Hydrogenated Styrene/Methylstyrene/Indene Copolymer is a synthetic hydrocarbon resin used in cosmetics primarily to form a smooth, glossy film and to modify viscosity, particularly in lip products, sunscreens, and color cosmetics. It improves spreadability, shine, and wear, and helps suspend pigments.
| Reported effect | How often | Notes |
|---|---|---|
| Irritant contact dermatitis | Rare | Mild redness or irritation possible in sensitive individuals; generally considered low irritation potential. |
| Allergic contact dermatitis | Very rare | Sensitization is uncommon for inert hydrogenated hydrocarbon resins; few documented cases. |
| Comedogenicity / acneiform reactions | Rare | Occlusive film-forming nature may theoretically contribute to clogged pores in acne-prone users, though data are limited. |
Frequencies reflect typical cosmetic use reported in the literature, not a guarantee for your skin.