Richard's Whole Foods  
10% Off Register online today and receive 10% off your next in-store purchase.
Your E-mail:     
Healthy Recipes Reference Library Store Specials About Us Friday, May 05, 2006
Search Site
Reference Library
Sign In
My Account
Contact Us
Shopping Cart

Table of Contents > Herbs > Comfrey
Botanical Name:  Symphytum officinale
Common Names:  Knitbone
Plant Description
What's It Made Of?
Available Forms
How to Take It
Possible Interactions
Supporting Research


Comfrey (Symphytum officinale) has been traditionally used to treat wounds and to reduce the inflammation associated with sprains and broken bones. The roots and leaves of comfrey contain allantoin, a substance that promotes wound healing and tissue regeneration. Comfrey ointments were often applied to the surface of the skin to heal bruises as well as pulled muscles and ligaments, fractures, sprains, and strains. Some traditional healers also used comfrey leaves to reduce inflammation, treat gout, and heal superficial blood clots in the legs (called thrombophlebitis).

Despite these beneficial effects, reports began to emerge in the 1980s that internal consumption of comfrey may be hazardous to the health. Laboratory studies revealed that comfrey contains dangerous substances called pyrrolizidine alkaloids that are highly toxic to the liver. Animal studies found that consumption of comfrey may lead to a potentially life-threatening condition called hepatic veno-occlusive disease (HVOD) in which the blood vessels around the liver become blocked. If left untreated, HVOD can lead to complete liver failure, even death. Outbreaks of HVOD began to appear in Europe and the United States and researchers gradually discovered that these outbreaks were often linked to ingestion of oral comfrey products.

Echimidine is one of the most toxic pyrrolizidine alkaloids. Dangerously high levels of this alkaloid have been found in both prickley comfrey (Symphytum asperum) and Russian comfrey (Symphytum uplandicum), close relatives of the common comfrey plant. While common comfrey has been the preferred source of comfrey herbal products, some preparations sold in the United States and Europe may have been unknowingly contaminated with Russian and prickley comfrey. This is because common, Russian, and prickley comfrey are very similar in appearance and collectors who harvest raw plant material are not always able to distinguish between the different species.

Based on reports of HVOD in the United States and abroad, the U.S. Food and Drug Administration (FDA) recommended in July of 2001 that dietary supplement manufacturers immediately remove all comfrey-containing products from the market. The FDA cited evidence that the pyrrolizidine alkaloids are not only toxic to the liver, but possibly other tissues in the body as well. They also cited evidence that these substances may even potentially cause cancer. In addition to the United States, countries including the United Kingdom, Australia, Canada, and Germany have banned the sale of products containing comfrey. Other countries permit use of this herb only under a doctor's prescription.

Plant Description

Comfrey is a perennial herb that originated in Europe and temperate parts of Asia. Fond of moist soils, comfrey has an erect and stiff-haired stem, and it grows to a height of 20 to 120 cm. Its flowers are dull purple, violet, or whitish, and densely arranged in clusters. The wrinkly and hairy leaves are oblong, and often differ in appearance depending upon their position on the stem: the lower leaves are broad at the base and tapered at the ends while the upper leaves are broad throughout and narrowed only at the ends. The slimy roots show a horn-like appearance when dried. The root has a black exterior and fleshy whitish interior filled with juice.

Comfrey preparations are made from the leaves or other parts of the plant grown above the ground. Some preparations were also made from the roots, but roots contain up to 16 times the amount of pyrrolizidine alkaloids and are therefore more likely to cause poisoning.

What's It Made Of?

Comfrey contains allantoin, rosmarinic acid, and vitamin B12. It also contains poisonous compounds called pyrrolizidine alkaloids, which are highly concentrated in the roots of the comfrey plant. In fact, the roots contain levels of pyrrolizidine alkaloids that are roughly 10 to 16 times higher than the mature leaves.

Available Forms

Oral comfrey products have been restricted by the FDA, but topical preparations are still available in the United States.

Comfrey ointments (containing 5% to 20% comfrey), creams, poultices, and liniments are made from the fresh or dried herb, leaf, or root of comfrey species. Use only products made from leaves of common comfrey.

Be sure to buy comfrey preparations from established companies with good reputations, and who distribute their products through trustworthy and knowledgeable establishments. Whenever possible, select products with guaranteed potency or standardized extracts. Follow dosage recommendations on the label.

How to Take It


Children should never ingest comfrey or comfrey-containing products for any reason.

There are no known scientific reports on the pediatric use of topical comfrey ointments or creams. Therefore, it is not currently recommended for children.


Adults should never ingest comfrey or any comfrey-containing products.

Use only herb and leaf ointments, creams, and other topical preparations. Use only the amount recommended on the label and never more than this amount. Comfrey remedies should not be used for more than four to six weeks in any given year.


Comfrey contains toxic substances that can cause severe liver damage and possibly even death. For this reason, comfrey and comfrey-containing products should never be ingested. The main symptom you would feel if experiencing liver damage from comfrey is abdominal pain just below the right side of the rib cage because the liver enlarges from HVOD.

Because of the potential for side effects and interactions with medications, even topical comfrey preparations should be taken only under the supervision of a knowledgeable healthcare provider.

Comfrey is considered relatively safe if used only as a topical preparation on unbroken skin (free of cuts or open wounds).

Pregnant and breastfeeding women should not use comfrey products under any circumstances.

Possible Interactions

There are no known scientific reports of interactions between comfrey and conventional medications.

Supporting Research

Blumenthal M, Busse WR, Goldberg A, et al., ed. The Complete German Commission E Monograph; Therapeutic Guide to Herbal Medicines. Boston. Mass: Integrative Medicine Communications; 1998:115-116.

Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications; 1998:63.

Cirigliano M, Sun A. Advising patients about herbal therapies. JAMA. 1998;280(18):1565-1566.

Federal Trade Commission. Latest FTC case in "Operation Cure.All" focuses on safety risks of comfrey products promoted via Internet. Accessed at on July 9, 2001.

Foster S, Tyler VE. Tyler's Honest Herbal. 4th ed. New York: The Haworth Herbal Press; 1999:121-125.

Gruenwald J, Brendler T, Jaenicke C, eds. PDR for Herbal Medicines. 2nd ed. Montvale, NJ: Medical Economics Co; 2000:212-213.

Miller LG. Herbal medicinals: selected clinical considerations focusing on known or potential drug-herb interactions. Arch Intern Med. 1998;158(20):2200-2211.

Miskelly FG, Goodyer LI. Hepatic and pulmonary complications of herbal medicines. Postgrad Med J. 1992;68:935-936.

Newall CA, Anderson LA, Phillipson JD. eds. Herbal Medicines: A Guide for Health-care Professionals. London: Pharmaceutical Press; 1996:87-89.

Ridker PM, Ohkuma S, McDermott WV, Trey C, Huxtable RJ. Hepatic venocclusive disease associated with the consumption of pyrrolizidine-containing dietary supplements. Gastroenterology. 1985;(88):1050-1054.

Schulz V, Hänsel R, Tyler VE. Rational Phytotherapy: A Physician's Guide to Herbal Medicine. 3rd ed. Berlin: Springer; 1998:262.

Stickel F, Seitz HK. The efficacy and safety of comfrey. Public Health Nutr. 2000;3(4A):501-508.

U.S. Food and Drug Administration Center for Food Safety and Applied Nutrition. July 6, 2001. FDA advises dietary supplement manufacturers to remove comfrey products from the market. Accessed at on March 21, 2002.

U.S. Food and Drug Administration Center for Food Safety and Applied Nutrition. 1993. Illnesses and injuries associated with the use of selected dietary supplements. Accessed at on March 21, 2002.

Weston CFM, Cooper BT, Davies JD, et al. Veno-occlusive disease of the liver secondary to ingestion of comfrey. Br Med J. 1987;295:183.

Yeong ML, Swinburn B, Kennedy M, Nicholson G. Hepatic veno-occlusive disease associated with comfrey ingestion. J Gastroenterol Hepatol. 1990;5(2):211-214.

Review Date: April 2002
Reviewed By: Participants in the review process include: Jacqueline A. Hart, MD, Department of Internal Medicine, Newton-Wellesley Hospital, Harvard University and Senior Medical Editor Integrative Medicine, Boston, MA; Gary Kracoff, RPh (Pediatric Dosing section February 2001), Johnson Drugs, Natick, MA; Steven Ottariono, RPh, Veteran's Administrative Hospital, Londonderry, NH; R. Lynn Shumake, PD (April 1999), Director, Alternative Medicine Apothecary, Blue Mountain Apothecary & Healing Arts, University of Maryland Medical Center, Glenwood, MD; David Winston, Herbalist (April 1999), Herbalist and Alchemist, Inc., Washington, NJ; Tom Wolfe, P.AHG (April 1999), Smile Herb Shop, College Park, MD. All interaction sections have also been reviewed by a team of experts including Joseph Lamb, MD (July 2000), The Integrative Medicine Works, Alexandria, VA;Enrico Liva, ND, RPh (August 2000), Vital Nutrients, Middletown, CT; Brian T Sanderoff, PD, BS in Pharmacy (March 2000), Clinical Assistant Professor, University of Maryland School of Pharmacy; President, Your Prescription for Health, Owings Mills, MD; Ira Zunin, MD, MPH, MBA (July 2000), President and Chairman, Hawaii State Consortium for Integrative Medicine, Honolulu, HI.

Copyright © 2004 A.D.A.M., Inc

The publisher does not accept any responsibility for the accuracy of the information or the consequences arising from the application, use, or misuse of any of the information contained herein, including any injury and/or damage to any person or property as a matter of product liability, negligence, or otherwise. No warranty, expressed or implied, is made in regard to the contents of this material. No claims or endorsements are made for any drugs or compounds currently marketed or in investigative use. This material is not intended as a guide to self-medication. The reader is advised to discuss the information provided here with a doctor, pharmacist, nurse, or other authorized healthcare practitioner and to check product information (including package inserts) regarding dosage, precautions, warnings, interactions, and contraindications before administering any drug, herb, or supplement discussed herein.

  Uses of this Herb
Sprains and Strains
  Herbs with Similar Uses
View List by Use
  Drugs that Interact
  Herbs with Similar Side Effects
View List by Side Effect
  Herbs with Similar Warnings
View List by Warning
  Related Articles
View Articles
  Learn More About
Herbal Medicine

Home | Store Locations | Buy Online | Store Specials | About Us | Delicious Living | Reference Library | News & Features | Health Tools | Treatment Options | Healthy Recipes | Ingredient Glossary | My Account | Contact Us | Help | Shopping Cart | Privacy Policy | Terms of Use |

Powered By Living Naturally