It grows up to four feet tall in some regions and contains purple-white flowers arranged in dense clusters. Its root is slimy and has a horn-like appearance, with a black exterior and a fleshy white interior. Comfrey has traditionally been used to treat superficial wounds, as well as the inflammation that accompanies sprains and broken bones. Recent studies conducted in animals show that comfrey has healing and pain-relieving properties and stimulates the actions of certain liver enzymes. Other studies suggest that comfrey may be useful in treating gastrointestinal disorders and peptic ulcers.
Pyrrolizidine alkaloids are poisonous compounds that can cause severe liver damage.
You should use only products that are made from the leaves of common comfrey. While some people think comfrey is a beneficial herb, studies have shown that it can be quite toxic. Other comfrey species have dangerously high levels of a compound called echimidine. When taking comfrey, always make sure to use reputable commercial brands that employ good quality manufacturing practices. Use only the amount recommended on the label.