Menu

Imidazolidinyl Urea

A formaldehyde-releasing preservative with a separate chemical identity and allergy profile from diazolidinyl urea.

Pen-and-wash drawing of a glass jar and powder spoon
Editorial illustration

Imidazolidinyl urea is a formaldehyde-releasing preservative used in cosmetics and other products. It is not plain moisturizing urea, nor another spelling of diazolidinyl urea. Formaldehyde allergy and allergy to the specific releaser can overlap without being identical, making the exact ingredient relevant to avoidance advice.1, 2

  • A formaldehyde-releasing preservative.1
  • Not interchangeable with plain urea or diazolidinyl urea.2
  • A reaction to a specific releaser can occur without a positive formaldehyde test.1

What is Imidazolidinyl Urea?

This preservative's name resembles both moisturizing urea and another formaldehyde donor. The resemblance should not erase its identity. For a person with contact dermatitis, knowing which substance was implicated is more helpful than avoiding all ingredients with urea in their name or assuming that switching between donors solves the problem.2

Where it comes from

Natural sources

  • Not a source of dietary or skin-moisturizing urea.

How it's made

Manufactured preservative with formaldehyde-donor chemistry.

What it does in products

  • Microbial preservation

Benefits

Preservation of a product

limited evidence

The intended contribution is product preservation, not the moisturizing effect associated with plain urea.1, 2

Clinical allergy and government hazard sources document preservative use and reaction context. They do not establish a standalone therapeutic benefit on skin.

Evidence scope and limitations

Imidazolidinyl urea in preservation and human contact-allergy interpretation; not plain urea moisturizer evidence.

  • No product-specific release measurement or personal reaction probability is provided.
  • Diagnostic concentrations are not consumer use recommendations.

Evidence last checked: 2026-10-01

Side effects & safety

Allergic contact dermatitis (varies)The specific releaser, released formaldehyde or both may be relevant; names alone cannot diagnose the reaction.

Safety considerations

  • Release conditions and exposure are formula-specific. A name on the label does not calculate free-formaldehyde concentration.
  • Not for: Avoid after confirmed relevant imidazolidinyl-urea allergy.
  • Not for: People with formaldehyde sensitization need clinician-guided advice about formaldehyde releasers.
1, 2

Amounts studied & product use

These figures describe research or common product use, not a personal dose or treatment recommendation.

In skincare studies and products

No DIY concentration is supplied. Diagnostic patch-test procedures in allergy literature are not suitable as cosmetic dosing or home-testing instructions.

1

Regulatory status

  • Subject to U.S. cosmetic safety obligations. The cited Australian donor assessment is labeled as hazard context, not an FDA concentration rule.
  • INCI name on cosmetic labels: Imidazolidinyl Urea.
3, 2

Switching between similar preservatives is not a reliable avoidance plan

Sensitivity patterns do not reduce to one ranking of formaldehyde release. A person may need to avoid a specific donor even if their formaldehyde result is negative, or avoid multiple donors if formaldehyde allergy is relevant.

A useful ingredient record therefore retains both the exact name and the clinical reasoning. It should not turn chemical similarity into a promise of cross-tolerance.

1

Frequently asked questions

Is imidazolidinyl urea another name for diazolidinyl urea?

No. They are distinct formaldehyde-releasing preservatives. A test or exposure history for one should not be relabeled as the other.2

Should I avoid plain urea if I react to this preservative?

The shared name fragment does not establish cross-allergy to plain urea. A diagnosis should identify the relevant substance rather than every ingredient containing the word.1, 2

The bottom line

Exact identity matters. Preserve the distinction between plain urea, individual formaldehyde donors and confirmed contact allergy.

References

  1. Goossens A, Aerts O. Contact allergy to and allergic contact dermatitis from formaldehyde and formaldehyde releasers: A clinical review and update. Contact Dermatitis (2022) · other · PMID 35229319; DOI 10.1111/cod.14089
  2. Formaldehyde donors: Human health tier II assessment. Australian Industrial Chemicals Introduction Scheme (2020) · safety assessment
  3. FDA Authority Over Cosmetics: How Cosmetics Are Not FDA-Approved, but Are FDA-Regulated. U.S. Food and Drug Administration (2013) · government guidance · Page updated August 3, 2013; accessed October 1, 2026

Revision history

  1. Initial AI-assisted evidence compilation with source-linked claims, formulation distinctions and explicit research limitations; not independent medical review.