PH ADJUSTER
Sodium Hydroxide
- pH adjuster
A strong base used in trace amounts to raise pH; fully neutralised in the finished product.
- products in our library
- 595
- of researched products
- 15%
- on the label, in our shampoos
- usually #21
- most common in
- Shampoo
- in water
- Water-soluble
At a glance
Four named levels, read from this ingredient’s chemical class, its charge, its solubility, or where it sits on the labels we have. More dots means more of the property named — never “better”.
How much of it is left on hair between washes.
What it takes to get it off the hair again.
The housekeeping this class does.
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 |
| Job | Sets acidity | 3 of 5 |
| Prominence | Secondary | 2 of 5 |
What it does for a formula
What Sodium Hydroxide does
The general function first, then how the role changes by product type where we have researched it.
The cuticle lies flatter on the acidic side; this is how a formula gets there.
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 — it does not accumulate 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 ? |
|---|---|---|
Shampoo
244 products
|
secondary · #21 | |
Conditioner
133 products
|
secondary · #23 | |
Leave-in
56 products
|
secondary · #21 | |
Mask / treatment
43 products
|
secondary · #22 | |
Styler: mousse
22 products
|
secondary · #19 | |
Scalp treatment
18 products
|
secondary · #19 | |
Styler: gel
16 products
|
secondary · #22 | |
Heat protectant
13 products
|
secondary · #18 | |
Co-wash
12 products
|
secondary · #24 | |
Styler: smoothing cream
9 products
|
secondary · #22 |
11 more product types
| Product type | How common | Typical position on label ? |
|---|---|---|
Styler: paste
6 products
|
secondary · #19 | |
Styler: volumizer
6 products
|
secondary · #24 | |
Finisher: serum
5 products
|
secondary · #30 | |
Styler: curl cream
4 products
|
secondary · #23 | |
Styler: hairspray
3 products
|
secondary · #27 | |
Finisher: anti frizz finish
1 product
|
secondary · #43 | |
Finisher: end oil
1 product
|
secondary · #40 | |
Finisher: oil
1 product
|
secondary · #22 | |
Styler: edge control
1 product
|
secondary · #27 | |
Styler: refresh spray
1 product
|
secondary · #20 | |
Styler: texture spray
1 product
|
secondary · #17 |
| Product type | Products | Share of category | Median position | Earliest position | Band |
|---|---|---|---|---|---|
| Shampoo | 244 | 30% | 21 | 3 | secondary |
| Conditioner | 133 | 19% | 23 | 8 | secondary |
| Leave-in | 56 | 13% | 21 | 5 | secondary |
| Mask / treatment | 43 | 11% | 22 | 9 | secondary |
| Styler: mousse | 22 | 16% | 19 | 11 | secondary |
| Scalp treatment | 18 | 11% | 19 | 11 | secondary |
| Styler: gel | 16 | 10% | 22 | 9 | secondary |
| Heat protectant | 13 | 9% | 18 | 7 | secondary |
| Co-wash | 12 | 12% | 24 | 10 | secondary |
| Styler: smoothing cream | 9 | 16% | 22 | 8 | secondary |
| Styler: paste | 6 | 7% | 19 | 8 | secondary |
| Styler: volumizer | 6 | 9% | 24 | 14 | secondary |
| Finisher: serum | 5 | 6% | 30 | 20 | secondary |
| Styler: curl cream | 4 | 4% | 23 | 8 | secondary |
| Styler: hairspray | 3 | 3% | 27 | 19 | secondary |
| Finisher: anti frizz finish | 1 | 4% | 43 | 43 | secondary |
| Finisher: end oil | 1 | 11% | 40 | 40 | secondary |
| Finisher: oil | 1 | 1% | 22 | 22 | secondary |
| Styler: edge control | 1 | 6% | 27 | 27 | secondary |
| Styler: refresh spray | 1 | 8% | 20 | 20 | secondary |
| Styler: texture spray | 1 | 2% | 17 | 17 | secondary |
No product-type differences have been researched yet — the reading below is computed 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 | 24 |
| 9-15 | Secondary | 146 |
| 16-25 | Lower | 258 |
| 26+ | Trace | 254 |
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.
Who should pay attention
Conditional formulation guidance, scoped to a hair condition and to the positions where it is meaningful. It is not a conclusion about any finished product, and not a conclusion about you.
The alkali half of a pH-adjusting pair, used in small amounts to bring a formula up to its target rather than to make it alkaline. Alkaline conditions raise the fibre's surface charge and lift the scales — but the finished pH is not on the label.
Researched for this ingredient, with sources listed below.
Why it matters to shoppers
What this ingredient is evidence of, what it is not evidence of, and what our own method can and cannot tell you.
- a formula set to the acidity the cuticle prefers
- a rinse-clean feel
- an exact safety score — we do not publish one, for any ingredient
- how a finished product performs by itself — that is the whole formula, not one line of it
- the exact percentage in a bottle — label position never converts into a number
- a secondary pH adjuster, listed below the main ingredients in our shampoos
- it was on the label of every product we counted — we read printed ingredient lists, not marketing copy
- 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
Ingredients that appear alongside this one most often in our library. Near-universal ingredients are excluded — they pair with everything and tell you nothing.
- Sodium Chloride · 216
- Guar Hydroxypropyltrimonium Chloride · 194
- Tocopherol · 193
- Behentrimonium Chloride · 190
- Benzyl Alcohol · 190
- Cocamidopropyl Betaine · 171
- Propylene Glycol · 159
- Hexyl Cinnamal · 158
- Cetrimonium Chloride · 150
- Isopropyl Alcohol · 148
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, improve feel after rinsing, and deliver a stated effect.
Found in these products
The most prominent placements first. The badge is the position on that product’s own ingredient list.
Pura d'or · Shampoo
Apple Cider Vinegar Thin2Thick Clarifying and Detoxing Shampoo
#3 on the label · $1.00/oz
It's a 10 · Leave-in
Miracle Blow Dry H2O Shield
#5 on the label · $8.00/oz
Kerastase · Shampoo
Kerastase Genesis Bain Hydra-Fortifiant Shampoo
#5 on the label · $5.17/oz
Pura d'or · Shampoo
Advanced Therapy Anti-Hair Thinning Shampoo
#5 on the label · $1.47/oz
Kerastase · Shampoo
Kerastase Gloss Absolu Bain Hydra-Glaze Shampoo
#6 on the label · $4.78/oz
Matrix · Shampoo
Instacure Build-A-Bond Mighty Bonds Shampoo
#6 on the label · $1.53/oz
Matrix · Shampoo
Total Results High Amplify Volumizing Shampoo
#6 on the label · $1.78/oz
Redken · Shampoo
Acidic Bonding Concentrate Shampoo
#6 on the label · $3.36/oz
Redken · Shampoo
Extreme Length Shampoo
#6 on the label · $2.87/oz
Biolage · Scalp treatment
Scalp Sync Purifying & Exfoliating Concentrate
#7 on the label · $4.27/oz
Garnier Fructis · Leave-in
Curl Refresher Spray
#7 on the label · $0.94/oz
It's a 10 · Styler
It's a 10 Clear Miracle Gel
#7 on the label · $5.00/oz
See all 595 products in the library that list Sodium Hydroxide
Identity
What this entry is, and what our references call it.
Sodium Hydroxide
- CAS 1310-73-2
- PubChem 14798
- sodium hydroxide
For your hair?
Whether Sodium Hydroxide matters for your hair depends on your hair.
the 4th most-listed chelator or pH adjuster in our libraryWhat 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 is read from the ingredient lists in our library and from published references — the consultation is what turns it into a plan.
References
Sourced Backed by a manufacturer or regulatory source.
This ingredient
- Manufacturer or regulatory International Journal of Trichology — Gavazzoni Dias et al. (2014) on why the finished pH is what matters: alkaline conditions raise the fibre's negative surface charge, increase inter-fibre friction and open the cuticle scales, while acidic ones keep them flatter. · accessed 2026-08-30
- Manufacturer or regulatory PubChem — Compound identity: CID 14798, CAS 1310-73-2, HNaO · accessed 2026-08-28
How this page was made
- Every number above is counted from the ingredient lists in our own product library — 595 of 3889 researched products list this ingredient. Nothing on this page is written per ingredient.
- The dots are named levels read from an ingredient’s chemical class, charge, solubility, or where it sits on the labels we have — never a score.
- 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; where none is, the row is simply absent rather than filled in.
- This is cosmetic information, not medical advice, and nothing here diagnoses or treats a health condition.
- Entry last updated 2026-08-31. Product-page methodology: the product library.