At a glance
- CAS number
- 57-55-6
- INCI name
- Propylene Glycol
- Function
- humectant, solvent, preservative booster, emollient, viscosity decreasing agent
- Typical use level
- 1%–15%
- Solubility
- water
- Stable pH
- 3–11
CAS number and synonyms are sourced from PubChem. Function, usage levels, pH and compatibility are AI-assisted formulation guidance — verify against your supplier's technical data sheet and applicable regulations before use.
Also known as
propylene glycol 1,2-propanediol propane-1,2-diol 1,2-Propylene glycol 1,2-dihydroxypropane 2-Hydroxypropanol Isopropylene glycol Dowfrost Sirlene Methylethyl glycol Methylethylene glycol Monopropylene glycol
Compatibility
Works well with:
Glycerin Hyaluronic Acid Niacinamide Parabens Phenoxyethanol Carbomer Xanthan Gum Sodium PCA Urea Allantoin
Use caution with:
Oxidizing Agents Strong Acids Strong Bases
Propylene Glycol is broadly compatible with most cosmetic ingredients and is widely used as a carrier/solvent to help dissolve actives and boost preservative efficacy. It can cause irritation or sensitization at higher concentrations (above ~5-10%) in leave-on products, particularly in sensitive individuals. It is chemically incompatible with strong oxidizing agents, which can cause degradation.
Formulation notes
EU Cosmetics Regulation does not impose a specific leave-on concentration cap, but industry practice limits leave-on use to ≤15% to minimize sensitization risk; rinse-off products may use higher levels. Some consumers self-report sensitivity; patch testing recommended for sensitive skin formulations. Generally recognized as safe by CIR.
Related ingredients
- Butylene GlycolHumectant
- Pentylene GlycolHumectant
- PanthenolHumectant
- Caprylic/Capric TriglycerideEmollient
- Caprylyl GlycolPreservative
- CyclopentasiloxaneEmollient