Yi Zhi Hao

Yi Zhi Hao (Alpine Yarrow Herb) is the dried aerial part of Achillea alpina L., an herbaceous perennial plant in the family Asteraceae. In the traditional TCM classification system, Yi Zhi Hao is considered pungent and bitter in flavor with a warm nature. It enters the Liver, Spleen, and Gallbladder meridians, giving it a traditional role in formulas that address Wind-Damp Bi syndrome, pain, and Qi stagnation.

Botanical description: Achillea alpina is a perennial herb growing 30–80 cm tall, with erect, branched, and ribbed stems. The leaves are alternate, sessile, linear-oblong to lanceolate in outline, and pinnately divided into numerous fine, linear segments, giving them a feathery appearance. The plant produces numerous small flower heads (capitula) arranged in dense, flat-topped corymbs. Each flower head has white ray florets (4–6) and a central disc of whitish-yellow tubular florets. The flowering period is typically July–September. The fruit is a small, compressed achene without a pappus.

Habitat and distribution: A. alpina is native to East Asia, including northern and southwestern China (Yunnan, Sichuan, Tibet), Korea, Japan, Mongolia, and Siberia. The plant prefers sunny or partially shaded habitats, including grassy slopes, forest margins, stream banks, and roadsides, at elevations of 1,500–3,500 meters. It is well-adapted to cool, temperate climates and is relatively drought-tolerant once established. In China, the primary source regions for medicinal use are Yunnan, Sichuan, and the Tibetan plateau.

Harvesting and preparation: The aerial parts of Yi Zhi Hao are harvested in summer and autumn when the plant is in full bloom. The stems and leaves are collected, cleaned of soil and foreign matter, and dried in the shade or in a well-ventilated area. The dried material is cut into small sections for decoction or further processing. In folk medicine, the fresh herb is sometimes used directly for topical applications. Unlike many officially listed TCM herbs, Yi Zhi Hao does not have a standardized monograph in the Chinese Pharmacopoeia, and quality control is primarily based on regional empirical standards.

In the traditional Chinese medicine theoretical framework, Yi Zhi Hao is understood in terms of its effects on specific patterns of disharmony (zheng). Because Yi Zhi Hao enters the Liver, Spleen, and Gallbladder meridians and has a pungent, bitter, and warm quality, it is traditionally indicated for a range of patterns involving Wind-Dampness, pain, and Qi stagnation.

Dispelling Wind-Damp and stopping pain: Yi Zhi Hao is considered one of the folk herbs for Wind-Damp Bi syndrome, a TCM pattern characterized by painful, heavy, and stiff joints that may be aggravated by cold and damp weather. In folk medicine, it is traditionally used for rheumatic pain, joint swelling, and lower back pain. Its warm, pungent nature is believed to disperse Wind-Cold-Damp pathogens from the channels and collaterals. It is commonly combined with Fang Feng and Qiang Huo in formulas for Wind-Damp disorders.

Resolving toxicity and reducing swelling: In folk medicine, Yi Zhi Hao is traditionally applied externally for poisonous snakebites, insect stings, carbuncles, and skin infections. The fresh herb is crushed and applied as a poultice to the affected area. This use is based on the herb's traditional classification as having toxin-resolving and swelling-reducing properties. Internally, it has been used in decoction form for conditions involving toxic accumulation, such as skin infections and abscesses.

Regulating Qi and harmonizing the Middle: Yi Zhi Hao enters the Spleen meridian and is traditionally used to regulate Qi and harmonize the Middle Burner. In folk medicine, it is used for abdominal distension, epigastric pain, and digestive discomfort associated with Qi stagnation. It may be combined with Chen Pi to strengthen its Qi-regulating and digestive-harmonizing effects. This use is particularly common in the folk traditions of Yunnan and Sichuan.

Headache and Wind disorders: Yi Zhi Hao is traditionally used for headaches, particularly those classified in TCM as Wind-type headaches (manifesting as migrating, distending pain in the head). It is believed to disperse exterior Wind and relieve headache by entering the Liver and Gallbladder meridians. In folk practice, it has been used for both Wind-Cold and Wind-Heat presentations, depending on the combination of herbs used.

Folk documentation: Yi Zhi Hao is documented in several regional Chinese herbal compilations, including the Yunnan Chinese Materia Medica (Dian Nan Ben Cao) and the Sichuan Chinese Materia Medica. These sources describe its traditional uses for dispelling Wind, relieving pain, resolving toxicity, and awakening the Spleen. It is considered a characteristic folk herb of the southwestern ethnic minorities, particularly in Yi, Tibetan, and Naxi traditional medicine systems.

Yi Zhi Hao contains a range of bioactive compounds that have been the subject of phytochemical and pharmacological investigation. The following overview summarizes the major chemical constituents identified in the aerial parts of Achillea alpina and what is currently known about them from published research.

Sesquiterpene lactones: Sesquiterpene lactones are among the most abundant and structurally diverse constituents in Yi Zhi Hao. Recent studies have isolated a range of germacranolide-type and guaianolide-type sesquiterpenoids from the aerial parts, including several novel compounds named achigermalides A-H. Some of these sesquiterpenoids have been shown in pre-clinical studies to reduce insulin resistance in palmitic acid-treated HepG2 cells via inhibition of the NLRP3 inflammasome pathway. Other guaianolide derivatives with hypoglycemic activity have also been reported. These findings are based on in-vitro and cellular models and do not represent confirmed clinical effects in humans.

Flavonoids and phenolic compounds: Yi Zhi Hao contains flavonoids and phenolic acids, including isochlorogenic acids A and B. A 2020 study identified isochlorogenic acids A and B as transient receptor potential vanilloid 3 (TRPV3) channel antagonists through bioassay-guided fractionation. These compounds have been investigated for their potential anti-inflammatory and analgesic properties in pre-clinical models. The overall flavonoid profile of A. alpina contributes to the antioxidant activity reported for the plant extracts.

Alkamides: A 2022 study reported the isolation of three new alkamides, named achilleamides B-D, along with five known alkamides from the aerial parts of Yi Zhi Hao. These compounds were evaluated for their neuroprotective activity in preliminary in-vitro assays. Alkamides are a class of compounds known for their bioactivity in other Achillea species, and their presence in A. alpina expands the chemotaxonomic and pharmacological understanding of this species.

Essential oils: The essential oil of Yi Zhi Hao (AHO) has been the subject of recent investigation. A 2025 study published in the Journal of Ethnopharmacology analyzed the anti-inflammatory effect of AHO in a zebrafish tail fin amputation model using multi-omics analysis. The essential oil composition typically includes monoterpenes and sesquiterpenes, though the specific chemotype may vary depending on geographical origin and harvest time.

Other constituents: Yi Zhi Hao also contains sterols, triterpenoids, and various other secondary metabolites. A 2025 study identified a range of terpenoids and steroids from the aerial parts that showed PTP1B inhibitory activity in kinetic analysis and molecular docking studies, suggesting potential relevance to diabetes research. Most research on these secondary compounds remains at the pre-clinical stage.

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.

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 effects of essential oil: A 2025 study by Cheng et al. published in the Journal of Ethnopharmacology investigated the anti-inflammatory effect of essential oil extracted from Achillea alpina (AHO) using a zebrafish tail fin amputation model. The study employed multi-omics analysis to characterize the molecular mechanisms underlying the observed anti-inflammatory activity. Results suggested that AHO may modulate inflammatory pathways at the transcriptomic and metabolomic levels. While these findings are scientifically interesting, zebrafish models are not directly translatable to human inflammatory conditions, and human studies are needed to confirm any clinical relevance.

Anti-diabetic potential of sesquiterpenoids: Multiple studies by Xue et al. have investigated the potential anti-diabetic effects of sesquiterpenoids from Yi Zhi Hao. A 2022 study reported that germacranolide- and guaianolide-type sesquiterpenoids could reduce insulin resistance in palmitic acid-treated HepG2 cells via inhibition of the NLRP3 inflammasome pathway. A 2023 study further identified monomeric and dimeric guaianolides with hypoglycemic activity. Another 2023 study in the Chinese Journal of Natural Medicines reported eight novel seco-guaianolide sesquiterpenoids with antidiabetic activity. A 2025 study identified terpenoids and steroids from Yi Zhi Hao as PTP1B inhibitors, a target relevant to type 2 diabetes management. These findings are all based on in-vitro cellular assays; no human clinical trials have been conducted.

Neuroprotective effects of alkamides: A 2022 study by Li et al. published in Chemistry & Biodiversity reported the isolation of three new alkamides (achilleamides B-D) and five known alkamides from Yi Zhi Hao, and evaluated their neuroprotective activity in preliminary in-vitro assays. The study suggested that these alkamides may have potential for protecting neuronal cells from oxidative stress-induced damage. However, these findings are at a very early stage of investigation and do not support any clinical neuroprotective claims.

Antioxidant and antimelanogenic activities: A 2019 study by Lee et al. published in Chemistry & Biodiversity investigated the antioxidant and antimelanogenic activities of compounds isolated from Yi Zhi Hao. Several compounds showed free radical scavenging activity in DPPH and ABTS assays and inhibited melanin production in B16F10 melanoma cells. These findings are limited to in-vitro experiments and do not constitute evidence for clinical whitening or anti-aging effects in humans.

What the research does NOT show: Despite the growing body of pre-clinical research, the studies on Yi Zhi Hao and its active compounds do 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 Yi Zhi Hao can treat, cure, or prevent diabetes, inflammatory disorders, neurodegenerative diseases, or any other medical condition. The translation from in-vitro and animal models to human clinical relevance is uncertain. This page does not endorse Yi Zhi Hao 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: Yi Zhi Hao is a folk herb with limited published safety data. Unlike many officially listed TCM herbs, it has not been systematically evaluated in toxicological studies, and there are no established standards for safe dosage ranges. The information below reflects what is currently known from published literature, traditional empirical experience, and extrapolation from related Achillea species.

Pregnancy and lactation: Yi Zhi Hao is traditionally contraindicated during pregnancy. The genus Achillea is known to contain thujone and other terpenoids that have been associated with uterine stimulant effects in pre-clinical studies. Additionally, the herb's strong Qi-regulating and dispersing nature in TCM theory is considered incompatible with pregnancy. Yi Zhi Hao should not be used during pregnancy or lactation. Women who are planning to become pregnant should also avoid its use.

Yin deficiency with Heat: In traditional TCM theory, Yi Zhi Hao is warm, pungent, and drying in nature. Individuals with Yin deficiency patterns presenting as Heat signs — such as night sweats, a red tongue with little or no coating, flushed cheeks, and a thready rapid pulse — should generally avoid Yi Zhi Hao. Its warm, drying nature may theoretically aggravate Yin deficiency and consume body fluids.

Bleeding disorders and anticoagulant use: Some Achillea species have been reported to contain coumarins and other constituents with potential antiplatelet or anticoagulant effects in pre-clinical studies. While specific data for A. alpina are lacking, individuals with bleeding disorders, those scheduled for surgery, or those taking anticoagulant or antiplatelet medications should exercise caution and consult a healthcare professional before using Yi Zhi Hao.

Allergic reactions: As a member of the Asteraceae family, Yi Zhi Hao may cause allergic reactions in individuals sensitive to other Asteraceae plants, including ragweed, chrysanthemums, marigolds, and daisies. Cross-reactivity between Asteraceae species is well documented in the allergological literature. Individuals with known Asteraceae allergies should avoid Yi Zhi Hao.

Drug interactions: Formal drug interaction studies for Yi Zhi Hao have not been conducted. Based on its known constituents, theoretical interactions may include: modulation of cytochrome P450 enzymes by sesquiterpene lactones (potentially affecting the metabolism of drugs processed through these pathways), additive effects with sedatives or CNS depressants (given the essential oil components), and potential interactions with antidiabetic medications (given the reported hypoglycemic activity in cellular models). However, clinical interaction data are entirely absent. Consult a qualified healthcare professional before combining Yi Zhi Hao with any prescription medications.

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