Comfrey: Perennial herb Symphytum officinale, in the family Boraginaceae, used topically for wound healing. It contains ALLANTOIN, carotene, essential oils (OILS, VOLATILE); GLYCOSIDES; mucilage, resin, SAPONINS; TANNINS; triterpenoids, VITAMIN B12, and ZINC. Comfrey also contains PYRROLIZIDINE ALKALOIDS and is hepatotoxic if ingested.Arnica: A plant genus of the family ASTERACEAE. The dried flower heads of Arnica montana are used externally as a counterirritant and tincture for sprains and bruises, either as crude extract or in homeopathic dilution (HOMEOPATHY). Arnica contains volatile oils (OILS, VOLATILE), arnicin, arnisterol, FLAVONOIDS; TANNINS; and resin. The common name of Wolf's Bane is similar to the common name for ACONITUM.Pyrrolizidine Alkaloids: A group of ALKALOIDS, characterized by a nitrogen-containing necine, occurring mainly in plants of the BORAGINACEAE; COMPOSITAE; and LEGUMINOSAE plant families. They can be activated in the liver by hydrolysis of the ester and desaturation of the necine base to reactive electrophilic pyrrolic CYTOTOXINS.Skin Cream: A water-soluble medicinal preparation applied to the skin.Depsides: Phenolic benzoic acid esters.