Imidazolidinyl Urea: Properties and Cosmetic Applications

What Is Imidazolidinyl Urea?

Imidazolidinyl Urea is primarily an antibacterial preservative with very limited antifungal activity. It has been widely used in cosmetic products since its introduction in the 1980s.

It is highly water-soluble and should be added to cosmetic formulations at temperatures below 40°C to minimise decomposition. It remains active across a relatively broad pH range of approximately pH 3–9.

Key Properties of Imidazolidinyl Urea

Antibacterial Activity
Imidazolidinyl Urea is primarily effective against bacteria, while its antifungal activity is limited.

Water Solubility
Its high water solubility makes it particularly suitable for aqueous cosmetic formulations.

Broad pH Stability
It retains preservative activity across a pH range of approximately 3–9.

Heat Sensitivity
The ingredient should be incorporated below 40°C to avoid decomposition.

Cosmetic Applications

Imidazolidinyl Urea can be used as a preservative in a variety of cosmetic formulations. Typical use concentrations are approximately 0.2–0.5%, depending on the formulation and applicable regulatory requirements.

Formulation Considerations

One consideration associated with Imidazolidinyl Urea is its potential to release very low levels of formaldehyde. This characteristic is considered a disadvantage by some formulators and consumers.

Its use is subject to regulatory restrictions in different markets, so the applicable requirements should always be checked for the intended product and market.

Ingredient Information

INCI: Imidazolidinyl Urea
CAS: 39236-46-9
EINECS/EC: 254-372-6

References

Cosmetic Formulation Principles and Practice – Heather A.E. Benson, Michael S. Roberts, Vânia Rodrigues Leite-Silva, Kenneth A. Walters.