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Ingredient on hair labels

Sodium Metabisulfite

TheWashDay editorial · Updated · From the EU ingredient register and the makers’ own labels · How we match names

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Sodium Metabisulfite is on 3 of the 177 hair-product labels we compare, from 3 makers. Its uses in the EU ingredient register are antioxidant, preservative and reducing. None of these labels names it among its first five ingredients.

See it on each label Products without it

What it is

In the register’s words: “Sodium Metabisulfite is the inorganic salt.”

EU register name (INCI)
SODIUM METABISULFITE
CAS number
7681-57-4 / 7757-74-6
EC number
231-673-0 / -

What the register lists it for

These are the uses the European Commission’s CosIng register lists for Sodium Metabisulfite in any cosmetic, hair roles first. They say why a maker might add it, not what it does in one formula, and they aren’t a safety rating.

Antioxidant

Slows the oxygen damage that makes oils go rancid in the bottle. Vitamin E (tocopherol) is the common one.

Register definition: “Inhibiting reactions promoted by oxygen, thus avoiding oxidation and rancidity.”

Preservative

Stops bacteria, mold and yeast growing in the bottle. EU law allows only the preservatives on its own list for this role.

Register definition: “Exclusively or mainly intended to inhibit the development of micro-organisms in the cosmetic product. All authorised preservatives are substances in the positive list of Annex V to the Cosmetics Regulation 1223/2009.”

Reducing

Changes another ingredient chemically by adding hydrogen; in hair products, mostly in perms and colors.

Register definition: “Changing the chemical nature of another ingredient by adding hydrogen (or removing oxygen).”

Where it sits on each label

US labels list ingredients from most to least, except that those at 1% or less may follow in any order. A name near the top is a large part of the formula. A label doesn’t mark where the 1% point falls, so further down, the order says little about how much is in it.

Every label, product by product (3)

Each line runs from the first name on a label to the last; a dot is where this ingredient sits. Makers change formulas now and then; if the list on your bottle differs, go by your bottle.

Your next step

Find products without Sodium Metabisulfite Check every name on your own label All ingredients on the labels we compare

Other antioxidant ingredients on these labels

Updated · The name, numbers and uses come from the European Commission’s CosIng entry (CC BY 4.0); we write the uses in US spelling and put the hair ones first. The labels are each maker’s own. The order rule is the FDA’s Cosmetics Labeling Guide. All our sources are on the Sources page.