Cosmetic ingredient

SODIUM SULFITE

Sodium sulfite, listed as SODIUM SULFITE, is an inorganic salt also known as disodium sulfite. It belongs to the sulfite family, made up of sulfur-and-oxygen compounds that can react readily under certain chemical conditions. It is not a botanical extract or an oil; it is a defined substance used in small amounts in particular formulations.

2D molecular structure

CAS number

7757-83-7

EC number

231-821-4

Molecular formula

Na2O3S

Molecular weight

126.05

Chemical name

Sodium sulphite

InChIKey

GEHJYWRUCIMESM-UHFFFAOYSA-L

SODIUM SULFITE: what it is

Its name can be confused with sodium metabisulfite, but they are not the same ingredient. They belong to the same chemical family while having different compositions and uses. The distinction matters in hair products, where the sulfite form can take part in processes intended to temporarily alter how the hair fibres are arranged.

SODIUM SULFITE: what it does in cosmetics

In cosmetics, sodium sulfite can work as a reducing agent. In hair-waving or straightening products, this helps enable the controlled change in hair shape during the procedure; the result also depends on the technique, contact time, and the other ingredients in the product. It can also act as an antioxidant, helping limit oxidation reactions that could change a preparation.

A safety review of sulfites in cosmetics describes their use mainly in hair-care products and does not show that sodium sulfite on its own treats hair loss, dandruff, damage, or scalp disease. For someone reading an ingredient list, its presence points to a chemical job within the formula, not to a stand-alone hair-care claim.

SODIUM SULFITE: conditions and care

In the European Union, inorganic sulfites, including sodium sulfite, are limited to 0.2% calculated as free SO₂ in the cosmetic product. This is a composition limit set for that family of substances.

Use limits