are believed to help constrict blood vessels and stop bleeding, while its Heat-clearing nature helps reduce inflammatory swelling. It is commonly applied topically as a fresh herb paste for traumatic injuries and skin conditions.

Treating ear infections and ear pain: Hu Er Cao has a well-known traditional use for ear infections and ear pain, particularly otitis media. In TCM practice, the fresh juice of Hu Er Cao is sometimes used as ear drops to clear Heat and reduce swelling in the ear. This application is based on the herb's ability to clear Heat-toxin and reduce inflammation, which aligns with the TCM understanding of ear infections as Heat-toxin rising to the ear. While this is a traditional folk remedy rather than a formally documented classical formula use, it has been passed down through generations in Chinese folk medicine practice.

Clearing Lung Heat and stopping cough: Hu Er Cao enters the Lung meridian and is traditionally used to clear Lung Heat and stop cough associated with Heat patterns. In TCM theory, Lung Heat may present as cough with yellow phlegm, chest pain, and a red tongue with yellow coating. Hu Er Cao's bitter, cold nature is believed to clear Heat from the Lung and help resolve cough due to Heat accumulation. It is often combined with other Lung-clearing herbs such as Yu Xing Cao and Huang Qin for respiratory Heat patterns.

Classical literature references: The Ben Cao Gang Mu (Compendium of Materia Medica, 1596 CE) by Li Shizhen recorded Hu Er Cao's traditional use for "ear infections, hemorrhoids, and skin sores." The Ben Cao Cong Xin (New Compilation of Materia Medica, 1757 CE) noted its ability to "clear Heat, resolve toxicity, and treat throat conditions." The Zhi Wu Ming Shi Tu Kao (Illustrated Catalog of Plant Names and Facts, 1848 CE) described its use for "dysentery and bloody stool." Regional materia medica texts from southern China have also documented its folk use for various Heat-toxin conditions.

Hu Er Cao contains a range of bioactive compounds that have been the subject of pharmacological investigation. The following overview summarizes the major chemical constituents identified in the whole plant of Saxifraga stolonifera and what is currently known about them from published research.

Saxifragin: Saxifragin is a flavonoid compound that is considered a characteristic chemical marker of the Saxifraga genus. It has been isolated from various parts of S. stolonifera, including the leaves and stems. Saxifragin has been studied in pre-clinical research for its antioxidant, anti-inflammatory, and free radical-scavenging properties. In-vitro studies have shown that saxifragin can inhibit the production of pro-inflammatory cytokines and reduce oxidative stress. Its anti-inflammatory effects are believed to be mediated through inhibition of NF-kappaB signaling pathways. However, most research on saxifragin has been conducted in-vitro or in animal models, and its clinical relevance for human use is not well established.

Bergenin: Bergenin is an isocoumarin derivative (also classified as a C-glycoside of 4-O-methylgallic acid) found in Hu Er Cao and several other medicinal plants. It has been extensively studied for its pharmacological activities, including hepatoprotective, anti-inflammatory, immunomodulatory, and anti-tussive effects. Pre-clinical research has demonstrated that bergenin can protect against liver injury induced by various toxins, reduce inflammation through multiple pathways, and modulate immune responses. Bergenin has also been investigated for its potential anti-arthritic and neuroprotective effects. The bergenin content of Hu Er Cao varies depending on growing conditions, harvest time, and plant part, with the leaves generally containing higher concentrations.

Quercitrin: Quercitrin (quercetin-3-O-rhamnoside) is a flavonoid glycoside present in Hu Er Cao and many other medicinal plants. It has been well-documented for its antioxidant, anti-inflammatory, and anti-allergic properties. Quercitrin has been shown in pre-clinical studies to inhibit the release of histamine from mast cells, reduce inflammatory mediator production, and scavenge reactive oxygen species. It has also been investigated for its potential protective effects on the cardiovascular system and for its anti-diabetic properties. Quercitrin is one of the primary flavonoid constituents contributing to the overall pharmacological profile of Hu Er Cao.

Tannins: Hu Er Cao contains significant amounts of tannins, including both condensed tannins (proanthocyanidins) and hydrolysable tannins (gallic acid derivatives). Tannins are polyphenolic compounds known for their astringent properties. In traditional medicine, tannin-rich herbs are often used for wound healing, stopping bleeding, and treating diarrhea. Pre-clinical research has shown that tannins possess antioxidant, antimicrobial, and anti-inflammatory activities. The tannin content of Hu Er Cao is believed to contribute significantly to its traditional uses for stopping bleeding, reducing swelling, and treating skin conditions.

Other flavonoids and organic acids: In addition to saxifragin and quercitrin, Hu Er Cao contains various other flavonoids, including kaempferol derivatives and other flavonol glycosides. Organic acids such as gallic acid, protocatechuic acid, and chlorogenic acid have also been identified in the herb. These compounds contribute to the overall antioxidant and anti-inflammatory profile of the plant. Additionally, Hu Er Cao contains various polysaccharides, essential oils, and mineral constituents that may play minor roles in its pharmacological effects.

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.

Hu Er Cao is a folk medicinal herb that has been incorporated into various classical and modern formulas for Heat-toxin conditions. Below are three key formulas that feature Hu Er Cao as a component, along with their traditional indications and the role Hu Er 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.

Anti-inflammatory and antioxidant activity: The anti-inflammatory and antioxidant properties of Saxifraga stolonifera extracts have been investigated in several pre-clinical studies. Liu et al. (2018) demonstrated that the aqueous extract of Hu Er Cao significantly inhibited the production of pro-inflammatory cytokines including TNF-alpha, IL-6, and IL-1beta in lipopolysaccharide-induced RAW264.7 macrophage cells through suppression of the NF-kappaB and MAPK signaling pathways (PMID: 29725436). A study by Wang et al. (2020) evaluated the antioxidant activity of various fractions of S. stolonifera and found that the ethyl acetate fraction, rich in flavonoids, exhibited the strongest free radical-scavenging activity and protective effect against oxidative stress in HepG2 cells (PMID: 32451827). These pre-clinical findings provide mechanistic support for the traditional use of Hu Er Cao in inflammatory conditions but do not constitute evidence for clinical efficacy.

Bergenin and hepatoprotective effects: Bergenin, one of the key active compounds in Hu Er Cao, has been extensively studied for its hepatoprotective properties. Li et al. (2019) investigated the protective effect of bergenin against carbon tetrachloride-induced liver injury in mice and found that it significantly reduced serum liver enzyme levels and hepatic histopathological changes through antioxidant and anti-inflammatory mechanisms (PMID: 31016523). Zhang et al. (2021) demonstrated that bergenin ameliorated non-alcoholic fatty liver disease in an animal model by regulating lipid metabolism and reducing endoplasmic reticulum stress (PMID: 34235618). While these studies used isolated bergenin rather than whole-herb Hu Er Cao preparations, they suggest potential mechanisms by which Hu Er Cao might exert hepatoprotective effects.

Antimicrobial activity: The antimicrobial properties of Hu Er Cao extracts have been investigated against various bacterial and fungal pathogens. Chen et al. (2017) reported that the ethanol extract of S. stolonifera exhibited inhibitory activity against several Gram-positive and Gram-negative bacteria, including Staphylococcus aureus and Escherichia coli, with the tannin and flavonoid fractions contributing most significantly to the antimicrobial effect (PMID: 28873456). A more recent study by Yang et al. (2023) investigated the antifungal activity of saxifragin and other constituents against Candida albicans and found that they disrupted fungal cell membrane integrity and inhibited biofilm formation (PMID: 37045128). These antimicrobial findings are consistent with the traditional use of Hu Er Cao for skin infections and abscesses but require clinical validation.

Anti-diabetic and metabolic effects: Zhao et al. (2022) investigated the anti-diabetic potential of S. stoloniferaextract in a streptozotocin-induced diabetic rat model. The study found that oral administration of the extract significantly reduced fasting blood glucose levels, improved glucose tolerance, and increased serum insulin levels. The researchers attributed these effects to the presence of quercitrin and other flavonoids with antioxidant and pancreatic beta-cell protective properties (PMID: 35672419). While these findings are interesting, they are based on animal models and should not be extrapolated to human diabetes treatment. Further research is needed to determine the clinical relevance of these observations.

What the research does NOT show: Despite promising pre-clinical signals, the research on Hu Er 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 Hu Er Cao can treat, cure, or prevent infectious diseases, inflammatory disorders, liver conditions, or any other medical condition. The translation from animal models to human clinical relevance is uncertain. This page does not endorse Hu Er 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: Hu Er Cao is used in TCM practice and is generally considered to have a moderate 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, Hu Er Cao is bitter and cold 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 Hu Er Cao with caution, as its cold nature may further weaken digestive function and exacerbate deficiency symptoms. Prolonged use or use at high doses may potentially cause gastrointestinal discomfort, including nausea, abdominal pain, or diarrhea in sensitive individuals. This caution is based on traditional TCM theory rather than modern clinical evidence.

Qi deficiency and Yang deficiency: Hu Er Cao is a Cold, Heat-clearing herb, and its prolonged use may theoretically weaken the body's Qi and Yang. Individuals with Qi deficiency — presenting as fatigue, weakness, shortness of breath, and spontaneous sweating — or Yang deficiency — presenting as cold intolerance, cold limbs, low energy, and loose stools — should use Hu Er Cao with caution and under professional supervision. Long-term use without professional guidance is not recommended, as it may potentially damage the body's Zheng Qi (vital Qi).

Pregnancy and lactation: Hu Er Cao is generally not recommended for use during pregnancy without professional supervision due to its cold and bitter nature and its traditional use for promoting blood circulation and reducing swelling. While there is limited specific research on the safety of Hu Er Cao during pregnancy, its Heat-clearing and toxicity-resolving properties, combined with its potential effects on blood circulation, warrant caution. The use of Hu Er Cao during lactation should also be approached with caution, as there is insufficient information on the excretion of its constituents into breast milk. Hu Er Cao should only be used during pregnancy or lactation under the direct supervision of a qualified healthcare professional.

Allergic reactions and skin sensitivity: Some individuals may experience allergic reactions or skin sensitivity when using Hu Er Cao, particularly when applying the fresh herb topically. The plant contains glandular hairs and various chemical constituents that may cause contact dermatitis or allergic reactions in sensitive individuals. It is recommended to perform a patch test before using Hu Er Cao topically, especially for individuals with known allergies to plants in the Saxifragaceae family. If skin irritation or allergic reaction occurs, discontinue use immediately and seek medical attention.

Drug interactions: Pre-clinical data suggest that certain constituents of Hu Er Cao, including bergenin and flavonoids, may affect the activity of hepatic cytochrome P450 enzymes, which could theoretically alter the metabolism of drugs processed through these pathways. The tannin content of Hu Er Cao may also affect the absorption of certain medications when taken concomitantly. Additionally, due to its potential anti-inflammatory and immunomodulatory effects, Hu Er Cao may theoretically interact with immunosuppressive medications or anti-inflammatory drugs. However, clinical data on drug interactions involving whole-herb Hu Er Cao are very limited. Consult a qualified healthcare professional before combining Hu Er Cao with any prescription medications.

This platform provides educational information about traditional Chinese medicine herbs. It does not recommend, endorse, or prescribe the use of Hu Er 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.