Imidazolidinyl urea on your skin: a safety profile
Low risk(People-specific data is limited; this page draws from human adult context.) Imidazolidinyl urea (Germall 115; CAS 39236-46-9) is one of the most widely used cosmetic preservatives globally, found in moisturizers, shampoos, hair conditioners, makeup, and baby products. It belongs to the class of formaldehyde-releasing preservatives (FRPs) and achieves its antimicrobial activity by generating free formaldehyde in aqueous formulations through hydrolysis. Imidazolidinyl urea is notable for releasing formaldehyde at higher rates than some other FRPs (such as DMDM hydantoin) under typical cosmetic product conditions (slightly acidic to neutral pH, 20–40°C). The primary regulatory concerns are skin sensitization and cumulative formaldehyde exposure. Imidazolidinyl urea is a recognized contact allergen in its own right, independently of formaldehyde, with patch test positivity rates of 2–5% in patch test clinic populations. It cross-reacts with other formaldehyde releasers and with formaldehyde itself. The EU Cosmetics Regulation (EC No 1223/2009, Annex V, No. 26) permits imidazolidinyl urea at up to 0.6% in rinse-off and leave-on products with mandatory labeling. The SCCS (Scientific Committee on Consumer Safety) reviewed imidazolidinyl urea and found it safe at authorized concentrations for non-sensitized consumers, while flagging the sensitization risk as the key concern. The FDA has received adverse event reports linking FRP-containing cosmetics to dermatitis, scalp reactions, and hair loss, driving regulatory review of the FRP class. Baby and infant products containing imidazolidinyl urea have been a particular focus of consumer advocacy efforts due to concerns about skin barrier immaturity in infants increasing sensitization risk.
What is imidazolidinyl urea?
The IUPAC name is 1-[3-(hydroxymethyl)-2,5-dioxoimidazolidin-4-yl]-3-[[[3-(hydroxymethyl)-2,5-dioxoimidazolidin-4-yl]carbamoylamino]methyl]urea.
Also known as: 1-[3-(hydroxymethyl)-2,5-dioxoimidazolidin-4-yl]-3-[[[3-(hydroxymethyl)-2,5-dioxoimidazolidin-4-yl]carbamoylamino]methyl]urea, IMIDUREA, Germall 115, M629807ATL.
- IUPAC name
- 1-[3-(hydroxymethyl)-2,5-dioxoimidazolidin-4-yl]-3-[[[3-(hydroxymethyl)-2,5-dioxoimidazolidin-4-yl]carbamoylamino]methyl]urea
- CAS number
- 39236-46-9
- Molecular formula
- C11H16N8O8
- Molecular weight
- 388.29 g/mol
- SMILES
- C(NC(=O)NC1C(=O)NC(=O)N1CO)NC(=O)NC2C(=O)NC(=O)N2CO
- PubChem CID
- 38258
Risk for people
Low riskImidazolidinyl urea (Germall 115; CAS 39236-46-9) is one of the most widely used cosmetic preservatives globally, found in moisturizers, shampoos, hair conditioners, makeup, and baby products. It belongs to the class of formaldehyde-releasing preservatives (FRPs) and achieves its antimicrobial activity by generating free formaldehyde in aqueous formulations through hydrolysis. Imidazolidinyl urea is notable for releasing formaldehyde at higher rates than some other FRPs (such as DMDM hydantoin) under typical cosmetic product conditions (slightly acidic to neutral pH, 20–40°C). The primary regulatory concerns are skin sensitization and cumulative formaldehyde exposure. Imidazolidinyl urea is a recognized contact allergen in its own right, independently of formaldehyde, with patch test positivity rates of 2–5% in patch test clinic populations. It cross-reacts with other formaldehyde releasers and with formaldehyde itself. The EU Cosmetics Regulation (EC No 1223/2009, Annex V, No. 26) permits imidazolidinyl urea at up to 0.6% in rinse-off and leave-on products with mandatory labeling. The SCCS (Scientific Committee on Consumer Safety) reviewed imidazolidinyl urea and found it safe at authorized concentrations for non-sensitized consumers, while flagging the sensitization risk as the key concern. The FDA has received adverse event reports linking FRP-containing cosmetics to dermatitis, scalp reactions, and hair loss, driving regulatory review of the FRP class. Baby and infant products containing imidazolidinyl urea have been a particular focus of consumer advocacy efforts due to concerns about skin barrier immaturity in infants increasing sensitization risk.
Regulatory consensus
10 regulatory and scientific bodies have classified Imidazolidinyl urea. The classifications differ — that's the data.
| Agency | Year | Classification | Notes |
|---|---|---|---|
| US EPA | 2000 | not classifiable as to human carcinogenicity (Group D) | |
| EFSA | 2014 | not evaluated for carcinogenicity; contact sensitizer and formaldehyde releaser regulated under EU Cosmetics Regulation (EC) No 1223/2009 Annex V; maximum authorized concentration 0.6% in cosmetics; mandatory labeling above 0.05% free formaldehyde; SCCS opinion 2014 confirmed safety at current use levels for non-sensitized consumers | |
| EPA CTX / Genetox | — | Genotoxicity: positive (Ames: positive, 1 positive / 5 negative reports) | |
| EPA CTX / Genetox | — | Genotoxicity: positive (Ames: positive, 1 positive / 5 negative reports) | |
| EPA CTX / Skin-Eye | — | Skin Sensitization: SkinSens1 (score: high) | |
| EPA CTX / Skin-Eye | — | Eye Irritation: Category 6.4A (Category 2A) (score: high) | |
| EPA CTX / Skin-Eye | — | skin sensitisation: in vivo (LLNA): High Frequency of Sensitization (score: high) | |
| EPA CTX / Skin-Eye | — | skin sensitisation: in vivo (non-LLNA): High Frequency of Sensitization (score: high) | |
| EPA CTX / Skin-Eye | — | eye irritation: in vivo: Studies Indicate No Significant Irritation (score: low) | |
| EPA CTX / Skin-Eye | — | skin irritation: in vivo: Studies Indicate No Significant Irritation (score: low) |
Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.
Where you encounter imidazolidinyl urea
- Industrial Facilities — Manufacturing plants, Chemical storage areas, Waste treatment sites
- Occupational Environments — Factories, Warehouses, Transportation vehicles
- Personal Care — shampoo, conditioner, lotion, cosmetics, sunscreen
Safer alternatives
Lower-risk approaches that achieve a similar outcome to Imidazolidinyl urea:
-
Phenoxyethanol
Trade-offs: Alternative preservation system; spectrum of antimicrobial activity differs (gram+/gram-, yeasts, molds); pH range of efficacy varies; challenge testing per ISO 11930 required for cosmetics.Relative cost: 1.2-2×
-
Ethylhexylglycerin
Trade-offs: Alternative preservation system; spectrum of antimicrobial activity differs (gram+/gram-, yeasts, molds); pH range of efficacy varies; challenge testing per ISO 11930 required for cosmetics.Relative cost: 1.2-2×
-
Caprylyl glycol
Trade-offs: Alternative preservation system; spectrum of antimicrobial activity differs (gram+/gram-, yeasts, molds); pH range of efficacy varies; challenge testing per ISO 11930 required for cosmetics.Relative cost: 1.2-2×
Frequently asked questions
What products contain imidazolidinyl urea?
Imidazolidinyl urea appears in: Manufacturing plants (Industrial facilities); Chemical storage areas (Industrial facilities); Factories (Occupational environments); Warehouses (Occupational environments); shampoo (Personal care).
Why do regulators disagree about imidazolidinyl urea?
Imidazolidinyl urea has been classified by 10 agencies including US EPA, EFSA, EPA CTX / Genetox, EPA CTX / Genetox, EPA CTX / Skin-Eye, with differing conclusions. Regulators apply different standards of evidence (animal data weighting, exposure-pattern assumptions, epidemiological power thresholds), which is why two scientific bodies can review the same data and reach different conclusions. See the regulatory consensus table on this page for the full picture.
See Imidazolidinyl urea in the body app
Look up products containing imidazolidinyl urea, compare to alternatives, and explore the full data record.
Open in body View raw API dataSources (2)
- US EPA Imidazolidinyl Urea: Group D Not Classifiable; Formaldehyde-Releasing Preservative Germall 115; Contact Sensitizer; Patch Test Positivity 2–5%; Cumulative Formaldehyde Exposure Assessment; FDA Adverse Event Reports (2000) — regulatory
- EFSA/SCCS Imidazolidinyl Urea: EU Cosmetics Regulation Annex V No. 26; Maximum 0.6% Permitted; Mandatory Formaldehyde Labeling; Infant Skin Barrier Concern; Eczema Risk Factor; Baby Product Reformulation Trend (2014) — regulatory
Reference data, not professional advice. Aggregates publicly available regulatory and scientific data; not a substitute for veterinary, medical, legal, or regulatory advice. Why we built ALETHEIA →