Ingredient Index

Is DMDM Hydantoin banned in Europe?

Restricted in EU

No: DMDM hydantoin is legal in the EU as a preservative up to 0.6%, with a mandatory "releases formaldehyde" label above the release threshold; the US permits it with no concentration limit.

CAS: 6440-58-0 Also seen as: 1,3-Dimethylol-5,5-dimethylhydantoin

What the EU does

Permitted with a leash. DMDM hydantoin is an authorized preservative under Annex V of Regulation (EC) No 1223/2009, capped at 0.6%. Because it works by releasing small amounts of formaldehyde, it is also caught by the EU's release-labeling rule: since 2022, any product releasing more than 10 ppm free formaldehyde must state "releases formaldehyde" on the pack.

That labeling rule, tightened by Commission Regulation (EU) 2022/1181, exists for the roughly 2–3% of people sensitized to formaldehyde, for whom these products are a genuine dermatitis trigger.

Citation Regulation (EC) No 1223/2009, Annex V/33 (max 0.6%); Commission Regulation (EU) 2022/1181

What the US does

Legal with no federal concentration limit; the industry's CIR panel considers it safe as used. It remains one of the most common preservatives in US haircare.

The US story is in the courtroom rather than the rulebook: class actions against major shampoo lines (OGX and others) alleged DMDM hydantoin contributed to hair loss and scalp irritation, and several brands reformulated or settled without admitting the science. No FDA action has followed (hair-loss causation was never established), but the ingredient's US footprint is shrinking for reputational reasons.

Citation FD&C Act general safety standard; CIR safety assessment of DMDM hydantoin

Products that commonly contain it

A water-phase preservative, most at home in rinse-off products:

Shampoos and conditioners
Body washes and liquid soaps
Lotions and facial cleansers
Styling gels

What to look for on a label

What to scan for:

"DMDM hydantoin" in the ingredient list, usually mid-list
"Releases formaldehyde" wording on EU-market products
Sensitized to formaldehyde? Also avoid diazolidinyl urea, imidazolidinyl urea, and quaternium-15

Or skip the squinting: paste the whole ingredient list into our checker and it flags everything in our database. Nothing you paste leaves your browser.

Frequently asked questions

Is DMDM hydantoin banned in Europe?

No. It is authorized under Annex V of the Cosmetics Regulation at up to 0.6%, with a mandatory "releases formaldehyde" label when free formaldehyde exceeds 10 ppm.

Is DMDM hydantoin legal in the United States?

Yes, with no concentration limit. Several major brands have nonetheless reformulated away from it after class-action lawsuits over alleged hair loss.

Does DMDM hydantoin cause hair loss?

It has never been established. The lawsuits settled or proceeded on consumer-protection grounds rather than proven causation. The documented risk is contact dermatitis in people sensitized to formaldehyde.

Why use a formaldehyde releaser at all?

Slow, low-level formaldehyde release is a very effective way to keep water-based products free of bacteria and mold. The EU's judgment is that under 0.6%, with labeling for the sensitized, the trade-off is acceptable.

Related ingredients

Primary sources

Last reviewed June 10, 2026 · How we assign statuses