(Symphytum officinale)  Common names: Knitbone, boneset. 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. 

Comfrey has a long, consistent history of use as a topical agent for improving healing of wounds, skin ulcers, thrombophlebitis, strains, and sprains. Also of note is the use of comfrey to promote more rapid repair of broken bones. Comfrey has a reputation as an anti-inflammatory for a variety of rashes. It was also used for persons with gastrointestinal problems, such as stomach ulcers and inflammatory bowel disease, and for lung problems.

The major compounds found in comfrey that promote healing are mucilage and allantoin.

Fresh, peeled root (approximately 100 grams) or dried root is simmered in 1 pint (250 ml) water for ten to fifteen minutes to prepare comfrey for topical use. Cloth or gauze is soaked in this liquid, then applied to the skin for at least fifteen minutes.  Fresh leaves can be ground up lightly and applied directly to the skin. Creams or ointments made from root or leaf can be applied. All topical preparations should be applied several times per day. To aid the healing of a broken bone, a window would need to be left in the cast near the fracture site, and comfrey applied. However, this is not always possible.

Note:  Root preparations are unsafe for internal use unless they are guaranteed pyrrolizidine-free. Tea made from the leaf can generally be used safely for as long as a month. Tea is made by steeping 1–2 teaspoons of leaf in hot water for fifteen minutes. Three cups per day can be drunk.  2–4 ml of tincture taken three times per day for no more than one month consecutively. Tinctures that are guaranteed pyrrolizidine-free are preferable and can be taken long-term.