Sodium Metabisulfite Middel Preservative No known benefits Sodium Metabisulfite at a glance Used as a preservative and stabiliser in cosmetic formulations Also offers antioxidant properties In hair care, it acts as a reducing agent that alters the structure of hair Described as colourless crystals or a white to yellowish crystalline powder in raw material form Sodium Metabisulfite description Sodium metabisulfite is used as a preservative and stabiliser in cosmetic formulations. This synthetic ingredient also offers antioxidant properties. In hair care, it functions as a reducing agent that alters the structure of hair. Suppliers of sodium metabisulfite describe it as colourless crystals or a white to yellowish crystalline powder in its raw material form. In 2013 the Cosmetic Ingredient Review Expert Panel deemed sodium metabisulfite safe as used in cosmetic formulations (their report looked at skin care products using less than 1% concentrations). Its safety status was reaffirmed in 2020. Research indicates those with allergies/sensitivities to sulfite ingredients should be aware of potential sensitisation to sodium metabisulfite.