What it is
Propyl gallate is a synthetic antioxidant formed by esterifying gallic acid with propanol, and it is widely used in both foods and cosmetics. In sunscreens and moisturizers it protects unsaturated oils, fragrances, and sensitive actives from oxidative breakdown, helping maintain color and stability over time. It is typically used at very low concentrations and is often combined with other antioxidants.
Safety & warnings
Propyl gallate is generally recognized as safe at the low levels used in cosmetics, but it is a documented contact allergen and can cause allergic contact dermatitis in sensitized individuals. People with a known gallate or balsam-related sensitivity should be aware of its presence. It is not considered comedogenic and is not a fragrance allergen.
Origin & sourcing
Synthetic, made by esterifying gallic acid with propyl alcohol; gallic acid itself can be sourced from plant tannins.
History
Propyl gallate has a long record of use as a food and cosmetic antioxidant and is one of the established gallate esters used to retard oxidation.
Questions everyone asks
Why is propyl gallate used in sunscreen?
It is an antioxidant that helps keep oils and other oxidation-sensitive ingredients from breaking down, supporting the stability of the formula.
Can propyl gallate cause skin reactions?
It is a known contact allergen and can cause allergic contact dermatitis in sensitized people, though it is generally well tolerated at cosmetic levels.