Diazolidinyl urea is a water-soluble antimicrobial preservative and formaldehyde releaser that is used in cosmetics as well as in pharmaceuticals. It is produced by the chemical reaction of allantoin and formaldehyde in sodium hydroxide solution and heat. The reaction mixture is then neutralized with hydrochloric acid, which evaporates to leave a solid product called Diazolidinyl Urea.
