Sodium Dehydroacetate

Sodium dehydroacetate is a preservative/antimicrobial typically used around ~0.2–0.6% in leave-on and rinse-off products. Human patch testing and post-market experience generally show low rates of irritation, but preservatives can still provoke stinging or mild irritant dermatitis in highly reactive or barrier-impaired skin (e.g., eczema), especially with cumulative exposure from multiple products. Given its preservative role and the need to err on patient safety for sensitive populations, I rate it as mild rather than “gentle.” Safety Notes: In commercial cosmetics, sodium dehydroacetate is most often used as a preservative in leave-on and rinse-off products around ~0.1–0.6%, with low-end usage (~0.05%) typically appearing in multi-hurdle systems (e.g., combined with organic acids/chelators) or low-risk rinse-off formulas. High-strength consumer-available products (including some “preservative booster” concentrates and water-rich formulations built around dehydroacetate systems) can reach about 1.0%, which aligns with common EU preservative use limits for dehydroacetic acid/dehydroacetates and reflects the upper end seen in OTC formulations rather than prescription/professional-only products.