Ingredient guide

Formaldehyde-Releasing Preservatives: The Hidden Allergen Group

Several common preservatives slowly release small amounts of formaldehyde. Here's what they are, why they matter for sensitive skin, and how to spot them.

What they are

Several widely used preservatives work by slowly releasing tiny amounts of formaldehyde, which keeps products free of bacteria. They are known as formaldehyde-releasing preservatives, and they are a single allergen group worth knowing as a set rather than one by one.

Why they matter

Formaldehyde is a recognised contact allergen, and people allergic to it can react to the releasers too. For someone with a known formaldehyde allergy, learning the whole group of release names is the practical way to avoid it, because the word “formaldehyde” rarely appears on the label itself.

Who tends to react

People with eczema or a confirmed formaldehyde allergy are most at risk. As with other preservative allergies, reactions are usually delayed and itchy.

Where they hide

Shampoos, moisturisers, makeup and nail products. The label will not say “formaldehyde”. Instead look for Quaternium-15, DMDM hydantoin, Imidazolidinyl urea, Diazolidinyl urea and Bronopol (2-bromo-2-nitropropane-1,3-diol).

Check products against your list

To check a product, INCIBeauty lets you look up a product and read plain-language notes on each ingredient, with a community that rates them, and a free analyser like Skincarisma lets you paste a product at your desk and see formaldehyde releasers flagged in the ingredient list. These rate a product on general criteria rather than against your own list.

Once you know what you are screening for, a personal-list app like ClearaScan lets you save formaldehyde releasers once and scan any product to flag only your triggers. It also keeps a Reaction Journal for flare-ups, a shared Care Circle so family or carers can scan for you, and a Trusted Products list for items you have cleared, and it is currently in early access. (Disclosure: our editor co-founded ClearaScan, and we are not paid to mention the others.)

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A note on this content. The Sensitive Skin Lab publishes general educational information, not medical advice. If you suspect you have an allergy or sensitivity, consult a qualified dermatologist or allergist. Product formulations and labels change without notice, so always check the ingredients on the product itself.