✦ Potent humectant that draws and binds moisture into skin and hair for lasting hydration
✦ Effective multi-purpose solvent that dissolves fragrances, extracts, and water-soluble actives
✦ Enhances penetration of active ingredients through the stratum corneum
✦ Acts as a preservative booster, extending product shelf life and improving microbial resistance
✦ Compatible with both oil-in-water and water-in-oil emulsion systems across a broad pH range
✦ Widely used across skincare, haircare, soap, and functional cosmetic applications
✦ Synthetically derived, vegan, and free from animal by-products

Propylene Glycol (PG) is a synthetic, water-miscible diol belonging to the alcohol family, chemically identified as 1,2-propanediol. It has been a staple of cosmetic, pharmaceutical, and food manufacturing for decades, valued for its unique ability to perform multiple formulation roles simultaneously. Its history in cosmetics dates to the mid-20th century, when it quickly became a standard ingredient across every major product category from skincare to haircare and beyond.

What makes Propylene Glycol particularly valuable to cosmetic formulators is its multifunctionality within a single ingredient. As a humectant, it binds water molecules and draws atmospheric moisture into the skin, improving hydration levels measurably. As a solvent, it creates homogenous dispersions of actives and fragrance materials throughout the formula. Its preservative-boosting capacity also allows formulators to reduce the concentration of primary preservatives without compromising microbial safety, resulting in better-tolerated finished products.

Bio Shop Pakistan supplies cosmetic-grade Propylene Glycol suitable for DIY beauty formulators, soap makers, perfumers, and professional cosmetic manufacturers seeking a reliable humectant and solvent base.

INCI Name : Propylene Glycol
Chemical Name : 1,2-Propanediol
CAS Number : 57-55-6
Molecular Formula : C3H8O2
Appearance : Clear, colorless, viscous liquid
Odor : Practically odorless with a faint sweet note
pH (1% solution) : 6.5 – 7.5
Solubility : Miscible with water, ethanol, and acetone; not miscible with fixed oils
Specific Gravity : 1.035 – 1.040 at 20°C
Flash Point : 99°C (210°F)
HLB Value : Not Applicable
Recommended Use Level : 1 – 15% in standard cosmetic formulations; up to 30% in specialized applications
Type : Humectant, Solvent, Penetration Enhancer, Preservative Booster
Shelf Life : 2 years when stored in a sealed container away from heat and light

Skincare (Creams, Serums, Lotions) ★★★★★
Propylene Glycol is a staple across all leave-on skincare categories, delivering reliable humectancy and solvent action at 2–5%. Add it to the water phase during formulation and adjust concentration based on skin type sensitivity.

Haircare (Shampoo, Conditioner, Masks) ★★★★☆
PG improves spreadability of conditioning agents and enhances moisture retention in the hair shaft. Use at 1–3% in shampoos and up to 5% in conditioners and deep treatment masks.

Soap Making (Cold Process, Melt and Pour) ★★★☆☆
PG is suited for melt and pour soap bases where it functions as a humectant and clarity agent, but it is not a standard cold process ingredient. Limit use to M&P applications where transparent or moisturizing bars are the goal.

Body Care (Scrubs, Butters, Balms) ★★★★☆
Performs well in body lotions and emollient balms as a hydrating and penetration-enhancing agent. Use at 2–5% for a smooth, non-tacky finish that aids absorption of heavier oils and butters.

Functional Cosmetics (Deodorants, Sunscreen, Baby Care) ★★★★☆
PG is widely used in deodorant sticks, roll-ons, and sunscreens as a reliable solvent for actives and a humectant. Reduce to a maximum of 1–2% in baby care products and always patch test on sensitive or pediatric skin.

In my formulation practice, Propylene Glycol is one of the first ingredients I reach for when I need simultaneous humectancy and solvent performance without disrupting emulsion stability. I add it directly to the water phase in both hot and cold process emulsions and it performs consistently at 3–5% across formulation types. For leave-on products intended for sensitive skin, I keep it at or below 2% and always pair it with glycerin to balance moisture delivery and reduce any potential for irritation.

ADVANCED TIP: To build a cost-effective broad-spectrum preservation system, combine Propylene Glycol at 4–5% with phenoxyethanol at 0.8% and ethylhexylglycerin at 0.3%. This combination leverages PG's ability to disrupt microbial cell membranes synergistically with phenoxyethanol's cellular toxicity and ethylhexylglycerin's surfactant-like antimicrobial action. The result is a preservation system that outperforms phenoxyethanol alone at a lower total preservative load, which translates directly to better skin tolerance and cleaner label positioning.

Normal Skin : ★★★★★ — Performs excellently as a humectant and solvent without congestion or sensitivity concerns.
Dry Skin : ★★★★★ — Draws and retains atmospheric moisture effectively, reducing tightness and improving skin feel.
Oily Skin : ★★★☆☆ — Tolerated at low concentrations of 1–2%, but higher levels may feel unnecessarily heavy on oily skin.
Combination : ★★★★☆ — Works well at moderate concentrations, supporting dry zones while remaining light enough for oily areas.
Sensitive Skin : ★★★☆☆ — May cause contact dermatitis or irritation in susceptible individuals; patch test strongly advised.
Mature Skin : ★★★★★ — Supports moisture retention in aging skin and improves penetration of actives into thinning epidermis.
Acne-Prone : ★★★☆☆ — Generally non-comedogenic but may trigger reactions in some acne-prone individuals; limit to 1–2% maximum.

CONCEPT 1: Hydrating Facial Serum
Usage Level : 5%
Key Ingredients: Hyaluronic Acid, Niacinamide, Panthenol, Aloe Vera Juice
Result : A lightweight, fast-absorbing serum that delivers layered hydration, improves skin tone, and supports barrier function.

CONCEPT 2: Moisturizing Body Lotion
Usage Level : 3%
Key Ingredients: Glycerin, Emulsifying Wax NF, Sweet Almond Oil, Vitamin E (Tocopherol)
Result : A smooth, non-greasy lotion that hydrates effectively and absorbs cleanly without leaving a sticky residue.

CONCEPT 3: Alcohol-Free Facial Toner
Usage Level : 4%
Key Ingredients: Rose Hydrosol, Allantoin, Sodium PCA, Witch Hazel Extract
Result : A refreshing hydrating toner that soothes and balances skin while improving absorption of subsequent serum layers.

INCI Declared : Yes — must appear on all finished cosmetic product labels
EU Cosmetics Reg : Permitted — not listed in Annex II, III, or V as a restricted or prohibited substance at standard cosmetic use levels
Rinse-Off Limit : No established restriction at typical cosmetic use levels
Leave-On Limit : No established restriction; CIR Expert Panel deems safe up to 50%, though typical cosmetic use is 1–15%
Allergen Alert : Yes — documented contact sensitizer in susceptible individuals, more common at concentrations above 5% in leave-on products
Skin Safety : Safe at recommended levels; patch test advised for sensitive skin types
Eye Area Use : Use with caution — limit to 1–2% maximum in eye area leave-on formulations
Ingestion : Not for internal use
Pregnancy Use : Consult physician before use in high-concentration topical applications during pregnancy
Child Safety : Use diluted at a maximum of 1–2% in products intended for children under 3 years
Ventilation : Not required under normal handling conditions
Storage : Cool, dry place away from direct heat, sunlight, and open flame; seal tightly after use
Container : HDPE or glass preferred — avoid prolonged storage in reactive metal containers

⚠️ Warning: Propylene Glycol has a documented potential to cause contact dermatitis and skin sensitization in susceptible individuals, particularly in leave-on formulations above 2–5%. Always conduct a patch test before inclusion in sensitive skin or pediatric formulations. Individuals with known PG sensitivity should avoid products containing this ingredient.

Working pH Range : 3 – 10
Heat Stability : Stable up to 160°C; suitable for both hot and cold process formulation
Freeze-Thaw Stable : Yes
Emulsion Type : Both (O/W and W/O)
Emulsification Phase: Either — add to water phase in hot process or dissolve actives in PG before cold blending
Compatible With : Humectants (glycerin, sorbitol, sodium PCA), preservatives (phenoxyethanol, ethylhexylglycerin), water-soluble actives, botanical extracts, fragrances and essential oils
Incompatible With : Strong oxidizing agents; excessive concentrations of anionic surfactants may reduce overall formula mildness
Oxidation Risk : Low — no antioxidant required under standard storage and formulation conditions
Discoloration Risk : None under standard storage temperatures and normal formulation conditions
Formulation Notes : Always add to the water phase before emulsification. When using PG as a solvent for actives or fragrances, pre-dissolve the active ingredient in PG before incorporating into the bulk formula for even distribution.

Q: What is Propylene Glycol used for in cosmetics?
A: Propylene Glycol is used primarily as a humectant, solvent, and preservative booster. It attracts and retains moisture in the skin, dissolves actives and fragrances, and extends product shelf life by enhancing microbial resistance.

Q: Is Propylene Glycol safe for daily use on skin?
A: At recommended concentrations of 1–5%, Propylene Glycol is considered safe for daily topical use by major regulatory bodies including the EU and US FDA. Individuals with sensitive skin or a known PG sensitivity should perform a patch test before regular use.

Q: At what percentage should I use Propylene Glycol in a face serum?
A: For a leave-on facial serum, 2–5% is the recommended range. Use at the lower end for sensitive or reactive skin types and up to 5% for normal to dry skin where enhanced humectancy is the primary goal.

Q: Can Propylene Glycol cause skin irritation?
A: Yes, it can cause contact dermatitis or irritation in sensitive individuals, particularly in leave-on formulations above 5%. Rinse-off products are generally better tolerated at slightly higher concentrations due to reduced exposure time.

Q: How does Propylene Glycol compare to Glycerin as a humectant?
A: Both are effective humectants but differ in texture and skin feel. Glycerin is thicker and stickier, providing a richer moisture sensation, while PG is thinner and absorbs more cleanly, making it preferred in lightweight serums and toners. PG also offers stronger solvent and preservative-boosting properties, which Glycerin does not. Many professional formulators combine both for balanced hydration and optimized texture.