HUMECTANT
Sodium PCA
- humectant
A moisture-binding ingredient that occurs naturally in hair and skin.
- products in our library
- 182
- of researched products
- 5%
- on the label, in our shampoos
- usually #20
- 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.
How strongly the class holds on to water.
The strongest binders are the ones the weather moves most.
| Property | Level | Out of |
|---|---|---|
| Buildup risk | Low | 1 of 5 |
| Rinse-out behaviour | Rinses clean | 5 of 5 |
| Water-binding | Strongest | 5 of 5 |
| Humidity sensitivity | Swings with the air | 5 of 5 |
What it does for a formula
What Sodium PCA does
The general function first, then how the role changes by product type where we have researched it.
Binds water and holds it against the hair rather than adding oil.
What a humectant does depends on the air around it as much as on the formula.
Water alone removes it, so it does not accumulate between washes.
Charge
Negatively charged, like the hair surface itself — so it is repelled rather than attracted, rinses away cleanly, and is the charge most detergents carry.
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
47 products
|
secondary · #20 | |
Leave-in
45 products
|
secondary · #22 | |
Mask / treatment
44 products
|
secondary · #26 | |
Conditioner
40 products
|
secondary · #29 | |
Heat protectant
18 products
|
secondary · #27 | |
Co-wash
14 products
|
secondary · #44 | |
Styler: smoothing cream
13 products
|
secondary · #21 | |
Scalp treatment
8 products
|
secondary · #14 | |
Styler: curl cream
6 products
|
secondary · #30 | |
Finisher: serum
4 products
|
secondary · #15 |
8 more product types
| Product type | How common | Typical position on label ? |
|---|---|---|
Styler: mousse
4 products
|
secondary · #19 | |
Styler: volumizer
4 products
|
secondary · #21 | |
Styler: hairspray
3 products
|
secondary · #18 | |
Styler: gel
2 products
|
secondary · #9 | |
Styler: paste
2 products
|
secondary · #20 | |
Finisher: anti frizz finish
1 product
|
secondary · #23 | |
Finisher: shine spray
1 product
|
secondary · #11 | |
Styler: texture spray
1 product
|
secondary · #15 |
| Product type | Products | Share of category | Median position | Earliest position | Band |
|---|---|---|---|---|---|
| Shampoo | 47 | 6% | 20 | 5 | secondary |
| Leave-in | 45 | 11% | 22 | 7 | secondary |
| Mask / treatment | 44 | 11% | 26 | 8 | secondary |
| Conditioner | 40 | 6% | 29 | 9 | secondary |
| Heat protectant | 18 | 13% | 27 | 9 | secondary |
| Co-wash | 14 | 14% | 44 | 21 | secondary |
| Styler: smoothing cream | 13 | 23% | 21 | 11 | secondary |
| Scalp treatment | 8 | 5% | 14 | 5 | secondary |
| Styler: curl cream | 6 | 6% | 30 | 16 | secondary |
| Finisher: serum | 4 | 5% | 15 | 4 | secondary |
| Styler: mousse | 4 | 3% | 19 | 13 | secondary |
| Styler: volumizer | 4 | 6% | 21 | 12 | secondary |
| Styler: hairspray | 3 | 3% | 18 | 17 | secondary |
| Styler: gel | 2 | 1% | 9 | 6 | secondary |
| Styler: paste | 2 | 2% | 20 | 18 | secondary |
| Finisher: anti frizz finish | 1 | 4% | 23 | 23 | secondary |
| Finisher: shine spray | 1 | 2% | 11 | 11 | secondary |
| Styler: texture spray | 1 | 2% | 15 | 15 | 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 | 0 |
| 4-8 | Supporting | 19 |
| 9-15 | Secondary | 66 |
| 16-25 | Lower | 93 |
| 26+ | Trace | 135 |
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.
High-porosity hair loses water fast; a humectant holds some of it in place for longer than the wash itself would.
Binds water into the outer layers of the strand, and water is what makes dry hair flexible again rather than brittle.
A humectant moves water in whichever direction the air allows: it holds moisture in humid conditions and can pull it back out of hair in very dry ones.
Read from this ingredient’s chemical class. Where we have researched the ingredient itself, that reading replaces the class one.
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.
- hydration that does not add oil
- hydration rather than oil
- a rinse-clean feel
- moisture that stays on coarse or porous hair
- 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 humectant, 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
- frizz in every climate — what it does depends on the air
- 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.
- Glycine · 79
- Arginine · 79
- Sodium Lactate · 78
- Serine · 74
- Alanine · 72
- Threonine · 72
- Proline · 70
- Tocopherol · 68
- Aspartic Acid · 67
- Behentrimonium Chloride · 67
The number beside a name is how many products in our library list both.
These ingredients tend to appear together to firm up damaged areas, hold on to water, 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.
Biolage · Finisher
Hydra Source Moisture Method Scalp & Hair Serum
#4 on the label · $13.25/oz
Goldwell · Conditioner
Color Extra Rich Brilliance Conditioner
#4 on the label · $2.15/oz
Act+Acre · Scalp treatment
Daily Hydro Scalp Serum with Hyaluronic Acid
#5 on the label · $24.00/oz
Goldwell · Conditioner
Dualsenses Blondes & Highlights Anti-yellow Conditioner
#5 on the label
Mixed Chicks · Shampoo
Shampoo for Kids
#5 on the label · $1.06/oz
Goldwell · Conditioner
Dualsenses Ultra Volume Bodifying Conditioner
#6 on the label · $2.15/oz
Productos LATINA · Styler
Liquid Gel Hydration
#6 on the label · $2.17/oz
Briogeo · Mask / treatment
Curl Charisma Rice Amino Avocado Hydrating Defining Mask
#7 on the label · $4.88/oz
Carol's Daughter · Leave-in
Black Vanilla Moisture & Shine Leave-In Conditioner
#7 on the label · $1.57/oz
Christophe Robin · Shampoo
Hydrating Shampoo with Aloe Vera
#7 on the label · $4.40/oz
Divi · Scalp treatment
Scalp Serum
#7 on the label · $47.53/oz
Paul Mitchell · Leave-in
Awapuhi Moisture Mist
#7 on the label · $1.76/oz
Identity
What this entry is, and what our references call it.
Sodium PCA
- CAS 54571-67-4
- PubChem 23666346
- pca
- sodium pca
- sodium pca (and) sodium lactate (and) arginine (and) aspartic acid (and) pca (and) glycine (and) alanine (and) serine (and) valine (and) proline (and) threonine (and) isoleucine (and) histidine (and) phenylalanine (and) water
For your hair?
Whether Sodium PCA matters for your hair depends on your hair.
the 5th most-listed humectant 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 PubChem — Compound identity: CID 23666346, CAS 54571-67-4, C5H6NNaO3 · accessed 2026-08-28
How this page was made
- Every number above is counted from the ingredient lists in our own product library — 182 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 2026-08-28. Product-page methodology: the product library.