Fresh, peeled root or dried root, approximately 3.5 ounces (100 grams), is simmered in 1 pint (500 ml) of water for ten to fifteen minutes to prepare comfrey for topical use.⁴ Cloth or gauze is soaked in this liquid, then applied to the skin for at least 15 minutes. Fresh leaves can be ground up lightly and applied directly to the skin. Alternatively, creams or ointments made from root or leaf can be applied. All topical preparations should be applied several times per day.

Due to variations in pyrrolizidine alkaloid content, root preparations are unsafe for internal use unless they are guaranteed pyrrolizidine-free. Although comfrey root tea has been used traditionally, the danger of its pyrrolizidine alkaloids is significant. Therefore, comfrey root and young leaf preparations should not be taken internally.