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
- 1100
- of researched products
- 16%
- on the label, in our shampoos
- usually #20
- most common in
- Shampoo
- 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.
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, 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 ? |
|---|---|---|
Shampoo
473 products
|
secondary · #20 | |
Conditioner
185 products
|
secondary · #24 | |
Leave-in
89 products
|
secondary · #19 | |
Mask / treatment
78 products
|
secondary · #22 | |
Scalp treatment
62 products
|
secondary · #21 | |
Styler: gel
39 products
|
secondary · #17 | |
Styler: mousse
25 products
|
secondary · #21 | |
Styler: curl cream
24 products
|
secondary · #24 | |
Heat protectant
20 products
|
secondary · #18 | |
Styler: paste
19 products
|
secondary · #22 |
15 more product types
| Product type | How common | Typical position on label ? |
|---|---|---|
Finisher: serum
16 products
|
secondary · #24 | |
Styler: volumizer
14 products
|
secondary · #25 | |
Co-wash
13 products
|
secondary · #20 | |
Styler: smoothing cream
13 products
|
secondary · #22 | |
Styler: hairspray
6 products
|
secondary · #23 | |
Styler: refresh spray
5 products
|
secondary · #18 | |
Styler: texture spray
4 products
|
secondary · #16 | |
Dry shampoo
3 products
|
secondary · #17 | |
Styler: edge control
3 products
|
secondary · #24 | |
Styler: lotion
3 products
|
secondary · #22 | |
Finisher: shine spray
2 products
|
secondary · #14 | |
Finisher: anti frizz finish
1 product
|
secondary · #43 | |
Finisher: end oil
1 product
|
secondary · #40 | |
Finisher: oil
1 product
|
secondary · #22 | |
Relaxer
1 product
|
supporting · #7 |
| Product type | Products | Share of category | Median position | Earliest position | Band |
|---|---|---|---|---|---|
| Shampoo | 473 | 30% | 20 | 2 | secondary |
| Conditioner | 185 | 16% | 24 | 8 | secondary |
| Leave-in | 89 | 13% | 19 | 5 | secondary |
| Mask / treatment | 78 | 13% | 22 | 7 | secondary |
| Scalp treatment | 62 | 21% | 21 | 5 | secondary |
| Styler: gel | 39 | 15% | 17 | 3 | secondary |
| Styler: mousse | 25 | 12% | 21 | 11 | secondary |
| Styler: curl cream | 24 | 11% | 24 | 8 | secondary |
| Heat protectant | 20 | 10% | 18 | 7 | secondary |
| Styler: paste | 19 | 10% | 22 | 8 | secondary |
| Finisher: serum | 16 | 12% | 24 | 6 | secondary |
| Styler: volumizer | 14 | 10% | 25 | 11 | secondary |
| Co-wash | 13 | 13% | 20 | 10 | secondary |
| Styler: smoothing cream | 13 | 16% | 22 | 8 | secondary |
| Styler: hairspray | 6 | 2% | 23 | 9 | secondary |
| Styler: refresh spray | 5 | 14% | 18 | 6 | secondary |
| Styler: texture spray | 4 | 4% | 16 | 12 | secondary |
| Dry shampoo | 3 | 2% | 17 | 6 | secondary |
| Styler: edge control | 3 | 8% | 24 | 13 | secondary |
| Styler: lotion | 3 | 8% | 22 | 21 | secondary |
| Finisher: shine spray | 2 | 2% | 14 | 7 | secondary |
| Finisher: anti frizz finish | 1 | 3% | 43 | 43 | secondary |
| Finisher: end oil | 1 | 13% | 40 | 40 | secondary |
| Finisher: oil | 1 | 0% | 22 | 22 | secondary |
| Relaxer | 1 | 25% | 7 | 7 | supporting |
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 | 4 |
| 4-8 | Supporting | 50 |
| 9-15 | Secondary | 236 |
| 16-25 | Lower | 425 |
| 26+ | Trace | 385 |
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
Formulation guidance for specific hair conditions, limited to the label positions where it applies. It is not a conclusion about any finished product, or 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 seeing this ingredient tells you, what it does not, and the limits of our own method.
- 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, 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 pH adjuster, listed below the main ingredients in our shampoos
- it was on the printed ingredient list of every product we counted (we read labels, 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
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.
- Sodium Chloride · 407
- Ethylhexylglycerin · 364
- Cocamidopropyl Betaine · 354
- Benzyl Alcohol · 352
- Tocopherol · 347
- Guar Hydroxypropyltrimonium Chloride · 332
- Hexyl Cinnamal · 281
- Propylene Glycol · 273
- Behentrimonium Chloride · 271
- Caprylyl Glycol · 251
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, soften the strand, and clean and build foam.
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
ColorHarmony Purple Shampoo
#2 on the label · $1.00/oz
Leonor Greyl · Styler
Gel à l'Hibiscus
#3 on the label · $10.65/oz
Pura d'or · Shampoo
Apple Cider Vinegar Thin2Thick Clarifying and Detoxing Shampoo
#3 on the label · $1.00/oz
Pura d'or · Shampoo
Scalp Therapy Shampoo
#3 on the label · $1.25/oz
Everyone · Shampoo
Lavender Lullaby Kids 3in1 Soap
#5 on the label · $0.41/oz
Everyone · Shampoo
Tropical Coconut Kids 3in1 Soap
#5 on the label · $0.41/oz
It's a 10 · Leave-in
Miracle Blow Dry H2O Shield
#5 on the label · $8.00/oz
Kerastase · Shampoo
Genesis Bain Hydra-Fortifiant Shampoo
#5 on the label · $4.89/oz
Philip Kingsley · Scalp treatment
Flaky Scalp Mask
#5 on the label · $50.00/oz
Phyto · Scalp treatment
PHYTOCYANE Densifying Treatment for Progressive Hair Thinning - Men
#5 on the label · $708.33/oz
Pura d'or · Shampoo
Advanced Therapy Anti-Hair Thinning Shampoo
#5 on the label · $1.47/oz
Kerastase · Shampoo
Gloss Absolu Bain Hydra-Glaze Shampoo
#6 on the label · $4.78/oz
See all 1100 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 comes 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: 1100 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.
