Formaldehyde-Releasing Preservatives

What It Is

Formaldehyde-releasing preservatives, sometimes called formaldehyde donors, are a family of compounds that gradually break down in a water-containing product to release small amounts of formaldehyde. Common members include DMDM hydantoin, quaternium-15, imidazolidinyl urea, and diazolidinyl urea. They are used in place of adding formaldehyde directly, because the slow- release mechanism provides ongoing preservation while keeping the free-formaldehyde level low at any given moment.

Common Uses

These preservatives are found in shampoos, conditioners, lotions, liquid soaps, and other water-based personal-care products, as well as in some household products. Their purpose is to prevent contamination by bacteria, yeasts, and molds over the product's shelf life and repeated use. Because they are effective, water-soluble, and low-cost, they were long a common choice for preserving rinse-off and leave-on formulas alike. On a label they appear under their own names rather than as "formaldehyde."

How It Works

Rather than being added as formaldehyde, these ingredients are chemically built so that they release formaldehyde slowly once in a formula, typically in the presence of water. The released formaldehyde disrupts the proteins and enzymes that microorganisms depend on, which stops them from multiplying. Keeping a small, continuous level of formaldehyde present is what gives the family its preservative effect while, in principle, keeping any single measurement of free formaldehyde low.

Safety and Regulation

Formaldehyde itself is classified as a human carcinogen by the International Agency for Research on Cancer and is listed as known to be a human carcinogen by the U.S. National Toxicology Program. Formaldehyde and formaldehyde-releasers are also recognized causes of allergic contact dermatitis in sensitized individuals. In the European Union, formaldehyde is prohibited as an intentionally added cosmetic ingredient, and products containing formaldehyde-releasers must carry a warning label when the released formaldehyde exceeds a set threshold. In the United States, the Food and Drug Administration has addressed formaldehyde in specific product categories such as hair-smoothing treatments. The specifics for each releaser are covered on its own page.

Why Natural Flower Power Does Not Use It

We do not use formaldehyde or any formaldehyde-releasing preservatives in our products. For preservation we use benzisothiazolinone (BIT) at very low levels, which keeps our water-containing formulas stable without this family of ingredients. That has been our approach since we began making our products in-house in 2012. As an independently owned company, we would rather tell you the single preservative we rely on than describe our products only by what they leave out.

Related Ingredients

Members of this family covered in this reference: formaldehyde itself, DMDM hydantoin, quaternium-15, imidazolidinyl urea, and diazolidinyl urea. For broader context on preservatives, see our preservative systems guide and the isothiazolinone preservatives hub, which covers the family we use instead. Related editorial reading: what we put in our products and how we formulate our products. You can also browse our hand soaps, dish soaps, and all-purpose cleaners.

Sources

• International Agency for Research on Cancer (IARC). Monographs, Volume 100F: Formaldehyde (classified as carcinogenic to humans, Group 1).
• U.S. National Toxicology Program. Report on Carcinogens (formaldehyde listed as known to be a human carcinogen).
• European Commission. Regulation (EC) No 1223/2009 on cosmetic products (formaldehyde prohibition and formaldehyde-releaser labeling requirement).
• U.S. Food and Drug Administration. "Formaldehyde in Cosmetics" and hair-smoothing product communications.