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Ingredient on hair labels

Propylene Glycol

TheWashDay editorial · Updated · From the EU ingredient register and the makers’ own labels · How we match names

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Propylene Glycol is on 22 of the 177 hair-product labels we compare, from 12 makers. Its uses in the EU ingredient register include humectant, fragrance and solvent. 2 of these labels name it among the first five ingredients.

See it on each label Products without it

What it is

In the register’s words: “Propylene Glycol is the aliphatic alcohol.”

EU register name (INCI)
PROPYLENE GLYCOL
CAS number
57-55-6
EC number
200-338-0

What the register lists it for

These are the uses the European Commission’s CosIng register lists for Propylene Glycol in any cosmetic, hair roles first. They say why a maker might add it, not what it does in one formula, and they aren’t a safety rating.

Humectant

Holds water in the product and on the surface it touches. Glycerin, honey and aloe are common humectants on curly-hair labels.

Register definition: “Retaining and/or preserving the moisture in a product during use.”

Fragrance

Gives the product its smell or covers an unpleasant one. A label may name each scent ingredient or group them as Fragrance (Parfum).

Register definition: “Imparting an odour or taste. Creating a perceivable pleasant smell and/or masking a bad smell.”

Solvent

Dissolves other ingredients. Water is the most common; some alcohols and glycols carry this role too.

Register definition: “Dissolving other components of cosmetics. Solvents are usually liquids (aqueous and nonaqueous).”

Viscosity controlling

Makes a product thicker or thinner, so a gel holds its shape or a shampoo pours. Gums, cellulose and some salts carry this role.

Register definition: “Increasing or decreasing the viscosity (thickness) of cosmetics.”

Skin humectant

Draws water into the top layers of skin. Glycerin-type ingredients carry it alongside the plain humectant role.

Register definition: “Increasing the water content of the top layers of the skin. Humectants are primarily hygroscopic agents drawing moisture from the surrounding air.”

Skin conditioning

A register role for ingredients that help dry or rough skin feel supple again.

Register definition: “Enhancing the appearance of dry and/or damaged skin by reducing flaking and restoring suppleness.”

Where it sits on each label

US labels list ingredients from most to least, except that those at 1% or less may follow in any order. A name near the top is a large part of the formula. A label doesn’t mark where the 1% point falls, so further down, the order says little about how much is in it.

Every label, product by product (22)

Each line runs from the first name on a label to the last; a dot is where this ingredient sits. Makers change formulas now and then; if the list on your bottle differs, go by your bottle.

Your next step

Find products without Propylene Glycol Check every name on your own label All ingredients on the labels we compare

Other humectant ingredients on these labels

Updated · The name, numbers and uses come from the European Commission’s CosIng entry (CC BY 4.0); we write the uses in US spelling and put the hair ones first. The labels are each maker’s own. The order rule is the FDA’s Cosmetics Labeling Guide. All our sources are on the Sources page.