SOLVENT
Propylene Glycol
- solvent
A small humectant and solvent that keeps formulas stable and helps active ingredients spread.
- products in our library
- 655
- of researched products
- 17%
- on the label, in our shampoos
- usually #17
- 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 fast it leaves after the product is applied.
What is still on the hair once it has evaporated.
| Property | Level | Out of |
|---|---|---|
| Buildup risk | Low | 1 of 5 |
| Rinse-out behaviour | Rinses clean | 5 of 5 |
| Drying speed | Steady | 2 of 5 |
| Residue | Minimal | 2 of 5 |
What it does for a formula
What Propylene Glycol does
The general function first, then how the role changes by product type where we have researched it.
What everything else is dissolved in before it reaches your hair.
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
Carries no charge, so it neither clings to hair nor is pushed away by it. Nonionic ingredients are the mild, pH-tolerant workhorses of a formula.
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
131 products
|
secondary · #17 | |
Conditioner
115 products
|
secondary · #15 | |
Leave-in
91 products
|
supporting · #7 | |
Mask / treatment
81 products
|
secondary · #14 | |
Styler: paste
37 products
|
supporting · #6 | |
Styler: mousse
35 products
|
supporting · #8 | |
Styler: gel
33 products
|
supporting · #7 | |
Heat protectant
29 products
|
secondary · #9 | |
Scalp treatment
18 products
|
secondary · #14 | |
Styler: curl cream
12 products
|
secondary · #11 |
13 more product types
| Product type | How common | Typical position on label ? |
|---|---|---|
Styler: volumizer
12 products
|
supporting · #6 | |
Finisher: serum
11 products
|
secondary · #12 | |
Finisher: shine spray
9 products
|
supporting · #5 | |
Co-wash
7 products
|
secondary · #20 | |
Styler: hairspray
7 products
|
secondary · #13 | |
Styler: smoothing cream
7 products
|
supporting · #7 | |
Styler: texture spray
7 products
|
supporting · #5 | |
Finisher: oil
5 products
|
secondary · #13 | |
Styler: edge control
4 products
|
supporting · #6 | |
Styler: refresh spray
2 products
|
leading · #3 | |
Finisher: anti frizz finish
1 product
|
leading · #2 | |
Finisher: end oil
1 product
|
supporting · #4 | |
Styler: lotion
1 product
|
secondary · #13 |
| Product type | Products | Share of category | Median position | Earliest position | Band |
|---|---|---|---|---|---|
| Shampoo | 131 | 16% | 17 | 3 | secondary |
| Conditioner | 115 | 16% | 15 | 2 | secondary |
| Leave-in | 91 | 21% | 7 | 2 | supporting |
| Mask / treatment | 81 | 21% | 14 | 1 | secondary |
| Styler: paste | 37 | 41% | 6 | 2 | supporting |
| Styler: mousse | 35 | 25% | 8 | 2 | supporting |
| Styler: gel | 33 | 21% | 7 | 2 | supporting |
| Heat protectant | 29 | 20% | 9 | 2 | secondary |
| Scalp treatment | 18 | 11% | 14 | 4 | secondary |
| Styler: curl cream | 12 | 11% | 11 | 2 | secondary |
| Styler: volumizer | 12 | 18% | 6 | 2 | supporting |
| Finisher: serum | 11 | 14% | 12 | 1 | secondary |
| Finisher: shine spray | 9 | 14% | 5 | 1 | supporting |
| Co-wash | 7 | 7% | 20 | 12 | secondary |
| Styler: hairspray | 7 | 7% | 13 | 2 | secondary |
| Styler: smoothing cream | 7 | 13% | 7 | 2 | supporting |
| Styler: texture spray | 7 | 12% | 5 | 2 | supporting |
| Finisher: oil | 5 | 3% | 13 | 2 | secondary |
| Styler: edge control | 4 | 25% | 6 | 3 | supporting |
| Styler: refresh spray | 2 | 15% | 3 | 2 | leading |
| Finisher: anti frizz finish | 1 | 4% | 2 | 2 | leading |
| Finisher: end oil | 1 | 11% | 4 | 4 | supporting |
| Styler: lotion | 1 | 8% | 13 | 13 | 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 | 126 |
| 4-8 | Supporting | 161 |
| 9-15 | Secondary | 172 |
| 16-25 | Lower | 199 |
| 26+ | Trace | 92 |
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.
Light and water-binding rather than oily, so it hydrates without contributing weight.
A small water-binding solvent. It holds moisture and helps the rest of the formula spread evenly over the strand.
A humectant follows the air: it holds water in humid conditions and can give it up in very dry ones. Climate decides what it does more than the label does.
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.
- a light, fast-drying formula
- hydration rather than oil
- a rinse-clean feel
- body without weight on fine 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 solvent, 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.
- Hexyl Cinnamal · 223
- Benzyl Alcohol · 218
- Behentrimonium Chloride · 207
- Citronellol · 177
- Cetrimonium Chloride · 173
- Disodium EDTA · 162
- Sodium Hydroxide · 159
- Isopropyl Alcohol · 158
- Cetyl Alcohol · 147
- Sodium Chloride · 145
The number beside a name is how many products in our library list both.
These ingredients tend to appear together to give it a scent, carry the formula and let it dry, and improve feel after rinsing.
Found in these products
The most prominent placements first. The badge is the position on that product’s own ingredient list.
Color Wow · Finisher
Pop & Lock Frizz Control & Glossing Serum
#1 on the label · $13.33/oz
Color Wow · Finisher
Pop & Lock High Gloss Finish
#1 on the label · $13.33/oz
Joico · Mask / treatment
Defy Damage In A Flash 7-Second Bond Builder
#1 on the label · $4.73/oz
One 'n Only · Finisher
Shiny Silver Ultra Shine Spray
#1 on the label · $2.50/oz
American Crew · Styler
Boost Powder
#2 on the label · $46.48/oz
amika · Heat protectant
Brooklyn Bombshell Blowout + Blow Dry Spray
#2 on the label · $4.78/oz
amika · Finisher
Brooklyn Bombshell Blowout Spray
#2 on the label · $4.78/oz
amika · Styler
Brooklyn Bombshell Blowout Spray - 6.7 oz
#2 on the label · $4.78/oz
amika · Finisher
Supernova Moisture & Shine Cream
#2 on the label · $9.62/oz
Aunt Jackie's · Styler
Baby Curls Moisture Rich Curling & Twisting Custard
#2 on the label · $0.73/oz
Aunt Jackie's · Styler
Curl La La Defining Curl Custard
#2 on the label · $0.47/oz
Aunt Jackie's · Leave-in
Knot Havin' It Leave-In Ultimate Detangling Moisturizer
#2 on the label · $0.91/oz
See all 655 products in the library that list Propylene Glycol
Identity
What this entry is, and what our references call it.
Propylene Glycol
- CAS 57-55-6
- PubChem 1030
- humectant
- propylene glycol
- propylene glycol (1,2-propanediol)
For your hair?
Whether Propylene Glycol matters for your hair depends on your hair.
the 3rd most-listed solvent or propellant 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 1030, CAS 57-55-6, C3H8O2 · accessed 2026-08-28
How this page was made
- Every number above is counted from the ingredient lists in our own product library — 655 of 3928 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.