Truly a botanical powerhouse, comfrey is favored by organic gardeners for its soil-building properties, and beloved by herbalists for its skin-healing powers. If comfrey has an especially potent skin-healing agent, it is allantoin, which researchers have found has soothing, firming and tightening properties.Comfrey accelerates skin-healing, helps keep skin youthful and less susceptible to the formation of wrinkles.