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Comfrey

Comfrey
© Sertürner Bildarchiv

Botanical name

Common Comfrey - Symphytum officinale L.

Family

Borage family (Boraginaceae)

Useful information about the plant

Comfrey is native to Eurasia and stretches east to Central Asia. It grows in moist meadows, ditches and banks. In Europe it grows everywhere except for in the Iberian Peninsula, in southern Italy and in Greece; its northern border is Great Britain and southern Scandinavia.
The genus name Symphytum is derived from the Greek "syn" (= together) and "phyo" (= growth), resulting in the Greek word: "symphytos" (= grown together). Thus meaning the growing together of wounds or even bone, i.e. a wound healing agent. Comfrey is a very old medicinal plant, which is illustrated in the epithet officinale because officinalis means "used in pharmacies," derived from the "officina", the sales room of a pharmacy. Comfrey grows 50 to 100m high and is anchored by a thick fleshy taproot up to 30cm deep in the earth. It is a half-rosette shrub with a branched, very bristly stem. The leaves are oval, lance shaped, tapered, the upper leaves narrowing into a winged leaf stalk running down to the far end of the stalk. The leaf veins are also hairy and rough. In the axils of the upper leaves are the purple or red-violet (also yellow-white), bell-shaped, nodding flowers are in thick blooded double wrapping. Its bells have calyx teeth, the petals form an externally very hairy tube. The flowering period is May to July.

Medicinally used plant parts (drug)

The dried roots are used. The commercial drug comes from crops. The dried herb of S. x uplandicum Nym. which is imported from Eastern European countries is used medicinally.

Ingredients of the drug

Comfrey root and the comfrey herb contain tannins, mucilage, caffeic acid derivatives (including rosmarinic acid) allantoin and pyrrolizidine. Since the latter are toxic to the liver, crops low in pyrrolizidine are used to make finished medicinal products.

Descriptions of the quality

The quality of comfrey root is not defined in the pharmacopoeia (Ph. Eur., DAB, DAC).

Medical Application

Recognised medical use

Externally for bruises, strains and sprains (Commission E, ESCOP), ESCOP lists as additional application areas: arthritis, tendonitis and epicondylitis. Through clinical trials the following areas of application were documented (approval): For painful muscle and joint pains, bruises, strains, sprains (after the acute phase) and to promote blood circulation.

Traditional use

Comfrey has no listing as traditional medicinal use (§ 109a).

Medicinal herbal preparations in finished drug products

Symphytum officinale - Root

Symphytum uplandicum - Herb

Dosage

Prepared drugs: see packaging leaflet;
Tea infusion: For external use only! Several times a day as a warm compress with a decoction of comfrey root / comfrey herb or the powdered root applied as a warm pulp. The administered dose per day may not contain more than 100 micrograms of pyrrolizidine alkaloid.

Preparation of a tea infusion

Boil 5 to 10g coarsely powdered drug in 100ml of water then strain after 15 min. A warm pulp is prepared by stirring with a little hot water.

Advice

Only apply to intact skin! Comfrey preparations should not be used (pyrrolizidine alkanoi) during pregnancy and while breast-feeding and in children under 2 years old.
Sincea mutagenic effect could be observed in various test systems for the Symphytum-Pyrrolizidine, as a precaution, comfrey preparations may only be applied to intact skin.
Although the pyrrolizidine alkaloid does not enter the bloodstream when applied to intact skin, Comfrey should not be applied for longer than 4 to 6 weeks per year. The extracts processed in the finished medicinal product are however usually made with a special process in which the content of pyrrolizidines is significantly reduced. For such products, there is no limitation in the application period.

Side effects

None known.

Interactions

None known.

References

Drug monographs

Commission E, ESCOP

Further reading

Wichtl: Teedrogen und Phytopharmaka, pg. 644
Schilcher: Leitfaden Phytotherapie, pg. 54
Van Wyk: Handbuch der Arzneipflanzen, pg. 314

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