Diazolidinyl Urea



No known benefits

Diazolidinyl Urea description

Diazolidinyl urea is a water-soluble preservative. This preservative is considered safe for use at concentrations up to 0.5%, although it’s usually present at lower concentrations because it’s typically part of a blend with other preservatives (such as parabens). Diazolidinyl urea can be a formaldehyde-releasing preservative. Although that sounds scary, the amount of formaldehyde released is well below the recommended limits of exposure. Moreover, other ingredients (such as proteins) in a product cause the free formaldehyde to evaporate and become inactive before it could possibly harm skin. See formaldehyde-releasing preservative

Diazolidinyl Urea references

  • Steinberg, David C., Preservatives for Cosmetics, Third Edition, Allured Books, 2012, pages 67-68
  • Contact Dermatitis, August 2011, pages 81-91; and January 2006, pages 50-58
  • International Journal of Toxicology, March-April 1990, issue 2, pages 229-245

Peer-reviewed, substantiated scientific research is used to assess ingredients in this dictionary. Regulations regarding constraints, permitted concentration levels and availability vary by country and region.

Ingredient ratings


Proven and supported by independent studies. Outstanding active ingredient for most skin types or concerns.


Necessary to improve a formula's texture, stability, or penetration.


Generally non-irritating but may have aesthetic, stability, or other issues that limit its usefulness.


There is a likelihood of irritation. Risk increases when combined with other problematic ingredients.


May cause irritation, inflammation, dryness, etc. May offer benefit in some capability but overall, proven to do more harm than good.


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Not rated