Allantoin

Allantoin (CAS #97-59-6) is a chemical compound (Urea, (2,5-Dioxo-4-Imidazolidinyl)-) that occurs naturally in the roots and leaves of the comfrey plant, though the form used in cosmetic products is most commonly produced synthetically. Its official CosIng functions are listed as skin conditioning, skin protecting, and soothing. It is considered a super common cosmetic ingredient and carries an irritancy rating of 0.