Synonyms
Doronicum arnica Desf., D. montanum Lam

Description
A perennial herb, 20–50 cm high. Aerial portion consists of a basal rosette of entire oblanceolate leaves up to 17 cm long, five to seven veins, from the centre of which projects an erect, simple, glandular hairy stem up to 0.6 m high. Stem bears two to four pairs of cauline leaves, ovate, elliptic-oblong, lanceolate or oblanceolate, with rounded or rounded-toothed apex and clothed with numerous nonglandular and glandular hairs, up to 16 cm long and 5 cm wide. Peduncles, one to three, bearing alternate bracteoles, extending from the uppermost pair of cauline leaves; glandular–puberulent, each terminating in a hemispherical or turbinate capitulum bearing orange-yellow flowers, which are tubular. Fruits, black to brown, five-ribbed, with a bristle tuft of hairs

Plant material used
dried flower heads

Chemical assays
Contains not less than 0.40% of total sesquiterpene lactones calculated as helenalin tiglate, determined by high-performance liquid chromatography

Major chemical constituents
The major constituents include the essential oil (0.5%), fatty acids (content not specifi ed), thymol (content not specifi ed), pseudoguaianolide sesquiterpene lactones (0.2–0.8%) and fl avonoid glycosides (0.2–0.6%). The primary sesquiterpene lactones are helenalin, 11α,13-dihydrohelenalin and their fatty acid esters. Flavonoids include glycosides and/or glucuronides of spinacetin, hispidulin, patuletin and isorhamnetin, among others

Medicinal uses
Uses supported by clinical data
None.

Uses described in pharmacopoeias and well established documents
As a topical counterirritant for treatment of pain and infl ammation resulting from minor injuries and accidents, including bruises, ecchymoses, haematomas and petechiae. Treatment of infl ammation of the oral mucous membranes, insect bites and superfi cial phlebitis.

Uses described in traditional medicine
Treatment of indigestion, cardiovascular disease, and rheumatism. As an emmenagogue.

Proven pharmacological activity
Animal studies
Analgesic and anti-inflammatory, Antioxidant, Antitumour, Choleretic, Uterine stimulant

Adverse reactions
Numerous cases of dermatitis of toxic or allergic origin have been reported, usually following prolonged, external application of a tincture of Flos Arnicae. The compounds responsible for the hypersensitivity reaction are the sesquiterpene lactones helenalin and helenalin acetate. Cross-reactivity to other Asteraceae flowers has been reported. The flower heads are irritant to the mucous membranes and ingestion may result in gastroenteritis, muscle paralysis (voluntary and cardiac), an increase or decrease in pulse rate, heart palpitations, shortness of breath and death. A fatal case of poisoning following the ingestion of 70.0 g of a tincture of the fl ower heads has been reported. A case of severe mucosal injuries following the misuse of an undiluted mouth rinse with a 70% alcohol content, which also contained oil of peppermint and Flos Arnicae, has been reported

Contraindications
Flos Arnicae is used in traditional systems of medicine as an emmenagogue, and its safety during pregnancy and nursing has not been established. Therefore, in accordance with standard medical practice, the fl ower heads should not be administered to pregnant or nursing women. Flos Arnicae is also contraindicated in cases of known allergy to Arnica or other members of the Asteraceae (Compositae).

Warnings
A fatal case of poisoning following the ingestion of 70.0 g of a tincture of Flos Arnicae has been reported. Internal use of Flos Arnicae or extracts of the fl ower heads is not recommended. For external use only. Do not apply to open or broken skin. Keep out of the reach of children.

Precautions
General
Avoid excessive use. Chronic, frequent external applications may induce allergy-related skin rashes with itching, blister formation, ulcers and superfi cial necrosis. Prolonged treatment of damaged or injured skin or indolent leg ulcers may induce the formation of oedematous dermatitis with the formation of pustules.

Carcinogenesis, mutagenesis, impairment of fertility
Helenalin has cytotoxic effects in vitro (see Experimental pharmacology). However, in the Salmonella/microsome assay, helenalin was not mutagenic in S. typhimurium strains TA102, TA98 or TA100 at concentrations of up to 30 µg/ml.

Pregnancy: teratogenic effects
Intraperitoneal administration of 6.0–20.0 mg/kg bw of helenalin was not teratogenic in mice.

Pregnancy: non-teratogenic effects
See Contraindications.

Nursing mothers
See Contraindications.

Paediatric use
See Warnings. For external use only. Do not apply to abraded or broken skin.

Other precautions
No information available on precautions concerning drug interactions; or drug and laboratory test interactions.

Dosage forms
Dried flower heads and other galenical preparations. Store protected from light and moisture.

Posology
(Unless otherwise indicated)
For external applications only, apply undiluted externally on the affected area two or three times daily: infusion for compresses, 2 g of Flos Arnicae per 100 ml water; tincture for compresses, one part Flos Arnicae to 10 parts 70% ethanol; mouth rinse, 10-fold dilution of tincture, do not swallow; ointment, 20–25% tincture of Flos Arnicae or not more than 15% essential oil