Diazolidinylurea is a broad-spectrum antimicrobial preservative used in cosmetics and pharmaceutical preparations. It is especially active against gram-negative bacteria and is often combined with parabens. Diazolidinylurea is the most active member of the imidazolidinyl urea group, that acts as a formaldehyde releasers. Diazolidinylurea is used in many cosmetics, skin care products, shampoos, and conditioners, as well as a wide range of products including bubble baths, baby wipes, and household detergents.