Comfrey salves have been used for centuries to treat skin rashes. Comfrey contains allantoin, a compound that is very effective in healing and soothing the skin. Today allantoin is used in many skin care products, from shampoos to skin creams. Comfrey oil can be diluted with a carrier oil, such as olive, jojoba and coconut oils, and applied to the affected skin. A poultice of comfrey can also be used. Use four cups of freshly picked comfrey leaves. Rinse well, then blend with a quarter cup of a carrier oil. Chill, then spread some onto a clean, soft cloth and wrap around the affected area. Do not apply comfrey to broken skin and open wounds.