Peg-120 Propylene Glycol Stearate: What Is It, Cosmetic Uses, Benefits & Side Effects

Curious about this ingredient? In this article we're explaining exactly what it is and why it's used within cosmetic formulations.
Updated on: July 1, 2025
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We verify all information on this page using publicly available nomenclature standards from The Personal Care Products Council (PCPC), the European Commission's CosIng database and documentation provided directly by ingredient manufacturers. Our analysis is based on technical data from these sources to ensure accuracy and reliability.

What Is Peg-120 Propylene Glycol Stearate?

Peg-120 Propylene Glycol Stearate is a large molecule created by attaching about 120 units of ethylene oxide to propylene glycol stearate, a fatty acid derived from stearic acid found in plant oils such as coconut or palm. The result is a wax-like substance that mixes easily with both oil and water.

This ingredient entered cosmetics in the late 20th century when formulators looked for gentler alternatives to traditional detergents. By tweaking the ratio of fatty acid to ethylene oxide they achieved a compound that cleans without stripping and helps oil droplets stay evenly spread in water-based formulas.

Manufacturing starts with stearic acid that is reacted with propylene glycol to make propylene glycol stearate. Ethylene oxide gas is then added in a controlled process that links the 120 repeating units, giving the final product its water-loving properties. Quality checks ensure the chain length and purity stay within cosmetic standards.

You will most often see Peg-120 Propylene Glycol Stearate in face cleansers, body washes, bubble baths, micellar waters, makeup removers, sheet masks and some lightweight moisturizers where a silky rinse-off feel is desired.

Peg-120 Propylene Glycol Stearate’s Cosmetic Benefits/Uses

This multitasker brings two main benefits to personal care formulas:

  • Cleansing: Its surfactant action loosens dirt, excess oil and makeup so they rinse away with water. Because it is derived from fatty acids it tends to be milder than sulfate-based cleansers leaving skin soft instead of tight.
  • Emulsifying: It helps oil and water blend smoothly, preventing separation in products like cream cleansers and two-phase makeup removers. A stable emulsion means consistent texture and performance from the first use to the last.

Who Can Use Peg-120 Propylene Glycol Stearate

Most skin types can use products containing Peg-120 Propylene Glycol Stearate. Its mild cleansing action suits normal, oily and combination skin while its fatty acid backbone helps it feel gentle enough for sensitive skin. Very dry or eczema-prone skin may prefer richer surfactants that deposit more lipids though most people in these groups still tolerate it well when it is blended with moisturising ingredients.

The ingredient is generally considered suitable for vegans and vegetarians because the stearic acid source in modern cosmetics is almost always plant derived, usually from coconut or palm oil, not tallow. Brands that are certified vegan typically confirm plant sourcing in their documentation.

Current safety data shows no specific risk for pregnant or breastfeeding women. That said this is not medical advice and anyone who is expecting or nursing should run their skincare routine past a healthcare professional to be safe.

Peg-120 Propylene Glycol Stearate does not make skin more sensitive to sunlight so it is not regarded as a photosensitiser. It is also fragrance free and non ionic which lowers the likelihood of interaction with active ingredients in the same formula.

Potential Side Effects/Adverse Reactions

Responses to topical Peg-120 Propylene Glycol Stearate vary from person to person. The effects listed below are possible yet unlikely when the ingredient is used at the concentrations found in finished cosmetics formulated by reputable manufacturers.

  • Mild skin irritation such as redness stinging or itching
  • Allergic contact dermatitis in individuals already sensitised to polyethylene glycols or propylene glycol
  • Temporary eye irritation if the product accidentally gets into the eyes
  • Dryness or tightness when used in very high concentrations or in formulas lacking added emollients

If any of these reactions occur stop using the product and consult a healthcare professional or dermatologist.

Comedogenic Rating

Rating: 1/5

The large polyethylene glycol portion keeps the molecule highly water soluble, preventing it from lingering on skin or mixing with sebum deep in pores. Studies on similar PEG esters report minimal pore clogging so its score stays near the bottom of the scale.

Generally suitable for acne prone skin at the low levels found in rinse off cleansers, micellar waters and light lotions.

Its quick rinse profile and use in formulas that are washed away after seconds add an extra margin of safety against breakouts.

Summary

Peg-120 Propylene Glycol Stearate works as a two in one helper: it cleans by surrounding oil and dirt so they wash away with water and it emulsifies by holding oil droplets in place inside water based products. The fatty acid tail provides slip while the long chain of ethylene oxide units binds to water letting the ingredient sit right at the oil water interface.

You will find it in plenty of mainstream cleansers and bubble baths yet brands rarely spotlight it so its popularity is more silent than splashy.

Decades of cosmetic use and safety reviews show it is low risk for most people, with only occasional mild irritation reported. Even so every skin is different so doing a small patch test when trying a new product containing this ingredient remains the safest move.

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