Allantoin is the healing compound found within the comfrey plant. Allantoin is also found in the milk of nursing mothers and in the fetal allantois, a tube-like sac that eventually becomes part of the placenta.

Allantoin in some way affects the multiplication of cells and tissue growth. Pharmaceutically added to creams and ointments, it is believed to help foster the healing process of wounds, burns, and skin problems.