Illite is context-dependent for seborrheic dermatitis. It can absorb oil and add a smooth, matte feel, but that same absorbency may feel drying when skin is already flaky, tight or inflamed.

A cosmetic safety assessment supports the covered uses of Illite, while loose or sprayable powder formats need separate inhalation consideration. There is no direct human seb derm or ingredient-specific Malassezia evidence. In a rinse-off mask or cleanser, watch for tightness after use; avoid breathing loose powder and stop if the product repeatedly increases stinging or scaling.