PRESERVATIVE
Sodium Metabisulfite
- preservative
A reducing agent that keeps a formula from discolouring.
- products in our library
- 82
- of researched products
- 1%
- on the label, in our scalp treatments
- usually #26
- most common in
- Scalp treatment
- in water
- Water-soluble
At a glance
Four things worth knowing about how this ingredient behaves on hair.
How much of it is left on hair between washes.
What it takes to get it off the hair again.
What it is in the formula to protect.
Where it sits on the labels we have, in the category it appears in most.
| Property | Level | Out of |
|---|---|---|
| Buildup risk | Low | 1 of 5 |
| Rinse-out behaviour | Rinses clean | 5 of 5 |
| Role | Keeps water-based formulas | 4 of 5 |
| Prominence | Secondary | 2 of 5 |
What it does for a formula
What Sodium Metabisulfite does
The general function first, then how the role changes by product type where we have researched it.
Protects the oils in the bottle rather than the hair.
Anything with water in it needs one, over the life of the bottle.
Water alone removes it, so it does not accumulate between washes.
Charge
Charge is not recorded for this ingredient.
Solubility
Rinses out with water alone, so it does not build up on hair between washes.
Where it appears
Where it appears
One row per product category in our library: how many products list it, what share of that category that is, and where it typically sits on the label.
| Product type | How common | Typical position on label ? |
|---|---|---|
Scalp treatment
27 products
|
secondary · #26 | |
Shampoo
20 products
|
secondary · #40 | |
Conditioner
14 products
|
secondary · #36 | |
Mask / treatment
9 products
|
secondary · #45 | |
Co-wash
3 products
|
secondary · #24 | |
Dry shampoo
2 products
|
secondary · #22 | |
Finisher: oil
1 product
|
secondary · #13 | |
Heat protectant
1 product
|
secondary · #12 | |
Leave-in
1 product
|
secondary · #20 | |
Styler: curl cream
1 product
|
secondary · #67 |
3 more product types
| Product type | How common | Typical position on label ? |
|---|---|---|
Styler: hairspray
1 product
|
secondary · #37 | |
Styler: mousse
1 product
|
secondary · #24 | |
Styler: paste
1 product
|
secondary · #50 |
| Product type | Products | Share of category | Median position | Earliest position | Band |
|---|---|---|---|---|---|
| Scalp treatment | 27 | 9% | 26 | 3 | secondary |
| Shampoo | 20 | 1% | 40 | 24 | secondary |
| Conditioner | 14 | 1% | 36 | 26 | secondary |
| Mask / treatment | 9 | 2% | 45 | 14 | secondary |
| Co-wash | 3 | 3% | 24 | 16 | secondary |
| Dry shampoo | 2 | 2% | 22 | 22 | secondary |
| Finisher: oil | 1 | 0% | 13 | 13 | secondary |
| Heat protectant | 1 | 0% | 12 | 12 | secondary |
| Leave-in | 1 | 0% | 20 | 20 | secondary |
| Styler: curl cream | 1 | 0% | 67 | 67 | secondary |
| Styler: hairspray | 1 | 0% | 37 | 37 | secondary |
| Styler: mousse | 1 | 0% | 24 | 24 | secondary |
| Styler: paste | 1 | 1% | 50 | 50 | secondary |
We have not researched differences by product type yet. The reading below comes from where it sits on the labels in our library.
Position footprint
Every listing in our library, by position on the label.
| Positions | Zone | Listings |
|---|---|---|
| 1-3 | Leading | 1 |
| 4-8 | Supporting | 1 |
| 9-15 | Secondary | 7 |
| 16-25 | Lower | 15 |
| 26+ | Trace | 58 |
How to read this
US labelling rules put ingredients above 1% in descending order of amount; below 1% they may be listed in any order.
So position tells you about relative amount only above that line, and we never convert a position into a percentage.
Why it matters to shoppers
What seeing this ingredient tells you, what it does not, and the limits of our own method.
- oils that do not turn rancid in the bottle
- a product that keeps over its shelf life
- a rinse-clean feel
- an exact safety score (we do not publish one for any ingredient)
- how a finished product performs, which depends on the whole formula, not one line of it
- the exact percentage in a bottle, because label position never converts into a number
- a secondary antioxidant, listed below the main ingredients in our scalp treatments
- it was on the printed ingredient list of every product we counted (we read labels, not marketing copy)
- that the product would be better without one
- that a product is right or wrong for you
We do not publish safety scores or hazard grades. Where a regulator has published a restriction or a use condition, we state it and cite it; otherwise we describe what the ingredient does and stop.
Commonly paired with
The ingredients that most often appear alongside this one in our library. We leave out the near-universal ones, because they pair with everything and tell you nothing.
- Camellia Sinensis (Green Tea) Leaf Extract · 45
- Propanediol · 43
- Ethylhexylglycerin · 42
- Caprylyl Glycol · 40
- Butylene Glycol · 36
- Tocopherol · 35
- Benzyl Alcohol · 33
- Larix Europaea Wood Extract · 32
- Glycine · 32
- Sodium Hydroxide · 30
The number beside a name is how many products in our library list both.
These ingredients tend to appear together to keep the formula stable, carry the formula and let it dry, and soften the strand.
Found in these products
The most prominent placements first. The badge is the position on that product’s own ingredient list.
Pura d'or · Scalp treatment
Hair Thinning Therapy Energizing Scalp Serum
#3 on the label · $6.25/oz
Pura d'or · Scalp treatment
Advanced Peptide Hair and Scalp Serum Hair Regrowth Tonic
#5 on the label · $19.99/oz
Kreyòl Essence · Scalp treatment
Save Our Scalp Serum Squeeze Bottle
#9 on the label · $30.77/oz
Kreyòl Essence · Scalp treatment
Save Our Scalp: Peptide + Clove Density Treatment Spray
#11 on the label · $22.35/oz
Olaplex · Heat protectant
Volumizing Blow Dry Mist
#12 on the label · $5.95/oz
Bosley · Scalp treatment
Rejuvenating Scalp Scrub
#13 on the label · $5.49/oz
Maria Nila · Finisher
Cica Oil
#13 on the label · $12.10/oz
Sienna Naturals · Scalp treatment
D.N.A. Scalp Serum for Thinning Hair
#13 on the label · $42.00/oz
L'Oreal Professionnel · Mask / treatment
[Keratin Alpha Sleek] Anti-Frizz Smooth Transformer for Smooth Hair
#14 on the label · $5.97/oz
Keracolor · Co-wash
Cleansing Conditioner
#16 on the label · $1.67/oz
Kreyòl Essence · Scalp treatment
Save Our Scalp: Clarify Shampoo + Bamboo Scalp Scrub
#18 on the label · $5.93/oz
Coco & Eve · Scalp treatment
Tripeptide Hair Density Serum
#19 on the label · $17.24/oz
See all 82 products in the library that list Sodium Metabisulfite
Identity
What this entry is, and what our references call it.
No public-domain structure depiction is available for this entry.
Sodium Metabisulfite
- antioxidant
- sodium metabisulfite
For your hair?
Whether Sodium Metabisulfite matters for your hair depends on your hair.
82 products in our library list itWhat this ingredient does, and where it sits on the labels we have researched.
A verdict on any product that contains it, and never a safety grade.
We do not physically test your hair. Everything above comes from the ingredient lists in our library and from published references. The consultation is what turns it into a plan.
References
Seed entry, sourcing in progress Written from our reference work; primary sourcing is still being attached.
No published source is attached to this entry yet.
How this page was made
- Every number above is counted from the ingredient lists in our own product library: 82 of 6816 researched products list this ingredient. Nothing on this page is written per ingredient.
- The dots are levels, not scores. Each one comes from what kind of ingredient it is (its chemical class, charge and solubility) or from where it sits on the labels we have.
- US labelling rules put ingredients above 1% in descending order of amount; below 1% they may be listed in any order. Position tells you about relative amount only above that line, and we never convert a position into a percentage.
- The prominence bands (leading, supporting, secondary) are the same ones the product pages use to read a single label, applied here to the median position across a category.
- We do not publish safety scores or hazard grades. Where a regulator has published a restriction or a use condition, we state it and cite it; otherwise we describe what the ingredient does and stop.
- Identifiers and references appear only when a published source is attached to this entry. Without one, we leave the row out rather than fill it in.
- This is cosmetic information, not medical advice, and nothing here diagnoses or treats a health condition.
- Entry last updated 2026-09-22. Product-page methodology: the product library.
