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Comfrey |
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Comfrey (Symphytum officinale L.) is a perennial herb of the family Boraginaceae with a black, turnip-like root and large, hairy broad leaves that bears small bell-shaped white, cream, purple or pink flowers. It is native to Europe, growing in damp, grassy places, and is widespread throughout the British Isles on river banks and ditches. The common name comfrey is from the Latin confirmare meaning to join together. The herb is named after its traditional folk use in compress and poultice preparations to speed the healing of fractures, broken bones, bruises, and burns. Also known as common comfrey, blackwort, boneset, bruisewort, gum plant, healing herb, salsify, and slippery root, this erect-growing herb can reach a height of one meter. The rootstock is fleshy, branched, and white internally. The plant produces an angular hairy stem which grows up to three feet in height, branching only near the top. It bears large, oblong, lanceolate leaves, which are green, rough, and covered with short hairs. The leaves and flowering tops are harvested during the summer. The root has a black exterior and fleshy whitish interior filled with juice. The root is harvested in the spring or fall when the allantoin levels are the highest. There are about 25 species of the herb, including prickly comfrey (S. asperum) and Russian comfrey. In Russian medicine, the herb is considered poisonous when used excessively. |
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Active constituents and clinical pharmacology of comfrey |
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| Comfrey contains allantoin, rosmarinic acid, symphytine, echimidine, isobauerenol, -sitosterol, tannins, lasiocarpine, phytosterols, triterpenoid (isobauerenol), phenolic compounds (including caffeic, chlorogenic and lithospermic acids), pyrrolizidine alkaloids, inulin, and vitamin B12. Comfrey is also an excellent source of potassium, phosphorus, calcium, and nitrogen. Allantoin promotes wound healing and tissue regeneration. Allantoin is able to diffuse through the skin and tissues. Symphytum is an excellent remedy in the treatment of chronic and varicose ulcers. Comfrey is also known to contain gamma linoleic acid, an essential fatty acid used by the body to maintain cell functions, to alter cholesterol levels, and as a precursor for hormones. Tannins have astringent properties. The pyrrolizidine alkaloids are potentially toxic, known to cause hepatotoxicity and to be carcinogenic. |
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Medicinal uses and health benefits of comfrey |
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| Comfrey is one of the most valuable herbs because it has beneficial effects on all parts of the body, and can be used as an overall tonic. Comfrey has been used to treat a wide variety of ailments ranging from bronchial problems, broken bones, sprains, arthritis, gastric and varicose ulcers, severe burns, acne and other skin conditions. Comfrey is an effective remedy for coughs, ulcers, healing broken bones, sprains and asthma. Comfrey promotes healthy skin with its mucilage content that moisturizes and soothes, while the allantoin promotes cell proliferation. Comfrey helps in the calcium-phosphorus balance by promoting strong bones and healthy skin. It helps promote the secretion of pepsin and is a general aid to digestion. Comfrey may be used externally to speed wound-healing and guard against scar tissue development incorrectly. Comfrey has been prepared as a poultice or compress with healing properties for blunt injuries, fractures, swollen bruises, boils, carbuncles, varicose ulcers, and burns. Externally, comfrey leaves can also promote the healing of minor burns, eczema, and psoriasis, soothe bee stings and spider bites, and treat skin staph infections and athlete's foot. Comfrey root's mucilage helps heal ulcers by coating them and destroying amoebic parasites. Comfrey, taken internally as a tea or expressed juice, has been used for stomach upset, stomach ulcers, hemorrhoids, and diarrhea. |
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Side effects, precautions, interactions |
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| Oral comfrey products have been restricted by the FDA. Comfrey contains toxic substances (hepatotoxic pyrrolidizine alkaloids) that can cause severe liver damage and possibly even death. This alkaloid is found primarily in Russian comfrey and prickly comfrey rather than the common comfrey. Comfrey and comfrey-containing products should never be ingested. Comfrey is considered relatively safe if used only as a topical preparation on unbroken skin (free of cuts or open wounds). However, using comfrey on dirty or deep wounds should be avoided, because the rapid healing properties of the allantoins may trap dirt or pus, and lead to the formation of abscesses. Comfrey may be contraindicated in patients on dietary potassium restrictions. The antituberculous activity of comfrey may potentiate the adverse effect of other antituberculous drugs, especially ethionamide. Comfrey preparations should not be used for more than four weeks. Pregnant and breastfeeding women should not use comfrey products under any circumstances. |
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