Ingredient Education · Mar 19, 2026

Formaldehyde and Formaldehyde Releasers

Formaldehyde is a chemical that has been used in a variety of industries, including building materials, textiles, and personal care products. In cosmetics, it is not commonly added directly, but it can still be present through a group of ingredients known as formaldehyde-releasing preservatives.

These preservatives are used to prevent the growth of bacteria, yeast, and mold in water-based products. Instead of adding free formaldehyde, manufacturers may use compounds that slowly release small amounts of formaldehyde over time as part of the preservation system.

This is where the confusion often comes in.

A product may be labeled “formaldehyde-free,” but still contain ingredients that release formaldehyde during use or over the product’s shelf life.

Formaldehyde-releasing preservatives include:

Benzylhemiformal
Bronopol (2-bromo-2-nitropropane-1,3-diol)
Diazolidinyl Urea
DMDM Hydantoin
Glyoxal
Imidazolidinyl Urea
Methenamine
Quaternium-15
Sodium Hydroxymethylglycinate

These ingredients are widely used because they are effective at controlling microbial growth and extending shelf life.

However, effectiveness is only part of the evaluation.

Formaldehyde itself is classified as a known human carcinogen by multiple regulatory and scientific bodies, including the International Agency for Research on Cancer (IARC). This classification is based primarily on inhalation exposure in occupational settings, but it reflects the broader understanding that formaldehyde is not a biologically neutral substance.

Even at lower levels, formaldehyde is a well-documented skin sensitizer and irritant. Repeated exposure can increase the likelihood of developing sensitivity over time, particularly in individuals with compromised or reactive skin.

Formaldehyde-releasing preservatives are designed to release small amounts of formaldehyde gradually. The levels released are considered acceptable within current regulatory limits, and these ingredients are still permitted for use in cosmetics in many regions.

However, “permitted” does not mean without concern.

The release of formaldehyde can vary depending on factors such as formulation, storage conditions, pH, and time. This means the amount of free formaldehyde present in a product may change over its lifespan.

For individuals who are sensitive, even low levels can be enough to trigger reactions.

There is also the broader consideration of cumulative exposure. Formaldehyde and formaldehyde-releasing compounds are not limited to one product category. They can appear across personal care items, household products, and environmental sources. While each individual product may fall within regulatory limits, exposure is rarely isolated to a single source.

For me, this is one of the more straightforward categories to evaluate.

Formaldehyde is a known carcinogen. Formaldehyde-releasing preservatives exist specifically to introduce small amounts of formaldehyde into a product over time. While those amounts are regulated, the mechanism itself is not something I choose to include in formulations, especially when other preservation systems are available.

This is not a situation where the ingredient is essential and difficult to replace.

Because of that, formaldehyde and formaldehyde-releasing preservatives are included on my Ingredients We Avoid list. Since there are effective preservation systems that do not rely on formaldehyde release, this is an easy category to avoid altogether in formulation.

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