Ingredient caution: niacinamide is usually gentle but might cause tingling or flushing in very reactive skin; alpha arbutin, azelaic acid, tranexamic acid might cause tingling, dryness or redness in sensitive skin; humectants such as hyaluronic acid/glycerin are usually gentle but might feel sticky or tight if not sealed with moisturiser. Do a patch test before applying. Start slowly if your skin is sensitive and avoid combining too many new actives at once. First-time users should start 3–4 times a week and pair with sunscreen, because pigmentation care works best with UV protection. Apply on slightly damp skin and follow with moisturiser if dryness occurs. Avoid during pregnancy or breastfeeding unless your doctor approves. Stop use if irritation persists.