A poultice of the crushed leaves accelerates healing of surface wounds and sores and broken bones. Comfrey contains a substance called allantoin used in ointments for psoriasis and other skin problems. Comfrey tea, said to ease bronchial and intestinal disorders, may not be safe when taken over a long period of time.
Do not confuse the plant when not in bloom with foxglove, a deadly poisonous plant. There is evidence that comfrey may cause cancer if taken internally over a long period of time.