Iron Powder

Iron powder is an insoluble particulate used mainly as a colorant/pigment in cosmetics; while it is not a biochemical “active,” fine particles can cause mechanical irritation (grittiness, microabrasion) and provoke stinging when applied to compromised barriers (eczema, post-procedure). Clinically, insoluble metal/oxide pigments are generally low in irritancy at typical use levels, but in sensitized or inflamed skin the physical friction and potential for trace metal contaminants justify a mild score from a patient-safety standpoint. Safety Notes: In consumer skincare, iron powder is most often encountered as a minor colorant/optical modifier or as a trace component in mineral blends, with commercial INCI lists supporting use down to ~0.001–0.01% in leave-on products where only a small amount is needed for tone adjustment. The highest observed OTC levels are in specialty exfoliating/polishing products (typically rinse-off) or novelty “magnetic”/metallic effect masks where a perceptible particulate load is required, reaching ~1–5% while still maintaining spreadability, skin feel, and acceptable irritation risk. Above this, products tend to become cosmetically unacceptable (gritty/heavy) and are more likely to fall into non-skincare or professional-use categories, which are excluded here.