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© Martin Wall
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Botanical name: Symphytum officinale
Common names: Knitbone, Boneset
Parts used and where grown
The leaf and root of comfrey have been employed medicinally for centuries. Originally from
Europe and western Asia, it is now also grown in North America.
Comfrey has been used in
connection with the following conditions (refer to the individual
health concern for complete information):
Historical or traditional use (may
or may not be supported by scientific studies)
Comfrey has a long history of use as a topical agent for treating wounds, skin ulcers, thrombophlebitis, bruises, and sprains
and strains.1 2 Comfrey was used by herbalists to promote more rapid
repair of broken bones, hence the common names boneset and knitbone. Topically, comfrey was
also used to treat minor skin irritations and inflammation. It has also been used as a wash or
topical application for eye irritations and for treating conjunctivitis. Internally, it was used to treat
gastrointestinal problems, such as stomach ulcers
and inflammatory bowel disease, and lung
problems.
Active constituents: Mucilage and allantoin are considered the major constituents in
comfrey responsible for the herbs soothing and anti-inflammatory actions.3
How much is usually taken?
Fresh, peeled root or dried root, approximately 3.5 ounces (100 grams), is simmered in 1
pint (500 ml) of water for ten to fifteen minutes to prepare comfrey for topical
use.4 Cloth or gauze is soaked in this liquid, then applied to the skin for at
least 15 minutes. Fresh leaves can be ground up lightly and applied directly to the skin.
Alternatively, creams or ointments made from root or leaf can be applied. All topical
preparations should be applied several times per day.
Due to variations in pyrrolizidine alkaloid content, root preparations are unsafe for
internal use unless they are guaranteed pyrrolizidine-free. Although comfrey root tea has been
used traditionally, the danger of its pyrrolizidine alkaloids is significant. Therefore,
comfrey root and young leaf preparations should not be taken internally.
Are there any side effects or interactions?
Comfrey contains potentially dangerous compounds known as pyrrolizidine alkaloids. The
roots contain higher levels of these compounds and mature leaves contain very little, if any,
of these alkaloids.5 6 Fresh young leaves contain higher amounts (up to
16 times more than mature leaves) and should be avoided.7 Other related forms, such
as Russian comfrey (Symphytum uplandicum) and prickly comfrey (S.
asperum), are sometimes available or mistakenly sold as regular comfrey but contain
higher levels of these alkaloids.8 Several cases of people who developed liver
disease or other serious problems from taking capsules or tea of comfrey have been reported
over the years.9
Most comfrey products do not list their pyrrolizidine alkaloid content on the label.
Therefore, it is best to avoid internal use of products made from comfrey root or young leaves
altogether.
At the time of writing, there were no well-known drug interactions
with comfrey.
Special United Kingdom considerations
Comfrey for internal use is only available as an herbal tea, unless prescribed by a
Medicinal Herbalist. People should consult with a qualified herbalist for other forms of this
herb.
References
1. Mills SY. Out of the Earth: The Essential Book of Herbal
Medicine. New York: Viking Arkana, 1991, 544–7.
2. Weiss RF. Herbal Medicine. Gothenburg, Sweden: Ab Arcanum and
Beaconsfield, UK: Beaconsfield Publishers Ltd., 1988, 334–5.
3. Duke JA. Handbook of Phytochemical Constituents of GRAS Herbs and
Other Economic Plants. Boca Raton, FL: CRC Press, 1992.
4. Weiss RF. Herbal Medicine. Gothenburg, Sweden: Ab Arcanum and
Beaconsfield, UK: Beaconsfield Publishers Ltd., 1988, 334–5.
5. Mills SY. Out of the Earth: The Essential Book of Herbal
Medicine. New York: Viking Arkana, 1991, 544–7.
6. Winship KA. Toxicity of comfrey. Adverse Drug React Toxicol
Rev 1991;10:47–59 [review].
7. Foster S. Herbal Renaissance. Salt Lake City: Gibbs-Smith
Publisher, 1993, 74–8.
8. Foster S. Herbal Renaissance. Salt Lake City: Gibbs-Smith
Publisher, 1993, 74–8.
9. Foster S, Tyler VE. Tyler’s Honest Herbal. New York:
Haworth Herbal Press, 1999, 121–6.
Copyright © 2004 Healthnotes, Inc. All rights reserved.
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The information presented in Healthnotes is for informational
purposes only. It is based on scientific studies (human, animal, or in vitro),
clinical experience, or traditional usage as cited in each article. The results reported may
not necessarily occur in all individuals. For many of the conditions discussed, treatment with
prescription or over-the-counter medication is also available. Consult your doctor,
practitioner, and/or pharmacist for any health problem and before using any supplements or
before making any changes in prescribed medications. Information expires March 2005.
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Reliable and relatively consistent scientific data showing a substantial health benefit.
Contradictory, insufficient, or preliminary
studies suggesting a health benefit or minimal health benefit.
