Stearoxyether Hydroxypropyl Methylcellulose — INCI reference

What it is

Stearoxyether Hydroxypropyl Methylcellulose is a chemically modified cellulose polymer produced by reacting stearyl glycidyl ether with hydroxypropyl methylcellulose (HPMC). The reaction introduces a long-chain stearoxy group onto the cellulose backbone, giving the polymer both hydrophilic and lipophilic character. This amphiphilic nature allows it to function as an effective thickener in water-based clear gels and as a stabilizer in oil-in-water emulsions. It is used across a wide range of personal care formulations including serums, moisturizers, sunscreens, hair conditioners, and color cosmetics. In sunscreen products it helps build high-viscosity, transparent gel textures without clouding. It is considered a mild ingredient with no reported significant allergenicity or irritation concerns at typical use levels.

Safety & warnings

No significant safety concerns have been identified for this ingredient at typical cosmetic use levels. The GHS classification is listed as none found. No allergen or irritant designations are documented. As a large polymer molecule, skin penetration is negligible, limiting systemic exposure. The ingredient is not intended for fragrance or flavor use. As with other cellulose derivatives, no comedogenicity or sensitization data of concern have been reported.

Origin & sourcing

Derived from cellulose — the most abundant natural polymer, sourced from wood pulp or cotton. The base material, hydroxypropyl methylcellulose, is produced by treating cellulose with propylene oxide and methyl chloride. Further reaction with stearyl glycidyl ether introduces the stearoxy ether side chain, making the final ingredient semi-synthetic. The commercial trade form Sangelose 90 L is manufactured by Ikeda (Japan).

History

Hydroxypropyl methylcellulose has been used in pharmaceuticals and cosmetics since the mid-20th century. Stearoxy-modified HPMC variants were developed to extend HPMC performance to emulsion stabilization and amphiphilic gel systems, broadening its utility in modern prestige skincare. The ingredient is registered in the EU CosIng database (REF No. 56831) and appears in a variety of international cosmetic formulations.

Questions everyone asks

What does Stearoxyether Hydroxypropyl Methylcellulose do in sunscreens?

It acts primarily as a viscosity controlling agent, helping to build the thick, clear gel texture common in many Japanese and Korean sunscreen formulations. It also helps stabilize the emulsion, keeping ingredients evenly distributed throughout the product.

Is this ingredient natural or synthetic?

It is semi-synthetic. It starts from cellulose, a natural polymer found in plant cell walls, but is chemically modified with synthetic reagents (propylene oxide, methyl chloride, and stearyl glycidyl ether) to produce the final compound.

Is Stearoxyether Hydroxypropyl Methylcellulose safe for sensitive skin?

Available data indicate it is generally well tolerated. No significant allergenicity, irritation, or comedogenicity has been reported. It is used in formulations from mainstream brands at low concentrations, and its large molecular size limits skin penetration.

What is the trade name for this ingredient?

The best-known commercial form is Sangelose 90 L, manufactured by Ikeda and distributed by Nordmann. It is marketed as a water-soluble thickener for clear formulations and as an emulsion stabilizer, particularly suited to high-viscosity gel systems.