Comfrey

Common names: Comfrey also is known as Russian comfrey, knitbone, bruisewort , blackwort, and slippery root.

Efficacy-safety rating:

ÒÒ...Ethno or other evidence of efficacy.

Safety rating:

What is Comfrey?

Comfrey is a perennial plant found in moist grasslands. It has bell-shaped purple or yellow-white flowers. Comfrey usually is associated with temperate regions of the world, including western Asia, North America, and Australia.

What is Comfrey used for?

Comfrey has been cultivated in Japan as a green vegetable and has been used as an herbal medicine for over 2,000 years.

Comfrey's original name, knitbone, derives from the external use of poultices of its leaves and roots to heal burns, sprains, swelling, and bruises. Comfrey has been used topically for treating inflammatory disorders such as arthritis, thrombophlebitis, and gout. It has been used internally to treat GI disorders (eg, diarrhea, gastric ulcers, hemorrhoids), bronchial congestion, and inflammation. Comfrey distribution is banned in Germany and Canada because of the substantial health hazard and toxicity of the plant. The sale of comfrey products for internal use also is banned in the United States.

What is the dosage of Comfrey?

Comfrey is not recommended for internal or even limited topical use today because of the content of hepatotoxic (toxic to the liver) pyrrolizidine alkaloids (PAs). Older preparations still may be on the market in Europe and Asia. For informational purposes, typical older daily doses of the leaf ranged from 5 to 30 g.

Is Comfrey safe?

Because of the content of hepatotoxic pyrrolizidine alkaloids, comfrey is not recommended for internal use.

Documented adverse effects (pyrrolizidine alkaloids, risk of fatal hepatic veno-occlusive disease [VOD], abortive effects). Avoid use.

None well documented.

The internal or extensive topical use of comfrey cannot be recommended because of numerous reports of liver toxicity.

Evidence indicates that comfrey is unsafe in any form.

References

Copyright © 2006 Wolters Kluwer Health

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