Common Name(s): 1,2-propanediol,pdg,propane-1,2-diol

CAS Number: 57-55-6

DESCRIPTION

What It Does: Provides humectant hydration alongside solubilization of water-soluble actives and preservation boosting.

Why It's Used: Multi-function glycol for comprehensive formulation utility: hydration, solubilization, and preservation in a single cost-effective ingredient.

How It Works: Two hydroxyl groups provide water binding for humectant activity. propylene backbone provides solvent capacity for both polar and moderately non-polar actives. antimicrobial activity via membrane disruption enhancing preservative systems.

Typically Found In: Moisturizers,serums,toners,almost all aqueous formulations

TECHNICAL DETAILS

Primary Category: Functional ingredient – glycol humectant / solvent

Secondary Functions: Tewl reduction,skin plumping

Application Areas:

Typical Concentration Range: 1%–15%

SOURCING & ETHICS

Vegan Status: Yes – from propylene oxide (petrochemical) or bio-based (corn fermentation)

Halal Status: Yes

Source Notes: Synthetic or naturally derived. excellent aqueous solubility.

SKIN COMPATIBILITY

Irritancy Rating: 2/5 – low to moderate; potential sensitizer in sensitive individuals at high concentrations

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Non-irritating; suitable for all skin types.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Well-established safety profile. ewg score: 3. bio-based pg available from corn fermentation.

Works Well With: Ceramides,emollients,occlusives,glycerin,hyaluronic acid

Avoid Combining With: No significant incompatibilities

SCIENTIFIC NOTE

Propylene glycol's dual polarity (two hydroxyl groups + propylene hydrocarbon backbone) enables dissolution of ingredients spanning a wide hydrophilicity range – from highly polar actives (amino acids, glycerin) to moderately lipophilic actives (salicylic acid, retinol). this broad solubility range makes it uniquely versatile as a cosmetic solvent.

Last Verified: Cosing database,cir safety assessment

Primary Sources: 2026-03-12