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Imidazolidinyl Urea in skincare
Formaldehyde-releasing preservative; stronger releaser than DMDM hydantoin; known human allergen.
Used as a preservative in both AM and PM products. PM leave-on formulations carry higher sensitization risk than rinse-off products due to prolonged formaldehyde contact. Best replaced by phenoxyethanol/ethylhexylglycerin/caprylyl glycol systems. Cumulative daily FRP exposure is the sensitization driver. Reduce across all products.
What it is
Imidazolidinyl Urea (Germall 115) is a formaldehyde-releasing preservative (FRP) that releases formaldehyde to inhibit microbial growth. Like DMDM hydantoin but considered a more potent formaldehyde releaser. FDA lists it as a known cosmetic allergen. The American Contact Dermatitis Society identifies it as among the most common FRP allergens. IARC considers formaldehyde a Group 1 carcinogen (from inhalation exposure). EU permits up to 0.6% in finished products; tightening warning label requirements (>0.001% triggers label warning, proposed 2024). Banned in California, Maryland, Oregon, Washington State, and Vermont as an FRP. Dermatologists and clean-beauty formulations uniformly recommend replacement with non-FRP preservative systems. Best avoided, particularly in leave-on facial products.
The facts
| Category | Preservative (Formaldehyde Releaser) |
| Typical use | Morning and evening |
| Concentration YARAI treats as a full dose | 0.6% |
| EU maximum permitted concentration | 0.6% (0.6%) |
| EU Cosmetics Regulation annex | V |
| EU status | restricted |
| EU and US differ | FDA has no specific limit on formaldehyde releasers in cosmetics. |
Why the amount matters, not just the presence
Most ingredient checkers tell you whether something is in the bottle. That is a smaller question than it sounds. Imidazolidinyl Urea at 0.6% and imidazolidinyl urea at a trace level are not the same ingredient in any way that affects your skin.
An ingredient list is ordered by quantity, so position carries real information. YARAI reads that position and scores accordingly, which is why the same ingredient can land differently in two different products.
The honest limit: a list gives order, not percentages. Estimating concentration from position is an estimate. It is a better estimate than ignoring position, and it is still an estimate. We would rather tell you that than let a number look more certain than it is.
Regulatory status
EU Annex V preservative, max 0.6%. Formaldehyde releaser: since Reg. 2022/1181, any product releasing over 0.001% must carry the releases-formaldehyde warning.
Common questions
What does imidazolidinyl urea do in a skincare product?
Formaldehyde-releasing preservative; stronger releaser than DMDM hydantoin; known human allergen.
How much imidazolidinyl urea should a product contain?
YARAI treats 0.6% as a full dose for this ingredient. Below that, the ingredient is present but is scored as contributing less. An ingredient list gives you the order of ingredients, not their percentages, so this is an estimate read from position rather than a measurement.
Is imidazolidinyl urea restricted in the EU?
The EU Cosmetics Regulation permits this ingredient up to 0.6% in leave-on cosmetics, listed under V. 0.6%
When should I use imidazolidinyl urea?
Used as a preservative in both AM and PM products. PM leave-on formulations carry higher sensitization risk than rinse-off products due to prolonged formaldehyde contact. Best replaced by phenoxyethanol/ethylhexylglycerin/caprylyl glycol systems. Cumulative daily FRP exposure is the sensitization driver. Reduce across all products.
Check your own products
Point your camera at a product. YARAI identifies it from the label, finds that product's full ingredient list from published sources, and scores it. No barcode and no box needed, which is how it handles imported and small-brand products.
Concern level, category and thresholds on this page are read directly from the same data the YARAI app scores with, so this page and the app cannot disagree. EU figures cite Regulation (EC) No 1223/2009. Last built 2026-09-09. Nothing here is medical advice.