Comfrey
Introduction
This fact sheet provides basic information about Comfrey. Comfrey grows in moist ground in valleys and meadows in regions from Newfoundland south to Georgia and west to Louisiana. It can also be found in similar climates and geographies in Europe.
Common Names
- Comfrey
- Russian Comfrey
- Knitbone
- Bruisewort
- Blackwort
- Slippery Root
Latin Names
Symphytum officinale
What It Is Used For
Comfrey is most commonly used for the following conditions:
- Bruises
- Sprains and Strains
- Dislocations
- Wounds
How It Is Used
Comfrey’s therapeutic use is limited due to its potential toxicity. It has antifungal and anticancer properties and has been used topically to treat musculoskeletal and inflammatory disorders. However, comfrey is not recommended for oral use due to limited evidence and toxicity concerns.
What the Science Says
- The internal or extensive topical use of comfrey is not recommended because of numerous reports of liver toxicity.
- An extract of S. officinale has been reported to enhance uterine tone, with effects stronger than shepherd’s purse and St. John’s wort, but weaker than those of German chamomile, calendula, and plantain.
- The FDA issued an advisory in July 2001 recommending removing comfrey products from the market following several cases of hepatic veno-occlusive disease. In the same year, the Federal Trade Commission took action against a company marketing comfrey-containing products, leading to a preliminary injunction prohibiting the marketing of such products for internal use or on open wounds, along with a requirement for warnings on external-use products.
Side Effects and Cautions
- Comfrey is not recommended for internal or limited topical use today due to hepatotoxic pyrrolizidine alkaloids (PAs). Older preparations may still be available in Europe and Asia, with historical daily doses of the leaf ranging from 5 to 30 g.
- Due to the hepatotoxic PAs, comfrey is contraindicated for internal use. Individuals with hypersensitivity or allergic reactions to the plant should avoid external use. It is also contraindicated during pregnancy and lactation, as well as in patients with liver or kidney disease.
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