DMDM Hydantoin
Appears in 1 scanned product.
A synthetic preservative that works by slowly releasing small amounts of formaldehyde into a formula to keep microbes from growing.
Why it’s used
Protects water-based products like shampoos and lotions from bacterial and fungal contamination over their shelf life.
What the evidence says
CIR has reviewed it as safe for use in cosmetics at the concentrations typically used. The formaldehyde-releasing mechanism is well understood, and the amounts released are generally far below levels associated with harm in that review. However, individuals with formaldehyde sensitivity can develop contact dermatitis from products containing it, which is a recognized allergen concern rather than a systemic toxicity one.
Context
Relevant mainly for leave-on products where skin contact is prolonged; rinse-off exposure is brief and lower risk. Regulatory limits on total formaldehyde-releaser content exist in some jurisdictions specifically because of the allergy angle, not general toxicity.
Educational information, not medical or safety advice. Consult a professional for allergies or medical concerns.