Formaldehyde: A Safe Preservative?

A common preservative in skin care products

Credits: Efraimstochter at
Edited By:
Raja Sivamani , MD, MS, AP

If you have ever dissected something for a biology class, then you are familiar with formaldehyde’s pungent scent and its use as a preservative. Found in nearly one-fifth of all cosmetics, formaldehyde and its related ingredients are some of the most commonly used preservatives due to its antimicrobial properties; it can additionally be used as a denaturant to break apart proteins.[1] Widely used for embalming in funerary practices, formaldehyde works by causing proteins to bind in such a way that they become stiff, impeding the decomposition process.[2] This property of formaldehyde is also how nail hardeners work and why it is such a practical preservative in cosmetics: it will affect the bacteria and fungi proteins, killing them.[3] Formaldehyde is a natural product found in fruits and even our own bodies, where it is metabolized into carbon dioxide.[4] But is this effective ingredient safe in the products we use on our skin?

Formaldehyde has been known to cause contact dermatitis with sensitization (a type of eczema due to an allergic response) in the United States, affecting up to 9% of the population.[5] However, like many allergies, this is concentration dependent. Personal care products containing formaldehyde and related preservatives have been deemed safe when used as directed.[6] Additionally, this preservative is typically added to cosmetics as formaldehyde-releasing compounds that decompose slowly over time (or with changes in its environment like increased temperature or exposure to air) resulting in the long-term preservation of the product.[7] While inhalation of formaldehyde has been linked with several different types of cancers of the respiratory tract, classifying it as a carcinogen by the World Health Organization, its use in personal care products appears to be low enough to be considered safe.[8,9] However, its use in hair smoothing products such as Brazilian blowouts can be hazardous since much larger amounts of formaldehyde are released during the process, potentially affecting the health of those who frequently use such products (such as hair stylists).[6] Nail hardening products can also be cause for concern due to higher formaldehyde concentrations. These products often list it as methylene glycol in the ingredients list.

If you have experienced sensitization to formaldehyde and its related ingredients, it would be prudent to check your product labels for the following: formalin, quaternium-15, DMDM hydantoin, methylene glycol, methylene oxide, formol, methanal, methyl aldehyde, methaldehyde, oxomethane, and oxymethylene.[9] The Food & Drug Administration (FDA) does not regulate the amount of these ingredients used; however, they do require that products must be safe.[10] While alternatives to formaldehyde and its related compounds exist, they are not commonly used in the industry partly due to the lack of consumer demand and partly due to the lower cost of formaldehyde.[11] Regardless, it is generally agreed upon that it is better to have a product containing formaldehyde than it is to have a product contaminated with harmful microbes. However, as more alternative preservatives come to market, the use of formaldehyde-related ingredients will likely decrease. 

Table 1. Formaldehyde Related Ingredients 



DMDM hydantoin

Methylene glycol

Methylene oxide


Methyl aldehyde




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