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Comfrey

Uses

Common names:

Knitbone

Botanical names:

Symphytum officinale

Parts Used & 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.

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Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.

For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

3 Stars Reliable and relatively consistent scientific data showing a substantial health benefit.

2 Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

This supplement has been used in connection with the following health conditions:

Used for	Why
2 Stars Sprains and Strains Apply an ointment containing 35% herbal extract	Comfrey is widely used in traditional medicine as a topical application to help heal wounds. Reference Comfrey is also widely used in traditional medicine as a topical application to help heal wounds.⁴ In a study of people with acute ankle sprains, topical application of an ointment four times a day containing a comfrey extract was at least as effective as, and possibly more effective than, a topically applied anti-inflammatory drug (Reference diclofenac). The comfrey ointment was a proprietary product that contained 35% comfrey extract.⁵
1 Star Bruising Refer to label instructions	Comfrey is widely used in traditional medicine as a topical application to help heal wounds and may be beneficial for bruises. Reference Comfrey is also widely used in traditional medicine as a topical application to help heal wounds.⁶
1 Star Conjunctivitis and Blepharitis Refer to label instructions	Comfrey has been traditionally used to treat eye inflammation. Several herbs have been traditionally used to treat eye inflammation. Examples include Reference calendula, Reference eyebright, Reference chamomile, and Reference comfrey. None of these herbs has been studied for use in conjunctivitis or blepharitis. As any preparation placed on the eye must be kept sterile, topical use of these herbs in the eyes should only be done under the supervision of an experienced healthcare professional.
1 Star Cough Refer to label instructions	Comfrey (the above-ground parts, not the roots) has a long history of use for relieving coughs. The mucilage of Reference slippery elm gives it a soothing effect for coughs. Reference Usnea also contains mucilage, which may be helpful in easing irritating coughs. There is a long tradition of using Reference wild cherry syrups to treat coughs. Other traditional remedies to relieve coughs include Reference bloodroot, Reference catnip, Reference comfrey (the above-ground parts, not the root), Reference horehound, Reference elecampane, Reference mullein, Reference lobelia, Reference hyssop, Reference licorice, Reference mallow, (Malvia sylvestris), Reference red clover, Reference ivy leaf, Reference pennyroyal (Hedeoma pulegioides, Mentha pulegium), Reference onion, (Allium cepa), and Reference plantain (Plantago lanceolata, P. major). None of these has been investigated in human trials, so their true efficacy for relieving coughs is unknown.
1 Star Peptic Ulcer Refer to label instructions	Comfrey has history of traditional use for treating gastrointestinal problems, including stomach ulcers. Reference Comfrey has a long tradition of use as a topical agent for improving healing of Reference wounds and Reference skin ulcers.⁷ ^{, 8} It is also used for people with gastrointestinal problems, including stomach ulcers, though these traditional uses have yet to be tested in scientific studies. People should only use comfrey preparations made from the leaves and avoid those made from the root.
1 Star Wound Healing Refer to label instructions	Comfrey has anti-inflammatory properties that may decrease bruising and help heal wounds when the herb is applied topically. Reference Comfrey has anti-inflammatory properties that may decrease bruising when the herb is applied topically.⁹ Comfrey is also widely used in traditional medicine as a topical application to help heal wounds.¹⁰ Reference Witch hazel can also be used topically to decrease inflammation and to stop bleeding.¹¹ Native Americans used poultices of witch hazel leaves and bark to treat wounds, insect bites, and ulcers.¹² Reference Horsetail can be used both internally and topically to decrease inflammation and promote wound healing.¹³

Traditional Use (May Not Be Supported by Scientific Studies)

Comfrey has a long history of use as a topical agent for treating Reference wounds, skin ulcers, thrombophlebitis, Reference bruises, and Reference 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 Reference conjunctivitis. Internally, it was used to treat gastrointestinal problems, such as stomach Reference ulcers, 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 It Works

Common names:

Knitbone

Botanical names:

Symphytum officinale

How to Use It

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.¹⁴ 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.

Interactions

Common names:

Knitbone

Botanical names:

Symphytum officinale

Interactions with Supplements, Foods, & Other Compounds

At the time of writing, there were no well-known supplement or food interactions with this supplement.

Interactions with Medicines

As of the last update, no reported interactions between this supplement and medicines. It is possible that unknown interactions exist. If you take medication, always discuss the potential risks and benefits of adding a new supplement with your doctor or pharmacist.

The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a supplement with your doctor or pharmacist.

Side Effects

Common names:

Knitbone

Botanical names:

Symphytum officinale

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.¹⁵ ^{, 16} Fresh young leaves contain higher amounts (up to 16 times more than mature leaves) and should be avoided.¹⁷ 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.¹⁸ 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.¹⁹

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.

Related Information

Reference What Are Depletions & Interactions?

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 R. Herbal Medicine. Gothenburg, Sweden: Ab Arcanum and Beaconsfield, UK: Beaconsfield Publishers Ltd, 1988, 342.

5. Predel HG, Giannetti B, Koll R, et al. Efficacy of a comfrey root extract ointment in comparison to a diclofenac gel in the treatment of ankle distortions: results of an observer-blind, randomized, multicenter study. Phytomedicine2005;12:707–14.

6. Weiss R. Herbal Medicine. Gothenburg, Sweden: Ab Arcanum and Beaconsfield, UK: Beaconsfield Publishers Ltd, 1988, 342.

7. Mills SY. Out of the Earth: The Essential Book of Herbal Medicine. New York: Viking Arkana, 1991, 544–7.

8. Weiss RF. Herbal Medicine. Gothenburg, Sweden: Ab Arcanum and Beaconsfield, UK: Beaconsfield Publishers Ltd, 1988, 334–5.

9. Blumenthal M, Busse WR, Goldberg A, et al. The Complete German Commission E Monographs. Therapeutic Guide to Herbal Medicines. Austin, Texas: American Botanical Council, 1998, 115–6.

10. Weiss R. Herbal Medicine. Gothenburg, Sweden: Ab Arcanum and Beaconsfield, UK: Beaconsfield Publishers Ltd, 1988, 342.

11. Blumenthal M, Busse WR, Goldberg A, et al. The Complete German Commission E Monographs. Therapeutic Guide to Herbal Medicines. Austin, Texas: American Botanical Council, 1998, 231.

12. Duke JA. CRC Handbook of Medicinal Herbs. Boca Raton, FL: CRC Press, 1985, 221.

13. Blumenthal M, Busse WR, Goldberg A, et al. The Complete German Commission E Monographs. Therapeutic Guide to Herbal Medicines. Austin, Texas: American Botanical Council, 1998, 150–1.

14. Weiss RF. Herbal Medicine. Gothenburg, Sweden: Ab Arcanum and Beaconsfield, UK: Beaconsfield Publishers Ltd., 1988, 334–5.

15. Mills SY. Out of the Earth: The Essential Book of Herbal Medicine. New York: Viking Arkana, 1991, 544–7.

16. Winship KA. Toxicity of comfrey. Adverse Drug React Toxicol Rev 1991;10:47–59 [review].

17. Foster S. Herbal Renaissance. Salt Lake City: Gibbs-Smith Publisher, 1993, 74–8.

18. Foster S. Herbal Renaissance. Salt Lake City: Gibbs-Smith Publisher, 1993, 74–8.

19. Foster S, Tyler VE. Tyler’s Honest Herbal. New York: Haworth Herbal Press, 1999, 121–6.

Last Review: 11-07-2012

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The information presented in Aisle7 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 June 2013.

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