Formaldehyde
Reviewed by Kate · Last updated 14 Aug 2026
A preservative that prevents microbial growth in cosmetic formulations
Best For Skin Types
All
Addresses
Usage Frequency
As tolerated
What Is Formaldehyde?
Formaldehyde is a small organic molecule used as a preservative in cosmetics and skincare products. It works by preventing the growth of bacteria, fungi and other microorganisms that could otherwise contaminate a product during storage and use.
In skincare formulations, formaldehyde is typically used at low concentrations to extend shelf life and maintain product safety. It is one of several preservative options available to formulators, each with different efficacy profiles and tolerability considerations.
How It Works
Formaldehyde is a broad-spectrum antimicrobial agent. It works by interfering with microbial cell function and preventing reproduction, thereby stopping product degradation and spoilage caused by bacterial or fungal growth.
The effectiveness of formaldehyde as a preservative depends partly on the formulation type (aqueous solutions, emulsions, or hydrogels may show different preservation efficiency) and the concentration used.
Clinical Evidence & References
Formaldehyde is an established preservative with a long history of use in cosmetics. However, individual tolerance varies. Some research suggests that formaldehyde exposure can trigger irritation or worsen symptoms in people with eczema or contact sensitivity.
The safety profile of formaldehyde in cosmetics is regulated in the EU and other regions, with maximum allowable concentrations set to minimise adverse effects. Evidence suggests that skin penetration of formaldehyde from cosmetic products is influenced by formulation type, though further research would help clarify safe exposure thresholds in real-world use.
How to Use
If you use a product containing formaldehyde and notice signs of irritation, redness or worsening of existing eczema, discontinue use and patch test before reintroduction. Those with known sensitivity to preservatives may prefer formulations using alternative preservative systems.
Safety & Precautions
Frequently Asked Questions
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