Ingredient caution: high-strength niacinamide might cause flushing, tingling or small bumps in reactive skin; azelaic acid might cause tingling, dryness or redness in sensitive skin; sulfur/zinc-based oil-control ingredients might feel drying or tight on already dry skin. Do a patch test before applying. First-time users should start 3–4 times a week and reduce frequency if redness or bumps appear. First-time users should start 3–4 times a week and pair with sunscreen, because pigmentation care works best with UV protection. Use a moisturiser and reduce frequency if the skin feels tight or flaky. Avoid during pregnancy or breastfeeding unless your doctor approves. Stop use if irritation persists.