What it is
This is a water-soluble sulfonated benzotriazole that absorbs UV energy, allowing it to act as a light stabilizer that protects sensitive dyes, fragrances, and active ingredients from fading or breaking down. In a sunscreen it is used to help maintain the integrity and appearance of the product rather than as a labeled sunscreen active. Its water solubility lets it function in the aqueous phase of a formula.
Safety & warnings
Used at the low levels typical for a formula stabilizer, this ingredient is generally well tolerated. It is not a known fragrance allergen and is not associated with comedogenicity.
Origin & sourcing
Synthetic, derived from benzotriazole chemistry and supplied as the sodium sulfonate salt.
Questions everyone asks
Is this a sunscreen active?
In these products it functions as a formula light stabilizer and UV absorber that protects the product itself, not as a labeled sunscreen active.
Why protect the formula from light?
UV exposure can fade colors and degrade fragrances and actives; a light stabilizer helps keep the product stable over its shelf life.