So
Sodium Hydroxide
Sodium Hydroxide
A strong base used in tiny amounts to fine-tune a formula's pH. The high spot on a lot of ingredient lists worries people, but the role is mundane.
What it does
Sodium hydroxide is a pH adjuster. Formulators add a very small quantity to bring a finished product to its target pH — important for actives like vitamin C or exfoliating acids that only work in a specific range, and for the skin's own comfort zone. By the time the product is on shelf it has reacted and been neutralized, so the amount present is trace. Seeing it near the end of an ingredient list is normal and not a cause for concern on its own.
Also known as
lye, caustic soda
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