CAS 6440-58-0 Dimethyloldimethyl Hydantoin (DMDMH) Cosmetic Grade For Shampoos And Conditioners Product Description Description Dimethyloldimethyl Hydantoin (DMDMH) is a broad-spectrum, formaldehyde-releasing liquid preservative and antibacterial agent. Chemically, it is a methylol derivative of 5,5-dimethylhydantoin. It acts as a slow-release reservoir of formaldehyde, providing long-lasting protection against bacteria, yeast, and molds in aqueous systems. Its effectiveness