Diazolidinyl Urea

Diazolidinyl urea is a widely used antimicrobial preservative in skincare and cosmetic formulations, designed to prevent bacterial, fungal, and mold growth in water-based products. As a formaldehyde-releasing preservative, it slowly releases small amounts of formaldehyde over time to maintain product stability and extend shelf life. It is commonly found in lotions, creams, shampoos, and makeup, ensuring that these products remain safe for use without contamination.

One of diazolidinyl urea’s key advantages is its broad-spectrum antimicrobial activity, making it effective at protecting personal care products from spoilage. It is often combined with other preservatives, such as parabens or iodopropynyl butylcarbamate, to create a more robust preservation system that prevents microbial resistance.

Despite its effectiveness, diazolidinyl urea has been a controversial ingredient due to its association with formaldehyde release. While the amount of formaldehyde it releases is typically within safe limits as regulated by organizations like the FDA and the EU Scientific Committee on Consumer Safety (SCCS), some individuals with sensitive skin or formaldehyde allergies may experience irritation, redness, or contact dermatitis.

Because of these concerns, many skincare brands—especially those focused on clean beauty or sensitive skin formulations—are opting for alternative preservatives such as phenoxyethanol, ethylhexylglycerin, or potassium sorbate. However, diazolidinyl urea remains widely used in conventional formulations due to its high efficacy, low cost, and ability to keep products free from microbial contamination.

For individuals with sensitive or reactive skin, it may be beneficial to check product ingredient lists for diazolidinyl urea and consider preservative-free or naturally preserved alternatives. However, in most cases, when used at regulated concentrations, diazolidinyl urea helps ensure skincare products remain safe, stable, and effective throughout their shelf life.

Diazolidinyl urea (Wikipedia)

Diazolidinyl urea is an antimicrobial preservative used in cosmetics. It is chemically related to imidazolidinyl urea which is used in the same way. Diazolidinyl urea acts as a formaldehyde releaser.

Diazolidinyl urea

newly determined structure
"traditional" structure
Names
IUPAC names 1-[3,4-bis(hydroxymethyl)-2,5-dioxoimidazolidin-4-yl]-1,3-bis(hydroxymethyl)urea (new) 1-[1,3-bis(hydroxymethyl)-2,5-dioxoimidazolidin-4-yl]-1,3-bis(hydroxymethyl)urea (old)
Other names Diazolidinylurea Germall II
Identifiers
CAS Number	78491-02-8 Y
3D model (JSmol)	Interactive image
ChemSpider	56078 Y
ECHA InfoCard	100.071.732
EC Number	278-928-2
PubChem CID	62277
UNII	H5RIZ3MPW4 Y
CompTox Dashboard (EPA)	DTXSID0029559
InChI InChI=1S/C8H14N4O7/c13-1-9-7(18)10(2-14)5-6(17)12(4-16)8(19)11(5)3-15/h5,13-16H,1-4H2,(H,9,18) Y Key: SOROIESOUPGGFO-UHFFFAOYSA-N Y InChI=1/C8H14N4O7/c13-1-9-7(18)10(2-14)5-6(17)12(4-16)8(19)11(5)3-15/h5,13-16H,1-4H2,(H,9,18) Key: SOROIESOUPGGFO-UHFFFAOYAO
SMILES O=C1N(C(=O)C(N(C(=O)NCO)CO)N1CO)CO
Properties
Chemical formula	C8H14N4O7
Molar mass	278.22 g/mol
Hazards
GHS labelling:
Signal word	Warning
Hazard statements	H317
Precautionary statements	P261, P272, P280, P302+P352, P321, P333+P313, P363, P501
NFPA 704 (fire diamond)	1 1 0
Related compounds
Related compounds	Imidazolidinyl urea
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

It 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. Diazolidinyl urea is found in the commercially available preservative Germaben.

Commercial diazolidinyl urea is a mixture of different formaldehyde addition products including polymers.