Researched by Helena DeMaria-Williams
Formula IngredientPreservativeINCI: Sodium Benzoate
Sodium benzoate is a widely used cosmetic preservative derived from benzoic acid, functioning as the sodium salt of benzoic acid. It works by inhibiting microbial growth — particularly fungi and some bacteria — by disrupting cell membrane transport and interfering with intracellular pH, making it most effective in acidic formulations (pH 3–5). Because it lacks broad-spectrum potency on its own, it is typically paired with other preservatives such as potassium sorbate to achieve full-spectrum protection.
Category
Preservative
Irritation Risk
Low
Skin Types
all skin types, oily, dry, combination, normal
preserving product stability, preventing microbial and fungal contamination, extending shelf life
At typical cosmetic concentrations (up to 0.5% per EU Annex V), sodium benzoate is considered non-irritating for most skin types. However, individuals with a known benzoic acid or balsam of Peru allergy may experience contact sensitisation. It is listed in EU Annex V (permitted preservatives, entry V/1) with a maximum concentration of 0.5% in finished products. Cross-reactivity with fragrances and cinnamic derivatives is possible in sensitive individuals.
Sodium benzoate does not increase photosensitivity. No sun protection precautions are required specifically due to its presence in a formulation.
Sodium benzoate is generally considered low risk in cosmetics due to minimal systemic absorption from topical use. However, as a food additive it has been flagged by some researchers for potential effects at high oral doses, and in combination with vitamin C (ascorbic acid) it can theoretically form trace amounts of benzene — a known carcinogen — under heat or UV exposure. While topical formulations present far lower exposure than dietary intake, a cautious approach is advised during pregnancy; opt for products where it appears low on the ingredient list. No formal reproductive toxicity studies specific to topical cosmetic use have established a definitive risk rating (Sources: EWG Skin Deep; Paula's Choice ingredient dictionary).
Sodium benzoate is a widely used cosmetic preservative derived from benzoic acid, functioning as the sodium salt of benzoic acid. It works by inhibiting microbial growth — particularly fungi and some bacteria — by disrupting cell membrane transport and interfering with intracellular pH, making it most effective in acidic formulations (pH 3–5). Because it lacks broad-spectrum potency on its own, it is typically paired with other preservatives such as potassium sorbate to achieve full-spectrum protection.
Individuals with benzoic acid allergy, balsam of Peru allergy, known preservative sensitivity; caution if combining with high-dose vitamin C in acidic formulations should review the considerations above before use.