Yarrow

Metadata

Approved Indications

Commission E (Germany)

• Approved:
  • Loss of appetite (appetitlosigkeit)
  • Dyspeptic complaints
  • Liver and gallbladder complaints (hepatobiliary disorders)
• Commission E lists yarrow as a bitter aromatic, recognizing its choleretic and spasmolytic properties
• Also approved for sitz baths in painful, crampy conditions of the lower pelvis in women (balneotherapy indication)

ESCOP Monograph

• No monograph issued
• ESCOP has not published a monograph on Achillea millefolium

EMA/HMPC

• Traditional use: Temporary loss of appetite
• Traditional use: Symptomatic relief of mild, spasmodic gastrointestinal complaints including bloating and flatulence
• Traditional use: Treatment of small superficial wounds (topical)
• EMA classification: Traditional herbal medicinal product (Article 16a)
• The HMPC explicitly noted that clinical data are insufficient for well-established use status

Agreement/Disagreement Between Bodies

• Partial agreement between Commission E and EMA on appetite stimulation and dyspeptic complaints
• Commission E includes liver and gallbladder complaints, which EMA does not specifically list
• Commission E uniquely includes the balneotherapy (sitz bath) indication for pelvic complaints in women
• EMA adds topical wound treatment, which Commission E does not address in its yarrow monograph
• ESCOP gap: The absence of an ESCOP monograph is notable and reflects the lack of clinical trial data
• All regulatory opinions rest on traditional use rather than clinical evidence

Conditions Treated

Primary (Strong Evidence)

• No conditions have strong clinical trial evidence
• The following are supported by regulatory approval based on traditional use:
  • Loss of appetite / appetite stimulation (Commission E, EMA)
  • Dyspeptic complaints — bloating, flatulence, feelings of fullness (Commission E, EMA)
  • Mild GI spasms (EMA)

Secondary (Moderate Evidence)

• Liver and gallbladder complaints — choleretic action (Commission E; pharmacological support)
• Minor wound healing — topical application (EMA traditional use; anti-inflammatory and antimicrobial constituents)
• Painful pelvic conditions in women — sitz bath (Commission E; traditional use only)

Traditional/Historical (Limited Evidence)

• Hemorrhoidal complaints (folk medicine)
• Menstrual cramps / dysmenorrhea (traditional European and folk use)
• Inflammatory skin conditions (topical)
• Common cold symptoms (diaphoretic use — promoting sweating)
• Mild bleeding (styptic/hemostatic — the genus name Achillea references the legend of Achilles using yarrow to treat soldiers’ wounds)
• Hypertension (folk medicine, no clinical evidence)
• Urinary tract complaints (folk medicine)

Mechanism of Action

Primary Mechanisms

Bitter-tonic appetite stimulation

• Achillein (a betonicine-type alkaloid) and sesquiterpene lactones contribute bitter taste
• Bitter compounds activate TAS2R (bitter taste receptors) on the tongue and in the GI tract
• Triggers reflex stimulation of salivary, gastric acid, and bile secretions
• Same pharmacological principle as gentian and wormwood, though yarrow is a weaker bitter (bitterness value approximately 3,000-4,000, compared to gentian’s 10,000-25,000)

Spasmolytic (antispasmodic) activity

• Flavonoids (apigenin, luteolin, artemetin) have demonstrated smooth muscle relaxant activity in isolated tissue preparations
• Apigenin acts as a partial agonist at GABA-A receptors and inhibits calcium influx in smooth muscle cells
• The essential oil component (particularly 1,8-cineole and borneol) contributes to spasmolytic effects
• This dual bitter-spasmolytic profile (appetite stimulation plus cramp relief) is characteristic of “bitter aromatic” herbs in European phytotherapy

Secondary Mechanisms

Anti-inflammatory activity

• Proazulenes (matricine) are converted to chamazulene during steam distillation; chamazulene inhibits leukotriene synthesis and has demonstrated anti-inflammatory effects comparable to (but weaker than) those in German chamomile
• Sesquiterpene lactones inhibit NF-kB-mediated inflammatory pathways
• Salicylic acid derivatives contribute mild anti-inflammatory activity (present in small amounts)

Choleretic (bile-stimulating) effects

• Essential oil components and flavonoids stimulate bile production and secretion
• This underlies the Commission E indication for liver and gallbladder complaints
• Mechanism is less well-characterized than the appetite-stimulating effect

Hemostatic and wound-healing effects

• Achillein has been reported to have mild hemostatic (blood-clotting) properties in older pharmacological literature
• Tannin content provides astringent action on wound surfaces
• Essential oil has modest antimicrobial activity against common wound pathogens

Clinical Evidence Summary

Volume and Quality of Evidence

• Virtually no modern clinical trial data: No randomized controlled trials were identified for any indication
• The evidence base consists almost entirely of:
  • Traditional use documentation spanning centuries of European herbal practice
  • Pharmacological (in vitro and animal) studies supporting the mechanisms described above
  • Expert consensus within European phytotherapy organizations
  • European Pharmacopoeia quality monograph (compositional standards)

Pharmacological Studies (Preclinical)

• Spasmolytic activity: Confirmed in isolated guinea pig ileum and rabbit jejunum preparations (aqueous and ethanolic extracts)
• Choleretic activity: Demonstrated in rat bile flow studies (aqueous extract)
• Anti-inflammatory: Chamazulene from yarrow oil inhibited leukotriene B4 synthesis in human neutrophils
• Antimicrobial: Essential oil showed activity against Staphylococcus aureus, E. coli, and Candida albicans in vitro (clinical relevance uncertain)

Evidence Assessment

• Overall: This is a traditional use herb with pharmacological plausibility but essentially no clinical trial evidence. The regulatory approvals (Commission E, EMA) are explicitly based on historical use documentation rather than clinical studies
• The EMA assessment report states: “Clinical efficacy has not been established through clinical studies; the plausibility of the pharmacological action supports the traditional use”
• Yarrow is typical of many Commission E-approved herbs where the monograph was based on 1980s-era pharmacognostic knowledge and traditional use, and no subsequent clinical investigation has occurred

European vs US/Anglophone Consensus

Safety Profile

Contraindications

• Known hypersensitivity to Achillea millefolium or other Asteraceae (Compositae) family plants — cross-reactivity is well-documented with ragweed, chrysanthemum, daisy, and marigold allergens
• Active gastric or duodenal ulcer (due to bitter-mediated gastric acid stimulation)
• Obstruction of the bile duct (due to choleretic activity)

Drug Interactions

• No clinically significant drug interactions documented
• Theoretical: the small amount of salicylic acid derivatives could theoretically interact with anticoagulants, but concentrations in typical doses are too low to be clinically relevant
• Theoretical: choleretic effect could alter absorption of concurrently administered drugs, but no documented cases
• The EMA assessment report does not list any specific drug interactions

Side Effects

• Generally well tolerated at recommended doses
• Occasional: allergic contact dermatitis (especially in individuals sensitive to Asteraceae plants)
• Rare: photodermatitis (sensitization to UV light after topical application)
• Rare: GI discomfort at higher doses
• Allergenic potential: Yarrow contains sesquiterpene lactones (alpha-peroxyachifolid) that are known contact allergens; cross-sensitivity with other Asteraceae plants is common

Pregnancy/Lactation

• Not recommended during pregnancy — thujone content in essential oil is a potential concern (uterotonic/abortifacient at high doses); traditional emmenagogue reputation
• Insufficient data on lactation safety; avoid therapeutic doses
• EMA: “Not recommended for children and adolescents under 12 years of age due to lack of adequate data”

Clinical Dosage

Key point: Yarrow is traditionally taken as a tea infusion 30 minutes before meals for appetite stimulation, leveraging the bitter taste reflex. The tea should be drunk unsweetened to preserve the bitter-mediated mechanism of action.

Sources

• German Commission E Monograph: Millefolii herba (Yarrow herb)
• EMA/HMPC Assessment Report on Achillea millefolium L., herba
• EMA/HMPC Herbal Monograph on Achillea millefolium L., herba
• European Pharmacopoeia Monograph: Millefolii herba (Yarrow)
• Wichtl M (ed). Herbal Drugs and Phytopharmaceuticals. 3rd ed. Medpharm/CRC Press. 2004. Millefolii herba pp. 369-373
• Nemeth E, Bernath J. Biological activities of yarrow species (Achillea spp.). Curr Pharm Des. 2008;14(29):3151-3167
• Benedek B, et al. Achillea millefolium L. s.l. — is the anti-inflammatory activity mediated by protease inhibition? J Ethnopharmacol. 2007;113(2):312-317
• Applequist WL, Moerman DE. Yarrow (Achillea millefolium L.): A neglected panacea? J Ethnopharmacol. 2011;136(1):1-14

Connections

• Compare with German Chamomile for overlapping spasmolytic and anti-inflammatory GI indications — both contain proazulenes (chamazulene precursors), but chamomile has a much stronger clinical evidence base
• Compare with Gentian and Wormwood as fellow bitter digestive tonics for appetite stimulation — gentian is a far more potent bitter, while yarrow combines bitter with spasmolytic properties
• Compare with Calendula for overlapping wound-healing indications as fellow Asteraceae herbs
• Yarrow is a classic example of a “bitter aromatic” in European phytotherapy, combining the appetite-stimulating properties of bitters with the spasmolytic properties of aromatic essential oils