Anthemis cotula (Asteraceae) Mayweed, Stinking Chamomile, Dog Fennel
Anthemis cotula is a plant of striking contrasts: a delicate, daisy-like appearance concealing a harsh, acrid chemistry and a reputation for causing contact dermatitis. Native to Europe, North Africa, and Western Asia, it has become a widespread weed across temperate regions of the world, thriving in disturbed soils, agricultural fields, and roadsides. The plant is often confused with true chamomile (Matricaria chamomilla), but its unpleasant odour, lack of ray floret reflex, and irritant properties set it apart. Traditional medicine used it cautiously for digestive complaints, menstrual cramps, and as a vermifuge, but its toxicological profile has largely removed it from modern herbal practice. Contemporary research from 2025 and 2026 is now documenting its antimicrobial and insecticidal properties, its allelopathic potential, and the precise chemical basis of its irritant and toxic effects, revealing a plant whose biochemistry demands respect.
Photographs © Upasana Raj, Portland. Used with permission.
1. Taxonomic Insights
Species: Anthemis cotula L.
Family: Asteraceae (Compositae)
Genus: Anthemis
Basionym: Anthemis cotula L. (no change; original Linnaean designation)
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Botanical Description
Anthemis cotula is an annual herb, typically reaching 15 to 60 centimetres in height, with a fibrous root system and a strong, unpleasant odour when crushed. The plant is glabrous to sparsely hairy, with a branching, bushy habit. It completes its life cycle within two to four months, producing large numbers of seeds that persist in the soil seed bank.
Key Identification Features:
The stem is erect, branched, and often tinged with red or purple. It is glabrous below and slightly hairy above, with a distinctive ridged or furrowed texture. The leaves are alternate, finely dissected, 2 to 5 centimetres long, and bipinnate to tripinnate, giving them a feathery, fern-like appearance. The leaf segments are narrow, linear, and pointed. The inflorescence consists of solitary flower heads, 1.5 to 2.5 centimetres in diameter, borne on long, slender peduncles at the ends of branches. Each flower head has 10 to 15 white ray florets surrounding a central disc of yellow tubular florets. Unlike true chamomile, the ray florets do not reflex downward as the flower matures, and the receptacle is distinctly conical and hollow. The fruit is a small, ribbed achene, 1.5 to 2 millimetres long, without a pappus.
Distribution: Native to Europe, North Africa, and Western Asia. It has been introduced and naturalized throughout temperate North America, South America, southern Africa, Australia, and New Zealand. It grows from sea level to 1,500 metres elevation.
Conservation Status: Not assessed by the IUCN. The plant is considered a common agricultural weed in many regions, particularly in cereal crops and pastures.
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Etymology
The generic name Anthemis derives from the Greek "anthemon," meaning flower, referring to the profuse flowering habit of the genus. The specific epithet cotula is derived from the Greek "kotyle," meaning a small cup or hollow, referring to the hollow receptacle of the flower head.
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2. Common Names
Scientific Name: Anthemis cotula | English: Mayweed, Stinking Chamomile, Dog Fennel, Fetid Chamomile, Wild Chamomile | French: Camomille puante, Anthémis fétide, Camomille des chiens | German: Stinkende Hundskamille, Acker-Hundskamille | Spanish: Manzanilla hedionda, Manzanilla de perro, Manzanilla cimarrona | Italian: Camomilla fetida, Camomilla mezzana | Portuguese: Camomila-de-cachorro, Macela-fétida | Hindi: Not widely established; referred to as Mayweed in botanical literature | Arabic: Babunaj al-kalb (بابونج الكلب, "dog chamomile") | Russian: Pupavka sobach'ya (Пупавка собачья) | Turkish: Köpek papatyası | Dutch: Stinkende kamille
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3. Related Herbs from the Asteraceae Family
Anthemis cotula belongs to the Asteraceae family, one of the largest plant families, containing numerous medicinal species as well as several allergenic and toxic members.
Matricaria chamomilla (German Chamomile): The true chamomile, often confused with Anthemis cotula. It is a safe, effective remedy for digestive, nervous, and skin complaints, with a sweet, apple-like aroma.
Chamaemelum nobile (Roman Chamomile): Another true chamomile with similar uses and an excellent safety profile. Distinguished by its perennial habit and aromatic foliage.
Anthemis nobilis (syn. Chamaemelum nobile): The older name for Roman chamomile, reflecting the historical taxonomic confusion within the genus.
Achillea millefolium (Yarrow): A fellow Asteraceae member with anti-inflammatory, haemostatic, and diaphoretic properties. Shares the family's characteristic volatile oil chemistry.
Tanacetum parthenium (Feverfew): Another asteraceous herb with documented antimigraine activity, but also with potential for contact dermatitis, illustrating the family's chemical diversity and allergenic potential.
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4. Medicinal Uses: Summary of Primary and Secondary Actions
Primary Actions (Historical and Preclinical):
Antispasmodic: Traditionally used to relieve menstrual cramps and gastrointestinal spasms. The volatile oil fraction has demonstrated smooth muscle relaxant activity in isolated tissue preparations.
Vermifuge: Seeds and flowering tops were used to expel intestinal worms, particularly roundworms and threadworms, in European folk medicine.
Diaphoretic: Used to promote sweating and reduce fever in traditional practice, particularly for colds and influenza.
Emmenagogue: Employed historically to stimulate menstrual flow and regulate irregular menstruation.
Rubefacient: The fresh plant applied externally produces local irritation and redness, used for rheumatic pain and neuralgia.
Secondary Actions (Preclinical and Emerging):
Antimicrobial: Essential oil and extracts show activity against a range of bacteria and fungi, including Gram-positive and Gram-negative species.
Insecticidal: The plant produces compounds with documented insecticidal and repellent activity against agricultural pests and stored-product insects.
Allelopathic: Extracts inhibit the germination and growth of competing plant species, contributing to its success as an agricultural weed.
Cytotoxic: Sesquiterpene lactones and other constituents have demonstrated cytotoxic activity in cell culture studies.
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Medicinal Parts
The flowering tops and seeds were the primary medicinal parts in traditional practice, though modern understanding of the plant's irritant and allergenic properties has rendered internal use inadvisable.
Flowering Tops: The primary medicinal part. Used fresh or dried in infusions, decoctions, and tinctures. The volatile oil content is highest at flowering.
Seeds: Used as a vermifuge, typically ground and mixed with honey or other vehicles. Contain the highest concentration of sesquiterpene lactones.
Leaves: Occasionally used fresh as a poultice for external application, though the irritant potential limits this use.
Roots: Not traditionally used.
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5. Phytochemistry
5.1 Sesquiterpene Lactones
The most significant chemical class in Anthemis cotula, responsible for its irritant, allergenic, and cytotoxic properties.
Anthecotulide: The principal sesquiterpene lactone, found in high concentrations in the flowering tops and seeds. It is a potent contact allergen and the primary cause of the plant's irritant reputation.
Farnesol: A sesquiterpene alcohol with antimicrobial and potential anticancer activity.
Artemisia ketone: A volatile sesquiterpene contributing to the plant's characteristic odour.
5.2 Flavonoids
Apigenin: A flavonoid with anti-inflammatory, antioxidant, and anxiolytic properties.
Luteolin: A flavonoid with documented anti-inflammatory, antioxidant, and anticancer activity.
Quercetin: Present in moderate concentrations, contributing to antioxidant activity.
5.3 Essential Oil
The essential oil content ranges from 0.1% to 0.5% in the flowering tops, with significant variation between populations.
α-Pinene: A monoterpene with antimicrobial and anti-inflammatory properties.
β-Pinene: Another monoterpene with antimicrobial activity.
Limonene: A monoterpene with documented chemopreventive and anxiolytic properties.
Myrcene: A monoterpene with sedative and muscle relaxant activity.
β-Caryophyllene: A sesquiterpene with anti-inflammatory and analgesic properties, acting as a selective CB2 receptor agonist.
5.4 Other Compounds
Tannins: Present in moderate amounts, contributing to the astringent properties.
Coumarins: Scopoletin and related compounds have been isolated, with anticoagulant and anti-inflammatory activity.
Polyacetylenes: A class of compounds with antimicrobial and cytotoxic properties, present in the roots and lower stems.
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6. Mechanisms of Action
6.1 Contact Dermatitis: Hapten Formation and Immune Activation
The irritant and allergenic properties of Anthemis cotula are primarily attributed to anthecotulide and related sesquiterpene lactones. These compounds are lipophilic and readily penetrate the stratum corneum. Once in the epidermis, they act as haptens, binding covalently to skin proteins through Michael addition to their α-methylene-γ-lactone group. The modified proteins are recognized as foreign by antigen-presenting cells, triggering a T-cell-mediated hypersensitivity reaction. Repeated exposure leads to sensitization and the development of allergic contact dermatitis, characterized by erythema, vesiculation, and pruritus. The irritant effect is due to direct cytotoxicity and the release of pro-inflammatory mediators from keratinocytes.
6.2 Antispasmodic Activity: Calcium Channel Modulation
The volatile oil fraction, particularly myrcene and β-caryophyllene, has demonstrated smooth muscle relaxant activity in isolated intestinal and uterine tissue preparations. The mechanism involves inhibition of calcium influx through voltage-gated calcium channels, reducing muscle contractility. This provides a pharmacological basis for the traditional use of the plant for menstrual cramps and gastrointestinal spasms.
6.3 Antimicrobial Activity: Membrane Disruption and Enzyme Inhibition
The essential oil components, particularly α-pinene, β-pinene, and limonene, disrupt bacterial and fungal cell membranes, increasing permeability and causing leakage of intracellular contents. Sesquiterpene lactones inhibit microbial enzymes through alkylation of sulphhydryl groups. In vitro studies show activity against both Gram-positive and Gram-negative bacteria, as well as Candida species.
6.4 Insecticidal Activity: Neurotoxicity and Antifeedant Effects
The plant produces compounds with documented insecticidal activity against agricultural pests and stored-product insects. The mechanism involves inhibition of acetylcholinesterase, leading to accumulation of acetylcholine at synaptic junctions and subsequent paralysis. Sesquiterpene lactones also act as antifeedants, deterring insects from consuming plant material.
6.5 Allelopathic Activity: Germination Inhibition
Extracts of Anthemis cotula inhibit the germination and seedling growth of competing plant species. The allelopathic compounds, primarily sesquiterpene lactones and polyacetylenes, interfere with cell division and elongation in target plants. This contributes to the plant's competitive success in agricultural ecosystems.
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7. Traditional and Ethnobotanical Uses
7.1 Menstrual Cramps and Irregularities
Formulation: Infusion of flowering tops.
Preparation and Use: One to two teaspoons of dried flowering tops steeped in a cup of boiling water for ten minutes, consumed once or twice daily. Traditional texts describe this as a "uterine tonic" for painful or irregular menstruation.
Scientific Validation: Antispasmodic activity is supported by in vitro data, but the plant's allergenic and irritant potential renders internal use inadvisable by modern standards. True chamomile is a safer alternative.
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7.2 Intestinal Worms
Formulation: Seed powder.
Preparation and Use: The seeds were ground and mixed with honey or syrup, taken on an empty stomach for three consecutive mornings. This was a common treatment for roundworms and threadworms in European folk medicine.
Scientific Validation: No modern studies support this use. The sesquiterpene lactones are cytotoxic in vitro, but their efficacy as anthelmintics in vivo has not been demonstrated. The risk of toxicity outweighs any potential benefit.
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7.3 Fevers and Colds
Formulation: Infusion of flowering tops.
Preparation and Use: A hot infusion was consumed to promote sweating and reduce fever. Used in combination with other diaphoretic herbs like elderflower and peppermint.
Scientific Validation: Diaphoretic activity is not well documented in pharmacological literature. The traditional use is plausible based on the volatile oil content, but safer alternatives exist.
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7.4 Rheumatic Pain and Neuralgia
Formulation: Fresh plant poultice.
Preparation and Use: The fresh, crushed plant was applied to painful joints and areas of neuralgia, producing local redness and a counterirritant effect. The sensation of warmth was believed to relieve deeper pain.
Scientific Validation: Rubefacient action is consistent with the irritant properties of anthecotulide and other sesquiterpene lactones. However, the risk of severe contact dermatitis makes this use inadvisable.
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7.5 Regional Ethnomedicinal Applications Summary
Europe: Used historically for menstrual complaints, intestinal worms, fevers, and as an external rubefacient. Its use declined sharply in the twentieth century due to recognition of its allergenic properties.
North America: Introduced by European settlers and used similarly for menstrual disorders and as a vermifuge. Some Native American groups adopted it for external applications, with caution.
North Africa and Middle East: Used sparingly for digestive complaints and fevers. The plant's strong odour and irritant properties limited its popularity.
Asia: Limited use. In some regions, related Anthemis species were used more commonly, often with similar cautions.
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8. Healing Recipes, Teas, Decoctions, and Practical Applications
8.1 Cautionary Note on Internal Preparations
No internal preparation of Anthemis cotula can be recommended. The sesquiterpene lactones, particularly anthecotulide, are potent contact allergens and potential systemic toxicants. Historical recipes exist in old herbals, but they belong to a pre-scientific understanding of the plant's chemistry and should not be followed.
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8.2 Identification and Avoidance
Purpose: To prevent accidental confusion with true chamomile and subsequent allergic reactions.
Preparation and Use: Learn to distinguish Anthemis cotula from Matricaria chamomilla by three key features. The odour of A. cotula is unpleasant and acrid when crushed, while true chamomile has a sweet, apple-like aroma. The receptacle of A. cotula is solid and conical, while that of M. chamomilla is hollow. The ray florets of A. cotula do not reflex downward as the flower matures, while those of M. chamomilla do.
Scientific Validation: Accurate identification is essential for safe use of chamomile and avoidance of Anthemis cotula. Misidentification is a common cause of allergic reactions to "chamomile" products.
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8.3 External Caution
The fresh plant should not be applied to the skin, even as a poultice for rheumatic pain. The risk of severe contact dermatitis, particularly in sensitized individuals, makes this use actively dangerous. Those with known allergies to Asteraceae plants (ragweed, chrysanthemum, daisy) are at elevated risk.
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8.4 Culinary Uses and Nutritional Information
Anthemis cotula has no culinary use. Its unpleasant odour and irritant properties preclude consumption as a food. It should not be confused with edible chamomile or other Asteraceae greens.
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9. Clinical Significance and Evidence Summary
9.1 Evidence Hierarchy by Activity
Contact Dermatitis: Definitive evidence from human case reports, patch testing studies, and animal models. Anthecotulide is a well-characterized contact allergen. This is the most clinically significant property of the plant.
Antimicrobial: Moderate evidence from in vitro studies. Essential oil and extracts show activity against a range of pathogens, but no human trials exist.
Antispasmodic: Limited evidence from isolated tissue studies. The traditional use is plausible but not clinically validated.
Insecticidal: Moderate evidence from agricultural research. The plant's insecticidal compounds are well characterized, but development of commercial products has not occurred.
Allelopathic: Well-documented in agricultural research. Not a medicinal application.
Cytotoxic: Preliminary evidence from in vitro studies. Sesquiterpene lactones show activity against cancer cell lines, but no animal or human data exist.
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9.2 Clinical Trial Data
No human clinical trials have been conducted for any therapeutic indication. The plant's toxicological profile has excluded it from modern clinical research.
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9.3 Safety and Toxicology Data
Human case reports of contact dermatitis from Anthemis cotula are well documented in dermatological literature. Patch testing confirms anthecotulide as the primary allergen. Sensitization can occur after a single exposure, and subsequent exposures produce increasingly severe reactions. Systemic toxicity from internal use is poorly documented, as the plant fell out of use before systematic toxicological study, but the sesquiterpene lactone content raises concerns about hepatotoxicity, nephrotoxicity, and gastrointestinal irritation.
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10. Safety and Toxicology
10.1 Toxicity Profile
Acute Toxicity: Large doses of the plant may cause gastrointestinal irritation, vomiting, and diarrhoea. The sesquiterpene lactones are cytotoxic and potentially hepatotoxic.
Chronic Toxicity: Chronic exposure, particularly through repeated skin contact, leads to sensitization and increasingly severe allergic reactions. Systemic effects of chronic internal use are not well characterized due to the plant's abandonment from herbal practice.
Allergenicity: Anthecotulide is a potent contact allergen. Sensitization is common among agricultural workers who handle the plant regularly. Cross-reactivity with other Asteraceae allergens is well documented.
10.2 Contraindications and Precautions
Internal Use: Absolutely contraindicated. No infusion, decoction, tincture, or supplement prepared from Anthemis cotula should be consumed.
Topical Use: Contraindicated due to the risk of severe contact dermatitis.
Pregnancy and Lactation: Contraindicated in all forms.
Children: Contraindicated. Children are more susceptible to allergic sensitization.
Asteraceae Allergy: Individuals with known allergies to ragweed, chrysanthemum, daisy, or other Asteraceae plants must avoid this plant entirely.
10.3 Potential Drug Interactions
No drug interactions are documented, as the plant is not used in modern medicine. The sesquiterpene lactones may theoretically interact with hepatic enzymes, but the risk is irrelevant given the contraindication against internal use.
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11. Quality Control Parameters
11.1 Marker Compounds for Standardisation
For safety assessment and research purposes, anthecotulide is the primary marker compound. Total sesquiterpene lactone content and essential oil composition serve as additional quality parameters.
11.2 Recommended Analytical Methods
High-performance liquid chromatography (HPLC) with UV or mass spectrometry detection is used for quantification of anthecotulide and related sesquiterpene lactones. Gas chromatography with mass spectrometry (GC-MS) is recommended for essential oil analysis.
11.3 Suggested Specifications
There are no therapeutic specifications, as the plant is not used in modern medicine. For research purposes, any material should be clearly labelled with anthecotulide content and handled as a potential allergen and toxicant.
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12. Cultivation and Sustainability
12.1 Growth Requirements
Climate: Temperate. Tolerates a wide range of conditions but prefers cool, moist springs.
Habitat: Disturbed soils, agricultural fields, roadsides, and waste ground.
Altitude: Grows from sea level to 1,500 metres.
Soil: Adaptable to most soil types, preferring heavy, clay-rich soils with adequate moisture.
Propagation: Exclusively by seed. Seeds germinate readily in spring and autumn, with no specific pre-treatment requirements.
12.2 Sustainable Harvesting
The plant is not cultivated commercially. It is regarded as a weed and is more commonly controlled than harvested. Any research collection should be conducted with awareness of its allergenic potential and should not deplete natural populations, though this is rarely a concern given its abundance.
12.3 Conservation Status
Not threatened. Anthemis cotula is a widespread and successful weed throughout temperate regions of the world. It is considered invasive in parts of North America, Australia, and New Zealand.
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13. Cultivar and Varietal Comparison
Anthemis cotula shows limited morphological variation across its range, and no formal cultivars exist.
Typical Form: The common, widespread form with white ray florets and yellow disc florets.
Disc Form: A rare variant lacking ray florets, with only yellow disc florets present. Occasionally found in disturbed habitats.
Related Species: Anthemis arvensis (Corn Chamomile) is a closely related species with similar morphology but a less unpleasant odour and lower allergenic potential. Anthemis tinctoria (Yellow Chamomile) is another relative with yellow ray florets, used historically as a dye plant.
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14. Research Gaps and Future Directions
14.1 Critical Research Gaps
Allergenicity Mechanisms: While anthecotulide is recognized as the primary allergen, the precise immunological mechanisms of sensitization and the factors influencing individual susceptibility remain incompletely characterized.
Systemic Toxicity: The systemic toxicity of the sesquiterpene lactones is poorly understood due to the plant's abandonment from herbal practice. Animal studies are needed to characterize the hepatotoxic, nephrotoxic, and reproductive effects.
Cross-Reactivity: The extent of cross-reactivity between anthecotulide and other Asteraceae allergens, particularly those in true chamomile, requires further investigation to inform allergy management.
Chemical Variation: The variation in anthecotulide and volatile oil content across different populations and environmental conditions is poorly documented.
14.2 Future Research Priorities
Allergen Standardization: Development of standardized anthecotulide preparations for patch testing and allergy research.
Structure-Activity Studies: Investigation of the relationship between sesquiterpene lactone structure and allergenic potency, potentially leading to the identification of less allergenic analogues.
Insecticidal Development: Characterization of the insecticidal compounds for potential development as natural pesticides, building on the documented activity against agricultural pests.
Allelochemical Characterization: Further identification and characterization of the allelopathic compounds, potentially leading to novel herbicide development.
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15. Commercial Applications
15.1 None in Modern Medicine
Anthemis cotula has no legitimate commercial application in modern medicine. Its allergenic and irritant properties preclude any use in pharmaceuticals, nutraceuticals, or herbal products.
15.2 Research Tool
Anthecotulide serves as a model compound for studying contact dermatitis mechanisms and developing in vitro assays for allergenicity testing.
15.3 Potential Insecticidal Development
The insecticidal compounds have been investigated for potential development as natural pesticides, though no commercial products have emerged.
15.4 Allelopathic Development
The allelopathic compounds have been investigated for potential development as natural herbicides, though no commercial products have emerged.
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16. Related Plants for Further Study
Matricaria chamomilla (German Chamomile): The true chamomile, often confused with Anthemis cotula. A safe, effective remedy for digestive, nervous, and skin complaints.
Chamaemelum nobile (Roman Chamomile): Another true chamomile with similar uses and an excellent safety profile.
Anthemis arvensis (Corn Chamomile): A closely related species with similar morphology but lower allergenic potential.
Achillea millefolium (Yarrow): A fellow Asteraceae member with anti-inflammatory and haemostatic properties.
Tanacetum parthenium (Feverfew): Another asteraceous herb with documented antimigraine activity, illustrating the family's chemical diversity.
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17. Reference Literature
Primary Research
Contact dermatitis case series (2015) documents clinical outcomes in patients sensitized to anthecotulide through occupational exposure, confirming the allergen's potency.
Antimicrobial activity study (2020) demonstrates the in vitro activity of essential oil and extracts against Gram-positive and Gram-negative bacteria and Candida species.
Sesquiterpene lactone profiling study (2018) characterizes anthecotulide and related compounds across different populations and growth stages.
Insecticidal activity study (2019) documents the activity of extracts against agricultural pests and stored-product insects.
Allelopathic activity study (2017) characterizes the germination-inhibiting effects of extracts on crop and weed species.
Allergenicity review (2016) comprehensively documents the contact dermatitis potential of Anthemis species and the role of sesquiterpene lactones.
Key Monographs and Floras
Flora Europaea: Provides comprehensive botanical descriptions and distribution data for the species across Europe.
Flora of North America: Documents the species' naturalization and distribution in North America.
British Herbal Pharmacopoeia (1983): Includes the species with cautions regarding its allergenic potential.
Handbook of Medicinal Herbs: Documents traditional uses and toxicological data.
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18. Disclaimer
Anthemis cotula contains potent contact allergens, particularly anthecotulide, which can cause severe allergic reactions. Internal use is absolutely contraindicated. Topical use is contraindicated.
This information is for educational and academic purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
Pregnant or nursing women and children must not use this plant in any form.
Individuals with known allergies to Asteraceae plants (ragweed, chrysanthemum, daisy, chamomile) must avoid this plant entirely.
Do not confuse Anthemis cotula with true chamomile (Matricaria chamomilla). Accurate identification is essential to prevent allergic reactions.
Always consult a qualified healthcare practitioner before using any plant for medicinal purposes.
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