Benzoic Acid

Recognized as a safe, well-tolerated preservative

Also functions as a pH adjuster in skin care formulations

Naturally aromatic but usually isn’t used in high enough potency to impart scent in skin care products

Needs to be used in combination with other preservatives for optimum protection

Benzoic acid functions as a preservative and pH adjuster in skin care formulations. It is known to be well tolerated and unlikely to cause sensitization in amounts commonly used. It should be combined with other preservatives in order to prevent broader contamination, particularly in water-based formulas. Benzoic acid primarily serves to reduce growth of fungi, such as yeast or mold. It is not considered very active against bacteria.

When used as a preservative, it is strongly suggested that the pH of the final formulation be below six for maximum efficacy.

In 2017, the Cosmetic Ingredient Review Expert Panel looked at personal care products using up to 5% benzoic acid and ruled that this ingredient is safe in cosmetic use. When used as a preservative in skin care products, you’ll find benzoic acid in much lower concentrations, usually between 0.2–0.5%. Note: While benzoic acid can be aromatic in nature, it usually isn’t used in high enough potency to deliver a detectable scent in skin care products.

Fun fact: Benzoic acid is naturally found in fruits (berries), nuts, spices and vegetables. Rich sources include strawberries, cayenne pepper, mustard, prunes, cinnamon, and cloves. Benzoic acid is also added to food products as a preservative.