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DMDM Hydantoin

What DMDM Hydantoin is & what it does

A preservative that works by slowly releasing small amounts of formaldehyde to keep formulas microbe-free. It is effective but can be sensitizing for those reactive to formaldehyde.

What is DMDM Hydantoin and what does it do in sunscreen?

DMDM Hydantoin is a preservative that keeps a water-containing formula free of bacteria, mould and yeast over its shelf life. It works as a formaldehyde releaser, meaning it protects the product by slowly giving off very small amounts of formaldehyde. In a sunscreen its only job is to keep the formula stable and safe to use.

Is DMDM Hydantoin safe?

It is permitted and considered safe at the low levels used in cosmetics, but it is more likely to cause issues than gentler preservatives. Because it releases trace formaldehyde, people who are sensitive or allergic to formaldehyde can react to it, and some prefer to avoid formaldehyde releasers altogether. For most people without that sensitivity it does its preserving job uneventfully.

Does DMDM Hydantoin clog pores?

No. It is a water-soluble preservative used in very small amounts, not an oil or wax, so it is not a pore-clogging ingredient. If a sunscreen is breaking you out, the heavier emollients in the formula are far more likely the cause than the preservative.

Is DMDM Hydantoin a formaldehyde releaser?

Yes. DMDM Hydantoin preserves a product by slowly releasing tiny amounts of formaldehyde, which is what keeps microbes from growing. This is why people with a formaldehyde sensitivity are advised to avoid it, even though the released amounts are very small. It is one of several formaldehyde-releasing preservatives used in cosmetics.

Is DMDM Hydantoin a preservative?

Yes. Its sole role in a formula is preservation, stopping bacteria, mould and yeast from spoiling a water-based product. It is sometimes mistaken for an active because of its chemical name, but it adds no skincare benefit beyond keeping the product safe. You will usually find it near the other preservatives on the ingredient list.

What is DMDM Hydantoin on an ingredient list (INCI)?

On the label it appears as its INCI name, DMDM Hydantoin. It typically sits near the end of the ingredient list, where preservatives are usually found because they are used in small amounts. Seeing it there simply means the product has a preservative system to keep it microbe-free.

Sunscreens with DMDM Hydantoin

We rate 101 sunscreens that contain it, showing the top 10 by overall score:

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