SPF Scout · Ingredient

Sodium Hydroxide

Buffering (holds the formula at a set acidity)Denaturant (makes alcohol undrinkable)other

CAS 1310-73-2

EU regulatory status

  • Restricted in cosmetic products in the EU

    Annex III (substances subject to restrictions), entry 15a — EU Cosmetics Regulation (EC) No 1223/2009, as recorded in CosIng.

This status describes European Union cosmetics law — which substances may be used in cosmetic products sold there, and under what conditions. Regulations differ by region. It is not a statement about any specific product, and it does not predict whether your skin will react.

What this ingredient generally does

Sodium Hydroxide is a strongly alkaline ingredient used in tiny amounts to fine-tune a formula's acidity (buffering). This keeps the product's pH steady. It can also act as a denaturant, altering another substance so it stays fit for use in cosmetics rather than being consumed.

Reviewed before publication. This note describes function in a formulation — nothing else.

Published formulations that list this ingredient

These are the formulations currently published in the SPF Scout catalog whose stored ingredient declaration includes this ingredient. It is not a list of every product on the market, and the order carries no meaning.

Checking this against your own list

You can select this ingredient in the SPF Scout app as one to flag. The app compares your selections against a product's stored declaration on your device; your list never reaches this website.

This comparison does not predict whether your skin will react.

Where this information comes from

Ingredient names, CAS numbers and recorded functions come from SPF Scout’s curated ingredient dictionary, grounded in CosIng, the European Commission’s Cosmetic Ingredient Database. Content © European Union, reused with acknowledgement.

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