Dehydroacetic Acid

What it is

Dehydroacetic acid is a synthetic pyranone that behaves like a stronger relative of sorbic acid. It is mainly antifungal, works best in mildly acidic formulas, and is frequently paired with benzyl alcohol in preservative blends marketed as 'natural-compatible'. Its sodium salt, sodium dehydroacetate, is the more water-soluble version and falls under the same EU entry.

What it does well

• Good mould and yeast control in acidic and natural-positioned formulas

  It is widely used as the antifungal half of preservative blends that avoid parabens and isothiazolinones, particularly in mask essences and gels.

  Moderate evidence

• Very low reported rate of skin reactions

  Reports of allergy are sparse (a handful of case reports rather than population-level signals) despite widespread use in cosmetics and food.

  Moderate evidence

Worth knowing

• Occasional allergic contact dermatitis

  Sodium dehydroacetate was described in Dermatitis in 2012 as an 'emerging allergen' on the basis of case reports. It remains uncommon, but it is documented.

  Matters most toPeople with known preservative allergy or unexplained cosmetic dermatitis.

• Not permitted in aerosol sprays

  The EU restriction excludes aerosol dispensers because of concerns about inhalation exposure rather than skin contact. It has no bearing on face masks, which are not sprayed.

  Matters most toNobody using face masks; the restriction applies to spray formats.

Where the EU stands

Sources (1)

Every link goes to the original: a journal, a PubMed record or an EU document.

1. [1]
   Sodium dehydroacetate: an emerging allergen

   Dermatitis · 2012 · doi:10.1097/DER.0b013e31826f5b86

   A case-based report identifying sodium dehydroacetate as a newly recognised, though uncommon, cause of allergic contact dermatitis.