What Is Peg-5 Glyceryl Isostearate?
Peg-5 Glyceryl Isostearate is a synthetic ingredient created by combining glycerin, isostearic acid and a small chain of polyethylene glycol units. Chemically it is an ester, meaning a fatty acid is bonded to a polyol backbone. The “5” in its name signals that the molecule has been reacted with an average of five units of ethylene oxide, giving it mild water-loving properties while the isostearic acid end remains oil-loving. This dual nature lets it bridge the gap between oil and water in cosmetic formulas.
The material traces its roots to the late twentieth century when formulators were searching for gentler, plant-derived alternatives to harsher surfactants. By esterifying glycerin from vegetable oils with branched isostearic acid, chemists achieved a soft, silky feel plus reliable emulsifying performance. Once the base ester is formed, it is carefully ethoxylated under controlled temperature and pressure, purified and tested for cosmetic use.
Thanks to its balance of moisturising lipid content and light, non-greasy finish, Peg-5 Glyceryl Isostearate shows up in a wide range of products: daily moisturisers, rich night creams, facial cleansers, sheet masks, anti-aging serums, sunscreens, light body lotions, makeup removers and even some hair conditioners where it adds slip and mildness.
Peg-5 Glyceryl Isostearate’s Cosmetic Benefits/Uses
Formulators reach for this ingredient because it improves both the texture and performance of a product in more than one way.
- Emollient – softens and smooths the skin by filling in microscopic gaps between surface cells, leaving a supple, conditioned feel without an oily residue
- Emulsifying – helps mix oil and water phases into a stable, uniform cream or lotion so the product stays homogenous during storage and glides on evenly during use
Who Can Use Peg-5 Glyceryl Isostearate
Peg-5 Glyceryl Isostearate is generally well tolerated by most skin types, including dry, normal and combination. Its light emollient feel makes it comfortable even for oily or acne-prone skin since it does not leave a greasy film. Sensitive skin usually handles it well because it is considered mild and non-sensitising, though anyone with a history of reactions to polyethylene glycol derivatives should be cautious.
The ingredient is produced from glycerin and plant-derived fatty acids that undergo a synthetic process free of animal by-products, so it is suitable for both vegetarians and vegans.
No research points to problems when the ingredient is used topically during pregnancy or while breastfeeding. This is not medical advice and anyone who is pregnant or nursing should run new skincare products past a doctor just to be safe.
Peg-5 Glyceryl Isostearate does not absorb UV light and is not known to raise the skin’s sensitivity to the sun. Normal daytime sun protection practices are still recommended.
Potential Side Effects/Adverse Reactions
Reactions to topical Peg-5 Glyceryl Isostearate depend on individual sensitivity. The effects listed below are possible yet uncommon when the ingredient is used at normal cosmetic levels.
- Redness or mild irritation
- Stinging on very compromised skin
- Contact allergy in people already sensitised to polyethylene glycol compounds
Discontinue use and seek medical advice if any of these reactions occur.
Comedogenic Rating
Rating: 1/5
This ester is partly water soluble and has a light, silky texture, so it rinses away more easily than heavier straight oils. Studies and anecdotal feedback rarely associate it with clogged pores, placing it near the non-comedogenic end of the scale.
Most people who are prone to acne or breakouts can use it without issues, provided the overall formula is also low in pore-clogging ingredients.
Keep in mind that very rich creams containing multiple heavy lipids can bump the real-world comedogenic potential of any single ingredient, including this one.
Summary
Peg-5 Glyceryl Isostearate serves as an emollient and an emulsifier. Its fatty acid tail softens the skin while the short PEG chain attracts water, letting it lock oil and water together so products stay smooth and stable.
The ingredient is a quiet staple rather than a superstar, showing up in plenty of moisturisers, cleansers and sunscreens because it delivers a pleasant feel at an affordable cost.
Regulatory reviews consider it low risk when used at cosmetic levels and adverse reactions are uncommon. Still, patch test any new product that contains it to be on the safe side.