Tansy

Tansy (Tanacetum vulgare L.): A Comprehensive Reference

1. Identity and Botanical Profile

Nomenclature and Taxonomy

Tansy (Tanacetum vulgare) is a perennial, herbaceous flowering plant in the genus Tanacetum in the aster family (Asteraceae), native to temperate Europe and Asia. It is synonymous with and formerly known as Chrysanthemum vulgare. It is also known as common tansy, bitter buttons, cow bitter, or golden buttons. The genus name is reportedly derived from an altered form of the Greek word athanatos, meaning "long-lasting" or "immortal," in reference to the long-lasting flowers and everlasting qualities of the dried flowers. The Latin species epithet vulgare means "common."

Morphological Description

T. vulgare is a 50–100 cm tall perennial herbaceous plant. The stem is straight, branched from the middle, furrowed, glabrous, or slightly pubescent. The leaves are alternate, dark green on top, grayish on the bottom, and pubescent. The lower leaves are short-petiolate, the rest are sessile. All the leaves are pinnately lobed, divided into lanceolate lobes with saw-toothed edges. The anthodia are numerous, 5–8 mm in diameter, and arranged in corymbose inflorescences at the top of the stem. All the flowers are yellow and funnel shaped. The fruits are oblong gray achenes 1.5–3 mm long with five ribs. The plant blooms from mid-June to September and the fruits ripen in August–September.

Geographic Distribution

Tansy is native to Britain, Channel Islands, and across Europe, and has been introduced in Ireland and across North, Central and South America. It was grown in medieval gardens as a medicinal or culinary herb, and due to spreading from cultivation it is now widely distributed and naturalised. Tansy grows well in full sun, nutrient-rich, moist but well-drained soil and can be found growing wild in grassy places, verges, riverbanks, roads, railways, and on waste ground. It has been introduced to other parts of the world, including North America, and in some areas has become invasive.

Plant Parts Used and Common Preparations

In ethnomedicinal practice, the leaves (45.31%), flowers (18.76%), and aerial parts (15.63%) are the predominant plant parts used. Common preparations encountered in both traditional and scientific literature include:

• Aqueous extract / decoction / infusion: Made from dried or fresh leaves and flowers steeped or boiled in water.
• Alcoholic / hydroethanolic extract: Produced by macerating plant material in ethanol or ethanol–water mixtures, widely used in laboratory research.
• Essential oil: Obtained by hydrodistillation, rich in bicyclic monoterpenes, and characterized by gas chromatography–mass spectrometry.
• Standardized pharmaceutical preparation: Tanacechol®, a purified complex extract of flavonoids and phenolcarbonic acids extracted from tansy flowers (0.05 g/tablet), is registered in Russia as a choleretic and spasmolytic agent for chronic cholecystitis and biliary dyskinesia.
• Topical applications: Poultices made from plant material applied externally.

2. Traditional and Historical Use

Ancient and Classical Use

Dating back to ancient Greece and Rome, this plant has a long history of use as a folk medicine remedy for a number of problems including plague, colic, parasitic worms, fever, gout, digestive disorders, and hysteria.

Medieval Europe and Monastic Gardens

Tansy was grown in the garden of Charlemagne the Great in the eighth century and in the herb gardens of Swiss Benedictine monks as a treatment for intestinal worms, rheumatism, fevers, and digestive problems. It was grown in medieval gardens as a medicinal or culinary herb. The herbalist John Gerard (c. 1545–1612) noted tansy's culinary and medicinal properties, and he recommended tansy sweetmeats as "an especial thing against the gout, if every day for a certain space a reasonable quantitie thereof be eaten fasting."

Culinary Use

Tansy was formerly used as a flavouring for puddings and omelettes, but is now almost unknown, except in Cork, where it is used in a sauce to accompany drisheens. In Yorkshire, tansy and caraway seeds were traditionally used in biscuits served at funerals.

Preservative and Funerary Use

Common tansy was also frequently used in early American history for funeral shrouds and wreaths. In 1668, the first president of Harvard University was buried wearing a common tansy wreath in a common tansy–lined coffin. Due to its preservative properties, common tansy was commonly used in colonial America for packing meat and other perishable goods. This use has been substantiated by contemporary research which has isolated compounds with fungicidal and antibacterial properties.

Colonial North America

Because of its popular uses, the governor of Massachusetts listed common tansy as a necessary plant for colonial herb gardens in the 1600s. This led to widespread cultivation of common tansy and the inevitable escape of the plants into fields and roadsides.

Native American Adoption

Native Americans also began incorporating tansy into their medicinal practices when Europeans introduced it to North America, probably being already familiar with the plant's native relatives like Camphor Tansy (Tanacetum camphoratum). The Cherokee made tansy infusions for treating backaches and as an herbal tonic. They also wore wreaths of the plant around their waists to prevent miscarriages. The Cheyenne also used a tansy infusion, made from crushed leaves and flowers, to treat dizziness and weakness.

Traditional European Folk Medicine

Common tansy has traditionally been used in folk medicine for its anthelmintic, antispasmodic, and choleretic effects, for the treatment of diarrhea and digestive problems, and externally as an insecticide in veterinary practices. The plant is also mentioned regarding its use in treating hysteria, migraine, neuralgia, rheumatism, kidney weakness, stomach problems, and fever. Traditionally, Tanacetum vulgare has been attributed with anthelmintic, carminative, antispasmodic, stimulant (to the abdominal viscera), tonic, emmenagogue, antidiabetic, diuretic, and antihypertensive properties. Externally, tansy is used as a poultice on swellings, sprains, gout, contusions, and some eruptive skin diseases, and to kill lice and fleas and treat scabies.

Emmenagogue and Abortifacient Use

Traditionally, tansy was often used for its emmenagogue effects to bring on menstruation or end an unwanted pregnancy, and pregnant women are advised not to use this herb. In larger doses, the plant has been used to induce abortion.

Irish and Other Folk Traditions

According to Irish folklore from the 19th century, a bath of tansy and salts would cure joint pain. Tansy was hung on the house by Germanic peoples as protection against monsters. The aromatic herb was also burned as incense.

3. Phytochemistry: Key Constituents and Active Compounds

Essential Oil Composition

Tanacetum vulgare L. (Asteraceae) is a perennial herb. Regional variability of the chemical composition of T. vulgare essential oils is well-known. The essential oil is rich in bicyclic and oxygenated monoterpenes, and its precise composition depends heavily on geographic origin, season of harvest, and plant part extracted. The chemical composition of the essential oil is dominated by monoterpene hydrocarbons (approximately 6.12%), oxygenated monoterpenes (approximately 79.55%), and oxygenated sesquiterpenes (approximately 1.17%) in Bulgarian material.

Among the major constituents identified in Bulgarian tansy EO were oxygenated monoterpenes including camphor (25.24%), trans-chrysantenyl acetate (18.35%), cis-verbenol (10.58%), thujone (6.06%), eucalyptol (5.99%), and α-campholenal (5.98%). By contrast, in material from northern Quebec, the major compounds were identified as camphor, borneol, and 1,8-cineole. Some chemotypes, particularly from central Europe, historically showed high thujone content — volatile oil containing up to 70% thujone has been reported in certain specimens.

Thujone: The Primary Toxic Constituent

Thujone exists in two isomeric forms, α- and β-thujone. Regarding the degree of toxicity of the two forms, α-thujone has a higher toxicity than β-thujone. Thujone with neurotoxicity: α-thujone has stronger neurotoxicity than β-thujone, and both can cause acute and chronic toxicity, which is manifested by seizures of varying degrees. Thujone (α + β) has previously been reported only for the essential oil of T. vulgare, not for aqueous leaf extracts.

Sesquiterpene Lactones

T. vulgare comprises sesquiterpenes and sesquiterpene lactones, flavonoid derivatives, hydroxycoumarins, sterols, tannic acid, resins, and essential oil components. A key sesquiterpene lactone present in the plant is parthenolide. Parthenolide has been identified among the principles responsible for the anti-inflammatory activity of T. vulgare, showing 93% oedema inhibition at 0.5 mg/ear (ID50 = 0.18 μmol/ear) in mouse-ear oedema models. However, lower parthenolide content of T. vulgare compared to some other Tanacetum species proved that parthenolide was not the only constituent responsible for anti-inflammatory activity.

Flavonoids and Phenolic Acids

The main flavonoid aglycone in tansy has been identified as luteolin, and the presence of flavonoids, phenolic acids, and terpenoids in T. vulgare L. extracts has been confirmed analytically. Biologically active substances such as luteolin-7-glucoside (550.80 mg/kg), chlorogenic acid (5945.40 mg/kg), and rosmarinic acid (661.31 mg/kg) have been identified by HPLC. Methanol extracts are characterized by the presence of neochlorogenic, 3,5-O-dicaffeoylquinic, and caffeoylquinic acids. High phenolic content in methanol extracts correlates with high antioxidant capacity, especially for roots.

The flavonoids found in tansy also include the methoxyflavones jaceosidin, eupatorin, chrysoeriol, and diosmetin, which have been implicated in anti-inflammatory activity. These methoxyflavones were identified alongside parthenolide as anti-inflammatory constituents, though in molar terms the potency of parthenolide was nearly three times greater than that of the most active of the flavones, meaning flavonoids are only partially responsible for anti-inflammatory effects.

Other Identified Compounds

A large number of constituents have been identified in tansy, including thujone, camphor, alpha-pinene, borneol, tanacetin, sesquiterpenes, flavonoids, hydroxycoumarins, polyynes, sterols, tannic acid, and resins. Over the past three decades, 241 metabolites have been isolated from nearly twenty Tanacetum species, including phenolic acids, flavonoids, coumarins, fatty acids and alkanes, aldehydes, volatile compounds, and naphthoquinones.

4. Pharmacology: Mechanisms of Action

Anti-inflammatory Mechanisms

Anti-inflammatory activity of the essential oil appears driven mainly by α-humulene, while antioxidant activity is provided by α-pinene and caryophyllene oxide. The essential oil possesses anti-inflammatory activity by inhibiting nitric oxide (NO) production. At the molecular level, parthenolide — also present in the closely related species Tanacetum parthenium — has been shown to exert anti-inflammatory effects primarily by inhibiting the NF-κB signaling pathway, though this specific mechanism has been most extensively studied in feverfew rather than tansy proper. Schinella et al. demonstrated that parthenolide was the main in vivo anti-inflammatory substance in T. vulgare. Flavonoids present in the plant could be, in part, responsible for these biological effects.

Antioxidant Mechanisms

Methanol extracts from T. vulgare showed antioxidant activity, probably due to the presence of phenolic compounds. The antioxidant activity found in tansy extract is supported by results reported in other studies and aligns with the traditional medicinal uses of the plant for conditions such as injury recovery, arthritis, and inflammatory processes.

Neurotoxic Mechanism of Thujone

Thujone has been shown to induce behavioral changes in mice, increase mortality rates, result in organ effects, and decrease the weights of various organs including the liver, spleen, thymus, kidneys, and lungs. The neurotoxicity of thujone is understood to involve disruption of GABA-A receptor function, which can produce the characteristic convulsive effects described in poisoning cases.

Antibacterial Mechanisms

The main compounds known for their antibacterial effects in tansy essential oil include α-thujone, β-thujone, eucalyptol, sabinene, chrysanthenone, camphor, linalool oxide acetate, cis-carveol, and trans-carveyl acetate. Essential oil from T. vulgare was active against both Escherichia coli and Staphylococcus aureus, with camphor and caryophyllene oxide being implicated in the antibacterial activity.

5. Scientific Evidence by Area of Use

5.1 Antimicrobial Activity

Evidence level: Preclinical (in vitro) only; no human clinical trials.

Most alcohol extracts of T. vulgare are reported to have biological effects including anti-inflammatory, antioxidant, and antibacterial properties. A 2017 in vitro study from the Université du Québec à Chicoutimi examined essential oil from tansy collected in northern Canada and assessed anti-inflammatory, antioxidant, antibacterial, and cytotoxic activities. Biological activities of the essential oil and its main constituents were evaluated in vitro. The major compounds were identified as camphor, borneol, and 1,8-cineole, and the oil possessed anti-inflammatory activity inhibiting NO production.

A 2023 PMC-published study investigated the antibacterial activity of tansy essential oil against drug-resistant ESKAPE pathogens. Evaluation was carried out using the Kirby-Bauer and binary microdilution methods on Gram-positive and Gram-negative MDR strains belonging to the ESKAPE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.). Tansy essential oil showed MIC values ranging from 62.5 to 500 μg/mL against the tested strains. Synergistic activity with different classes of antibiotics (penicillins, cephalosporins, carbapenems, monobactams, aminoglycosides, and quinolones) was also noted. The results demonstrate that tansy essential oil represents a promising lead for developing new antimicrobials active against MDR bacteria, alone or in combination with antibiotics.

Regarding bacteriostatic properties across extract types, hydroethanolic extract (40:60, v/v) and EOs of T. vulgare and T. balsamita exhibited bacteriostatic effects on a broad range of Gram-positive bacteria, displaying MIC values ranging from 1 to 16 mg/mL for crude extracts, and 0.5–8 μg/mL for EOs. The antimicrobial activity of methanol extracts was higher against Gram-positive bacteria.

Regarding antifungal activity, tansy EO showed strong activity against most tested fungi and was as efficient as bifonazole and ketoconazole. A PubMed-indexed study on ethyl acetate (EtOAc) extracts against Candida albicans found that the EtOAc extract alone disclosed moderate antifungal activity toward C. albicans after 24 hours (inhibition zone diameter = 20 mm) at a dose of 100 mg/mL, with the effect more pronounced when combining the extract (100 mg/mL) with 2% chlorhexidine (IZD values ranging from 30 to 32.7 mm), suggesting a synergistic effect.

All antimicrobial evidence is in vitro. No controlled human clinical trials have been published testing tansy as an antimicrobial agent.

5.2 Anti-inflammatory Activity

Evidence level: Preclinical (in vitro and animal studies); no human clinical trials.

Most alcohol extracts of T. vulgare are reported to have biological effects including anti-inflammatory, antioxidant, and antibacterial properties. Studies on rats and mice have found T. vulgare extracts to have anti-inflammatory properties. Flavonoids present in the plant could be, in part, responsible for these biological effects.

A seminal 1998 study published in the Journal of Pharmacy and Pharmacology investigated the anti-inflammatory components of South American T. vulgare. Using dichloromethane and methanol fractions applied to a mouse-ear oedema model induced by 12-O-tetradecanoylphorbol 13-acetate, the principles responsible for anti-inflammatory activity were identified as parthenolide (93% oedema inhibition at 0.5 mg/ear, ID50 = 0.18 μmol/ear) and the methoxyflavones jaceosidin (80% oedema inhibition at 0.5 mg/ear, ID50 = 0.50 μmol/ear), eupatorin, chrysoeriol, and diosmetin.

All anti-inflammatory evidence derives from in vitro models and rodent studies. No controlled human clinical trials exist specifically for tansy as an anti-inflammatory agent.

5.3 Anthelmintic (Antiparasitic) Activity

Evidence level: In vitro (strong) and early veterinary in vivo (promising); no human clinical trials.

The traditional use of tansy as an anthelmintic or vermifuge to expel parasitic worms from the digestive tract is well established, however this is no longer recommended due to the toxic constituent, thujone.

A 2023 PMC-published in vitro study examined tansy extracts against Trichostrongylidae nematodes in sheep. This study evaluated the in vitro ovicidal and larvicidal activity of extracts of tansy (Tanacetum vulgare L.) growing in Latvia on gastrointestinal nematodes (Trichostrongylidae) in sheep. The leaves and flowers of the tansy were extracted separately in 70%, 50%, and 30% ethanol and acetone. Six concentrations were prepared from each extract: 500 mg/mL, 200 mg/mL, 100 mg/mL, 50 mg/mL, 20 mg/mL, and 10 mg/mL. In vitro egg hatching test and micro-agar larval development test were performed. Extracts of tansy have strong larvicidal activity. The highest percentage of larvae inhibition for most of the extracts was 100%, but for egg inhibition it was 95.8% for the 200 mg/mL concentration of 50% acetone and 93.3% for the 500 mg/mL concentration of 50% ethanol leaf extracts. All tansy extracts had ovicidal and larvicidal activity against Trichostrongylidae in sheep.

Building on this in vitro evidence, a subsequent in vivo veterinary clinical study was conducted. Tanacetum vulgare (tansy), a traditionally used antiparasitic herb in Latvia, had shown in vitro efficacy but lacked in vivo delivery validation. The study aimed to evaluate the in vivo antiparasitic efficacy and safety of T. vulgare extract administered through novel intraruminal boluses and granules in naturally infected sheep. Thirty female Latvian Darkhead lambs (4–5 months; mean 35 ± 0.8 kg) were randomly assigned to five groups: two bolus groups, one granule group, and two controls (negative and positive).

No controlled human clinical trials have been conducted to evaluate tansy's anthelmintic efficacy in humans.

5.4 Diuretic Activity

Evidence level: Preclinical (animal studies confirming traditional use); no human clinical trials.

Although both caraway and tansy are well recognised in Moroccan traditional medicine as having a diuretic effect at a dose of 100 mg/kg, no scientific data had been published supporting the claimed ethnomedical use prior to controlled investigation. A ScienceDirect-published study evaluated this by orally administering aqueous extracts of tansy to male Wistar rats. Water extracts of Carum carvi and Tanacetum vulgare (100 mg/kg) or the reference drug furosemide (10 mg/kg) were administered orally to male Wistar rats, and urine output was quantitated at several time intervals after the dose. After single doses, urine output was significantly increased at all time points. In conclusion, water extracts of both Carum carvi and Tanacetum vulgare have strong diuretic action, confirming their ethnopharmacological use.

5.5 Antioxidant Activity

Evidence level: In vitro; no human clinical trials.

Research has characterized phenolic compounds (flavonoids, phenolic acids, and tannins) in T. vulgare and detected antioxidant activity using the DPPH assay. The main highlights support ethnomedicinal uses for wild T. vulgare through the integration of phenolic compounds as one of the value constituents of leaves and flowers. Experiments have confirmed antioxidant and antibacterial activities in tansy extracts, with the principal antioxidant contributors being phenolic acids such as chlorogenic acid and rosmarinic acid.

5.6 Cognitive Enhancement and Neuroprotection

Evidence level: Preliminary animal studies only; no human clinical trials.

Tanacetum vulgare L. has been traditionally applied as a remedy for headaches, rheumatism, digestion, respiratory and neurological problems, and other medical conditions. However, literature data on its effects on cognitive function are scarce. One study aimed to evaluate the effects of two doses of T. vulgare alcohol extract on cognitive functions, hippocampal brain-derived neurotrophic factor (BDNF) expression, and organ toxicity in rats. Rats were treated with T. vulgare 200 mg/kg (TV 200) and 1000 mg/kg (TV 1000) for 28 days. After one week of pre-treatment, animals were subjected to a series of tests. In the active avoidance test, only TV 200 improved learning and memory, while in the passive avoidance test, both doses facilitated these processes. In addition, the two doses enhanced spatial memory. In the elevated plus maze test, only the higher dose of TV 1000 resulted in anxiolytic-like behavior. Both doses of the extract significantly increased the hippocampal expression of BDNF. The authors suggested that increased neurotrophic factor expression could be one of the important mechanisms underlying the cognition-enhancing effects of T. vulgare extract.

These results are preliminary animal data and cannot be extrapolated to humans without further study.

5.7 Choleretic and Hepatoprotective Activity

Evidence level: Registered pharmaceutical use (Russia); limited published clinical data.

A purified complex extract of flavonoids and phenolcarbonic acids from tansy flowers, commercially known as Tanacechol®, is registered in Russia as a choleretic and spasmolytic agent for chronic cholecystitis and biliary dyskinesia. Studies on T. vulgare have also revealed vasorelaxant, diuretic, antiulcer, choleretic, and hepatoprotective properties. However, publications regarding the pharmacological effects and clinical trials of these tablets are far too limited to allow conclusions regarding its therapeutic potential.

5.8 Cytotoxic Activity

Evidence level: In vitro only; no human clinical trials.

Exposure to tansy extract has been reported to decrease the viability of breast cancer cell lines in a dose- and time-dependent manner. Cytotoxic activity against in vitro cultured cancer and healthy cell lines has been reported for eudesmanolides isolated from flowers of T. vulgare L. growing in Sicily. Methanol extracts of leaves and flowers exhibited a strong antiproliferative effect on HeLa cells. It has been shown that α,β-thujone (70% of α-thujone and 10% of β-thujone) also have anti-cancer effects against placental choriocarcinoma cells by inducing apoptosis via the mitochondrial-mediated intrinsic pathway. All cytotoxic findings are in vitro and not clinically validated.

5.9 Insect Repellent Activity

The oil obtained from T. vulgare is used by applying on skin as a repellent against insects and the common tick Ixodes ricinus. Tansy is also used as a companion plant, especially with cucurbits like cucumbers and squash, or with roses or various berries. It is thought to repel ants, cucumber beetles, Japanese beetles, squash bugs, and some kinds of flying insects. The insect-repellent properties are generally attributed to the volatile compounds in the essential oil, particularly thujone and related monoterpenes, but formal human clinical evidence for topical repellent efficacy is limited.

6. Body Systems and Health Areas Associated with Tansy

• Digestive system: Traditional use as a carminative, antispasmodic, anthelmintic, and choleretic; in vitro and animal evidence for antispasmodic and choleretic effects; registered pharmaceutical use in Russia for biliary conditions.
• Immune and inflammatory system: In vitro and animal evidence for anti-inflammatory activity mediated by parthenolide and methoxyflavones.
• Antimicrobial: In vitro evidence against Gram-positive and Gram-negative bacteria, and fungal pathogens including Candida albicans.
• Urinary system: Rat study evidence confirming traditional use as a diuretic at doses of 100 mg/kg.
• Reproductive system: Traditional emmenagogue and abortifacient use; not recommended for medicinal use due to toxicity risk.
• Nervous system: Preliminary rodent evidence for cognitive enhancement and BDNF upregulation; also, the primary site of toxicity (thujone-related neurotoxicity).
• Skin and external: Traditional topical use for arthropod infestations, joint pain, and skin conditions; essential oil applied as insect repellent.
• Hepatobiliary system: Choleretic and hepatoprotective activity reported in pharmacological studies; clinical application as Tanacechol® in Russia.

7. Dosage Forms and Reported Dosages

Dosages reported in the scientific and pharmacological literature are as follows:

• Traditional flower decoction (internal): The flowers of T. vulgare are recommended for internal administration at the dose of 1 tablespoon of the decoction (10 g in 200 mL of water), 3 times per day, as a choleretic and anthelmintic.
• Tanacechol® (standardized tablet): Tanacechol® tablets containing 0.05 g of a purified complex extract of flavonoids and phenolcarbonic acids are recommended for internal administration at the dose of 1–2 tablets, 3–4 times per day, for 20–30 days in patients with biliary system and liver diseases.
• Aqueous extract in rodent toxicity studies: For acute study, a lyophilized aqueous extract of tansy leaves was administered to mice in single doses of 0–13 g/kg given by gavage as well as intraperitoneal doses of 0–4.5 g/kg. In the chronic dose study, the extract was administered orally at doses of 0, 100, 300, and 600 mg/kg daily for 90 days to rats.
• Alcohol extract in cognitive studies (rodents): Rats were treated with T. vulgare 200 mg/kg (TV 200) and 1000 mg/kg (TV 1000) for 28 days.
• Aqueous extract in diuretic studies (rodents): Water extracts of Tanacetum vulgare (100 mg/kg) were administered orally to male Wistar rats.
• In vitro anthelmintic concentrations: Six concentrations were prepared from each tansy extract: 500 mg/mL, 200 mg/mL, 100 mg/mL, 50 mg/mL, 20 mg/mL, and 10 mg/mL for in vitro testing against nematode eggs and larvae.

No standardized human clinical dosages have been established in peer-reviewed literature for any indication.

8. Safety Considerations and Toxicology

Essential Oil Toxicity

The essential oil in the leaves, high in thujone, is toxic and causes convulsions; approximately 15–30 g can kill an adult human. Even the external use of the plant carries some risk of toxicity. Symptoms of tansy EO poisoning include severe gastritis, intense spasms and convulsions, liver and brain damage, and rapid and weak pulse.

Aqueous Extract Toxicity (Rodent Data)

The LD50 values for the lyophilized aqueous extract were lower for female mice (oral dose: 8.70 g/kg; intraperitoneal dose: 2.25 g/kg) than for male mice (oral dose: 11.30 g/kg; intraperitoneal dose: 3.25 g/kg). In the chronic study in rats, daily oral administration of the crude aqueous extract of tansy up to 600 mg/kg for 90 days did not result in death or significant changes in the biological (except for hypoglycemia) or hematological parameters. In the acute study in mice, the crude aqueous extract of tansy leaves caused dose-dependent general behavior adverse effects and mortality.

The extracts obtained from T. vulgare leaves have not been reported to have significant toxicity. In view of the dose consumed in traditional medicine, there is a wide margin of safety for the therapeutic use of the extracts of T. vulgare leaves. This distinction between the safety profile of aqueous leaf extracts (which contain minimal thujone) and the essential oil (which may contain high thujone concentrations) is pharmacologically significant.

Bulgarian EO Acute Toxicity

The Bulgarian essential oil was tested for single-dose acute toxicity on Wistar rats and was found to be non-toxic by oral administration. The mean lethal dose by intraperitoneal administration was LD50 i.p. = 14.9 g/kg body weight. No histopathological changes in the internal organs (kidney, liver, lung, heart) of the treated animals were observed. Note that this finding applies to a low-thujone Bulgarian chemotype and cannot be generalised to all essential oil chemotypes.

Tanacechol® Safety

The safety of Tanacechol® has been tested in rats, mice, dogs, and guinea pigs. This drug was not toxic, and no histopathological effects were detected after 90 days of administration in rats and dogs at the dose of 100 mg/kg. No allergenic effects were observed in guinea pigs.

Contact Dermatitis

Many tansy species contain a volatile oil which can cause contact dermatitis in sensitive individuals. If taken internally, toxic metabolites are produced as the oil is broken down in the liver and digestive tract.

Pregnancy and Reproductive Toxicity

Pregnant women are advised not to use this herb given its well-documented historical use as an emmenagogue and abortifacient. The uterine-stimulating properties associated with traditional use make it a contraindication in pregnancy.

Thujone-Related Neurotoxicity Risk

α-thujone has stronger neurotoxicity than β-thujone, and both can cause acute and chronic toxicity manifested by seizures of varying degrees. In spite of the popular use of tansy in traditional medicine and its potential for toxicity, systematic evaluation of its toxic effects is lacking. The critical safety distinction in current literature is between thujone-rich essential oil preparations (which pose documented toxicity risks) and aqueous leaf extracts (which do not contain significant thujone according to available studies).

Hypoglycemic Effects

In the chronic study in rats, an exception to the otherwise unremarkable hematological and biochemical findings was hypoglycemia observed at doses up to 600 mg/kg. This indicates a potential interaction with blood glucose regulation and hypoglycemic medications, warranting attention.

Allergenicity

As a member of the Asteraceae (Compositae) family, tansy shares potential cross-reactivity concerns common to the family, which includes other known allergenic species. Individuals with known sensitisation to other Asteraceae species — such as ragweed, chamomile, or feverfew — may be at elevated risk for allergic reactions to tansy preparations, though direct tansy-specific clinical allergy studies are limited in the current literature.

9. Regulatory and Commercial Status

A purified complex extract of flavonoids and phenolcarbonic acids from tansy flowers (Tanacechol®) is registered in Russia as a choleretic and spasmolytic agent for chronic cholecystitis and biliary dyskinesia. There is no current authorised medicinal use of tansy in the European Union, United States, or under major international pharmacopeial monographs for human therapeutic use. The essential oil, due to its thujone content, is subject to restrictions in food use in many jurisdictions; thujone is regulated as a food additive under EU regulations and by the FDA. Notwithstanding its history, current uses of this plant in teas, food, and medicine have now virtually disappeared in mainstream Western markets.

10. Summary of Evidence Strength

• Antimicrobial (antibacterial/antifungal): Multiple in vitro studies with consistent results; no human clinical trials. Evidence is preliminary.
• Anti-inflammatory: Rodent and in vitro studies confirming activity; active compounds identified. Evidence is preclinical.
• Anthelmintic: Strong in vitro data; early veterinary in vivo data; no human clinical trials. Evidence is preclinical to early veterinary.
• Diuretic: Single controlled animal study confirming traditional use. Evidence is preclinical.
• Choleretic: Registered pharmaceutical use (Tanacechol®) with supporting pharmacological data, but insufficient published clinical trial data to draw conclusions.
• Cognitive/neuroprotective: Single preliminary animal study. Evidence is very early and preliminary.
• Cytotoxic/anti-cancer: In vitro only; no clinical relevance established.
• Human clinical trials for any indication: None identified in the peer-reviewed literature.

References

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