7 Formaldehyde-Releasing Preservatives to Know About — and Why En Care Of Chooses a Different Approach

When you turn over a bottle of lotion, shampoo, cleanser, or another personal-care product, you probably won’t see the word “formaldehyde” printed on the ingredient list.

But that doesn’t necessarily mean a formula can’t release small amounts of formaldehyde.

Some preservatives used in cosmetics are known as formaldehyde-releasing preservatives, sometimes called formaldehyde donors. They help protect water-containing products from bacteria, yeast, and mold by gradually releasing small amounts of formaldehyde into the formulation.

Preservation is important. An improperly preserved water-based cosmetic can become contaminated and potentially unsafe.

At En Care Of, however, we believe preservation should also be purposeful, transparent, and appropriate for the formulation.

That starts with understanding what our ingredients actually do.

What Are Formaldehyde-Releasing Preservatives?

Formaldehyde-releasing preservatives are ingredients designed to release small amounts of formaldehyde over time to help control microbial growth.

According to the U.S. Food and Drug Administration (FDA), formaldehyde and formaldehyde-releasing ingredients are among substances consumers may encounter when evaluating potential allergens in cosmetics.

For individuals who are sensitized to formaldehyde, exposure to formaldehyde or certain formaldehyde-releasing preservatives can contribute to allergic contact dermatitis.

That’s why we believe consumers deserve to know what these ingredients are called—not just what they do.

7 Formaldehyde-Releasing Preservatives Worth Recognizing

1. DMDM Hydantoin

DMDM Hydantoin is a preservative that may be used in shampoos, conditioners, lotions, and other personal-care products.

Its preservation mechanism involves releasing small quantities of formaldehyde over time to help control microorganisms.

For individuals with a formaldehyde allergy or sensitivity, formaldehyde-releasing preservatives may be a potential source of skin irritation or allergic contact dermatitis.

2. Diazolidinyl Urea

Diazolidinyl Urea is another antimicrobial preservative used to help extend the usable life of cosmetic formulations.

Despite having “urea” in its name, it shouldn’t be confused with the moisturizing urea commonly used in skincare.

Diazolidinyl Urea is classified as a formaldehyde-releasing preservative.

3. Imidazolidinyl Urea

Imidazolidinyl Urea is used to help prevent microbial contamination and maintain product stability.

Like Diazolidinyl Urea, it can release formaldehyde as part of its preservation mechanism.

For people who carefully select products because of sensitive or reactive skin, recognizing these ingredient names can make cosmetic labels much easier to understand.

4. Quaternium-15

Quaternium-15 is another recognized formaldehyde-releasing preservative.

It has been associated with allergic contact dermatitis, particularly among individuals who are already sensitized to formaldehyde.

This illustrates an important part of the En Care Of philosophy:

An ingredient can perform its intended function while still not being the ingredient choice we want for our formulations.

5. Bronopol

You may see this ingredient listed as:

2-Bromo-2-Nitropropane-1,3-Diol

Bronopol is an antimicrobial preservative capable of releasing formaldehyde.

Its complicated chemical name also demonstrates why cosmetic ingredient education is so important. Consumers can’t make informed decisions about ingredients they’ve never been taught to recognize.

6. Sodium Hydroxymethylglycinate

Sodium Hydroxymethylglycinate is also recognized by the FDA among formaldehyde-releasing cosmetic ingredients.

This ingredient is a good reminder that terms such as “natural” or “naturally derived” don’t tell the entire story about how an ingredient functions within a finished cosmetic.

At En Care Of, we prefer to look at what an ingredient does, not simply the marketing category surrounding it.

7. 5-Bromo-5-Nitro-1,3-Dioxane

This is another formaldehyde-releasing ingredient identified by the FDA.

It’s considerably less recognizable to the average consumer than ingredients such as parabens or sulfates—which makes ingredient education even more valuable.

The European Union Requires a Formaldehyde Warning in Certain Cosmetics

One of the most interesting developments surrounding formaldehyde-releasing cosmetic ingredients comes from the European Union.

Under EU Regulation (EU) 2022/1181, finished cosmetic products containing substances covered by the regulation that release formaldehyde must carry the warning:

“releases formaldehyde”

when the total concentration of formaldehyde released in the finished product exceeds 0.001% — equivalent to 10 parts per million (ppm).

The requirement applies regardless of whether the finished product contains one or multiple formaldehyde-releasing substances.

This is an important distinction.

The regulation does not mean that every cosmetic containing a formaldehyde-releasing preservative is automatically considered dangerous.

Instead, the labeling requirement gives consumers additional information about formaldehyde exposure from the finished product—including consumers who may already be sensitized to formaldehyde.

For En Care Of, this type of transparency reflects something we strongly believe:

Consumers deserve to understand what’s in the products they use.

Does This Mean All Preservatives Are Bad?

Absolutely not.

This may be the most important point in this entire conversation.

Preservatives serve an essential safety function in many cosmetics.

Products containing significant amounts of water can provide an environment where bacteria, yeast, and mold can grow. An inadequately preserved product can therefore present its own safety risks.

At En Care Of, our philosophy isn’t:

“Preservatives are bad.”

It’s:

“Preservation should be appropriate, purposeful, and transparent.”

We also don’t believe in labeling every cosmetic containing a formaldehyde-releasing preservative as “toxic” or “dangerous.”

Cosmetic safety depends on multiple factors, including formulation, concentration, exposure, regulatory limits, and individual sensitivity.

Our goal is to help consumers understand their options.

Why En Care Of Takes a Different Approach

En Care Of was built around thoughtfully formulated, small-batch hair and skincare.

Rather than asking:

“What can we add to make this product last as long as possible?”

we prefer to ask:

“What does this formula actually need?”

That distinction matters.

Many En Care Of products are anhydrous, meaning they’re formulated without significant amounts of water.

Products such as body butters, beard oils, hair oils, and body oils generally don’t require the same type of broad-spectrum preservation system as a traditional water-based lotion or cream when they are properly formulated, manufactured, packaged, and used.

This gives us the opportunity to build many of our formulas around carefully selected oils, butters, and functional cosmetic ingredients.

Depending on the specific En Care Of formulation, those may include ingredients such as:

Shea Butter • Mango Butter • Murumuru Butter • Jojoba Oil • Argan Oil • Grapeseed Oil • Sunflower Oil • Rosehip Oil • Vitamin E • Colloidal Oatmeal • Bisabolol

Each ingredient should have a reason for being there.

Small-Batch Isn’t Just a Marketing Phrase

En Care Of products are handcrafted in small batches, with many products made to order.

For us, small-batch production means being intentional about:

Ingredient selection
Freshness
Batch size
Formulation decisions
Product consistency

It also allows us to continually learn about cosmetic ingredients and make formulation decisions based on what makes sense for the individual product.

Sensitive Skin Deserves Thoughtful Formulation

Anyone with sensitive or reactive skin knows that a longer ingredient list doesn’t necessarily mean a better product.

Sometimes thoughtful formulation means knowing what not to add.

That’s why En Care Of focuses on combining nourishing butters, botanical oils, and carefully selected functional ingredients without unnecessarily complicating a formulation.

And there’s an important distinction we want our customers to understand:

We don’t believe in fear-based beauty.

We believe in ingredient-conscious beauty.

You shouldn’t have to be afraid of an ingredient simply because its name sounds chemical.

But you should have access to enough information to understand what that ingredient does.

Become an Ingredient-Label Reader

If avoiding formaldehyde-releasing preservatives is important to you, familiarize yourself with these names:

DMDM Hydantoin
Diazolidinyl Urea
Imidazolidinyl Urea
Quaternium-15
Bronopol / 2-Bromo-2-Nitropropane-1,3-Diol
Sodium Hydroxymethylglycinate
5-Bromo-5-Nitro-1,3-Dioxane

You don’t need a chemistry degree to become more informed about the products you put on your skin and hair.

Sometimes it starts with simply turning the bottle around and reading.

The En Care Of Difference

At En Care Of, we believe skincare should be:

Intentional.
Transparent.
Thoughtfully formulated.

Our small-batch products are created with carefully selected ingredients and a focus on creating enjoyable, nourishing hair and skincare experiences.

We aren’t interested in making an ingredient sound frightening just to sell you an alternative.

We’re interested in helping you understand why we formulate the way we do.

Because what we choose to leave out can be just as intentional as what we choose to put in.

En Care Of — small-batch care, thoughtfully formulated.

Sources & Further Reading

U.S. Food & Drug Administration (FDA) — Allergens in Cosmetics
The FDA identifies formaldehyde and formaldehyde-releasing ingredients that may appear in cosmetics, including Bronopol, 5-Bromo-5-Nitro-1,3-Dioxane, Diazolidinyl Urea, DMDM Hydantoin, Imidazolidinyl Urea, Sodium Hydroxymethylglycinate, and Quaternium-15.

European Commission / EUR-Lex — Commission Regulation (EU) 2022/1181
This regulation amended EU cosmetic labeling requirements for formaldehyde-releasing substances. Finished products covered by the regulation must carry the warning “releases formaldehyde” when the total concentration of released formaldehyde exceeds 0.001% (10 ppm).

Goossens A, Aerts O. Contact allergy to and allergic contact dermatitis from formaldehyde and formaldehyde releasers: A clinical review and update. Contact Dermatitis. 2022;87(1):20–27.
A peer-reviewed clinical review discussing formaldehyde and major formaldehyde-releasing preservatives in relation to contact allergy and allergic contact dermatitis.

Important Cosmetic & Health Disclaimer

This article is provided by En Care Of for general cosmetic ingredient education only and is not intended to provide medical advice, diagnose or treat a medical condition, or suggest that a cosmetic ingredient is unsafe under all conditions of use.

The presence of a formaldehyde-releasing preservative does not automatically mean that a cosmetic product is unsafe. Ingredient safety depends on factors including concentration, finished formulation, exposure, regulatory requirements, and individual sensitivity.

The European Union labeling information discussed above refers specifically to EU cosmetic regulations and should not be interpreted as a U.S. labeling requirement. Under EU Regulation (EU) 2022/1181, covered finished cosmetic products that release formaldehyde above 0.001% (10 ppm) must carry the warning “releases formaldehyde.”

Individuals with known allergies, contact dermatitis, highly reactive skin, or other skin conditions should consult a dermatologist or qualified healthcare professional regarding ingredients that may be appropriate for them.

Product formulations and ingredient lists may vary. Always refer to the ingredient list provided with the individual En Care Of product for the most accurate information.