Scan the back of almost any skincare product on a UK shop shelf, and you will find the same few names quietly occupying the bottom lines of the ingredient list. One of those is dehydroacetic acid. It never receives top billing on the packaging, and it is certainly not the reason you bought the formula, yet it is precisely why that product remains safe to use months after you first unsealed it.
What is dehydroacetic acid?
Dehydroacetic acid (frequently abbreviated to DHA in cosmetic formulation circles — not to be confused with dihydroxyacetone, the active agent in fake tan) is a synthetic organic acid used as a cosmetic preservative. On INCI labels, it appears either as dehydroacetic acid or as its water-soluble salt form, sodium dehydroacetate, which is what most water-based products utilise.
Functionally, it operates as a broad-spectrum antimicrobial: it halts the proliferation of bacteria, moulds, and yeasts. In water-based products — whether a cleanser, serum, or cream — this protection is critical. Water provides an ideal breeding ground for microbes; without a reliable preservative system, a jar of moisturiser can turn into a biological habitat within weeks of opening.
Crucially, dehydroacetic acid is not an active. It offers no exfoliating, brightening, or anti-ageing effects, and it carries a zero comedogenic rating (meaning it will not clog pores). Its sole responsibility is maintaining product safety and stability.
Is it safe?
In the UK, cosmetic preservatives are governed by EU-derived regulations retained in British law. Under this framework, a substance may only serve as a preservative if listed on the approved schedule, subject to strict conditions. Dehydroacetic acid and its salts are permitted at a maximum concentration of 0.6% (expressed as acid). They are prohibited in aerosol sprays solely to avoid inhalation exposure, not due to skin safety concerns.
Safety evaluations from major bodies, including the European Union's Scientific Committee on Consumer Safety (SCCS) and the Cosmetic Ingredient Review (CIR) Expert Panel, confirm that dehydroacetic acid is safe for topical use within permitted limits. Clinical data demonstrates that it is non-irritating and non-sensitising at these concentrations, making it suitable for all skin types, including sensitive skin.
Additionally, dehydroacetic acid is biodegradable and approved by natural certification bodies such as COSMOS and Ecocert. This often surprises consumers who assume "preservatives" and "natural certifications" cannot coexist; in reality, mild organic acids allow natural products to remain safely preserved without resorting to prohibited synthetic agents.
What are its benefits for skin?
While dehydroacetic acid delivers no direct cosmetic transformations, its indirect benefits are essential:
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Ensures product safety: Prevents microbial overgrowth and fungal contamination, eliminating the risk of applying spoiled formulas to broken or compromised skin.
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Protects active ingredients: Delicate actives like vitamin C and exfoliants degrade rapidly in unstable environments. Effective preservation ensures your key ingredients remain active throughout the product's shelf life.
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Enables milder preservation systems: Because it works effectively at low concentrations against both bacteria and fungi, formulators can avoid heavy preservative blends. For sensitive skin, this translates to a reduced risk of overall irritation.
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High skin tolerance: Non-sensitising, non-comedogenic, and well-tolerated across diverse skin conditions.
Dehydroacetic Acid in REFORM Skincare Products
REFORM Skincare incorporates dehydroacetic acid and sodium dehydroacetate across its water-based formulations to ensure microbial stability.
| Product | Category |
| Glycolic Acid Foaming Cleanser | Exfoliating cleanser |
| Salicylic Acid Foaming Cleanser | Cleanser for oily skin |
| Gentle Hydrating Crème Cleanser | Cleanser for dry skin |
| Repair & Renew Gel | Resurfacing treatment |
| HYAL • Vitamin C + E Serum | Antioxidant serum |
| Retinol 1% Crème | Anti-ageing night cream |
Note: You will not find dehydroacetic acid in purely oil-based or anhydrous formulas, as these environments do not support microbial growth in the same way and do not require water-phase preservation.
When reviewing REFORM ingredient lists, note that full breakdowns group dehydroacetic acid under "preservative" or "stability" headings rather than alongside headline actives. All formulations strictly adhere to the regulatory concentration limit of 0.6% or lower.
Dehydroacetic acid is a well-researched, highly effective preservative that works quietly behind the scenes. It will not overhaul your complexion on its own, but it guarantees that the vitamin C, glycolic acid, and retinol in your routine remain safe, stable, and active down to the very last drop.
