Propylene Glycol

PROH-puh-leen GLY-kol

Humectant, Solvent 7/10 Safety CG ApprovedControversial Synthetic Vegan

What Is Propylene Glycol?

Propylene Glycol is a synthetic diol (double alcohol) that serves as a humectant, solvent, and penetration enhancer in hair care products. It is a clear, slightly viscous liquid with a faintly sweet taste. While it has gotten a bad reputation due to its use in antifreeze, the cosmetic grade is completely different from industrial grade and is recognized as safe.

Source: Petroleum-derived (synthetic) or plant-derived (from vegetable glycerin)

Origin: Synthetic

Also known as: PG, 1,2-Propanediol, Methyl Ethyl Glycol, Propane-1,2-diol

What Does Propylene Glycol Do to Your Hair?

Propylene Glycol attracts and binds water to keep hair moisturized, similar to glycerin but with better penetration-enhancing properties. It helps other active ingredients absorb more effectively into the hair and scalp. It also acts as a solvent that keeps product formulations stable and evenly mixed.

Best For

All hair types, dry hair, products requiring enhanced ingredient delivery

Not Recommended For

Sensitive scalp (may cause irritation in some), eczema-prone individuals

Concentration Matters

1-50%

Hair Type Compatibility

1A Straight Fine
1B Straight Medium
1C Straight Coarse
2A Wavy Fine
2B Wavy Medium
2C Wavy Coarse
3A Curly Loose
3B Curly Tight
3C Curly Corkscrew
4A Coily S-Shaped
4B Coily Z-Shaped
4C Coily Tight

Method Compatibility

Curly Girl (CG) Method: Approved
CG Approved

Safety & Regulation

7/10
AvoidCautionSafe

Safe at cosmetic concentrations according to all major regulatory agencies. Can cause contact dermatitis in sensitive individuals (estimated 2-5% of the population). Cosmetic-grade PG is distinct from industrial antifreeze PG. The American Contact Dermatitis Society named it Allergen of the Year in 2018.

FDA Status: Generally Recognized As Safe

FDA classifies as GRAS for food use. Approved for cosmetic use without concentration restrictions. EU permits in cosmetics.

EWG Score: 3/10

HairAide Verdict

Propylene Glycol is a functional ingredient that is safe for most people despite its undeserved bad reputation. If you have a known sensitivity to it, plant-derived Propanediol is an excellent alternative. For everyone else, there is no need to avoid products containing PG — it actually helps other beneficial ingredients work better.

Products That Contain Propylene Glycol

Shampoos, conditioners, serums, styling products, hair colors

Alternatives to Propylene Glycol

If you want to avoid Propylene Glycol, look for products with these ingredients instead:

Glycerin, Butylene Glycol, Propanediol (plant-derived), Pentylene Glycol

Frequently Asked Questions

Is Propylene Glycol safe for hair?

Yes, Propylene Glycol has a safety rating of 7/10 and is generally considered safe for use in hair products. Safe at cosmetic concentrations according to all major regulatory agencies. Can cause contact dermatitis in sensitive individuals (estimated 2-5% of the population). Cosmetic-grade PG is distinct from industrial antifreeze PG. The American Contact Dermatitis Society named it Allergen of the Year in 2018.

Is Propylene Glycol bad for curly hair?

Propylene Glycol is CG-method approved and is generally considered safe for curly hair.

Is Propylene Glycol CG-method approved?

Yes, Propylene Glycol is approved for the Curly Girl method.

What can I use instead of Propylene Glycol?

Some alternatives to Propylene Glycol include: Glycerin, Butylene Glycol, Propanediol (plant-derived), Pentylene Glycol

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