Applying it to broken bones and sprains increases wound healing time considerably.
Comfrey roots and leaves contain allantoin, a substance that helps new skin cells grow, along with other substances that reduce inflammation and keep skin healthy. It is high in Calcium and Vitamin C and simulates healing activity.
The root contains allantoin (a cell proliferant), pyrrolizidine alkaloids (between 10-100 times more than the leaf) such as symphytine, echimidine, helipsupine, viridiflorine, echinatine, amongst others, mucopolysaccharide, carotene, tannins, glycosides, sugars, triterpenoids, rosmarinic acid. It is the pyrrolozadine alakloids component that has the controversy over its internal use.
It can be used as a poultice, or infused oils can be made by making and infused oil, which can then be applied to the skin. If you do not want to make any, contact me. I always have infused comfrey oil around as it is so useful.
Comfrey ointments have been used to heal bruises as well as pulled muscles and ligaments, fractures, sprains, strains, and osteoarthritis.
It is restricted for internal use in Australia.
Fresh comfrey is always best, though dried is better than nothing.