Sodium Benzoate
A widely used, food-grade preservative that keeps water-based skincare free from mould and yeast, so it stays fresh once opened.
sodium benzoate, benzoic acid, sodium salt, E211
What it does
Sodium benzoate is a food-grade preservative: the sodium salt of benzoic acid, which occurs naturally in fruits such as cranberries and plums, although the ingredient itself is made synthetically. It is one of the most widely used preservatives in skincare, helping water-based formulas stay free from mould, yeast and bacteria, so products remain stable on the shelf and fresh once opened.
How it works
In slightly acidic formulas, sodium benzoate converts to benzoic acid, which enters microbial cells and disrupts their metabolism so they can't multiply. It is particularly effective against yeasts and moulds, so it is usually paired with other preservatives, such as potassium sorbate or phenoxyethanol, for broad protection. It also acts as an anticorrosive, helping protect metal packaging such as tubes and aerosol cans.
MG says
Sodium benzoate is an essential ingredient in ensuring the shelf life of a product: it is one of the preservatives that keep water-based formulas, from Biologique Recherche's Lotion P50 to Augustinus Bader's creams, free from mould and yeast once opened. Use products within the time the brand recommends after opening.
Cautions
Sodium benzoate is used at low concentrations and rarely irritates, although, like any ingredient, it can occasionally cause stinging or a reaction in very sensitive skin. You may read that it shouldn't be combined with vitamin C: that concern comes from soft drinks, where the two can form trace amounts of benzene under heat and light. For skincare, good formulation and storage, somewhere cool and out of direct sun, are the sensible precautions.
