Preservative
DMDM HYDANTOIN
Safety score · 0–100
Caution
Derived from EU CosIng regulatory status, PubChem hazard data and published research. How we score.
A formaldehyde-releasing preservative — kills microbes by slowly releasing formaldehyde in the product. Effective but a known sensitizer; many brands have phased it out due to allergy concerns.
Function
Skin benefits
- Effective broad-spectrum preservative
- Prevents bacterial and fungal spoilage
- Stable across pH range
Known concerns
- Formaldehyde releaser — releases free formaldehyde in product
- Skin sensitization and allergic contact dermatitis
- Concern for formaldehyde-sensitive consumers
- Increasingly restricted; EU max 0.6% with labeling
References
EU CosIng database
European Commission cosmetic ingredient registry: regulatory status, restrictions, authorised functions.
PubChem
U.S. NIH compound data, GHS hazard codes and toxicity literature.
Frequently Asked Questions
Answers in plain language
Is DMDM hydantoin banned in Europe?
No. DMDM hydantoin is permitted in EU cosmetics as a preservative at a maximum concentration of 0.6%, listed in Annex V of Regulation (EC) 1223/2009. It is a formaldehyde releaser, and products containing it must be labelled "contains formaldehyde" when the released free formaldehyde exceeds 0.05% (500 ppm).
What are the side effects of DMDM hydantoin?
The main concern is contact allergy in people sensitized to formaldehyde, since DMDM hydantoin slowly releases small amounts of formaldehyde to preserve the product. Already-sensitized individuals must avoid all formaldehyde-releasing preservatives. For non-sensitized people at permitted concentrations, no acute side effects are expected.
Related preservatives
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This profile is for educational purposes and does not constitute medical advice. Regulatory status and scientific understanding evolve, so always read the physical product label and consult a healthcare professional for personal concerns.