Ingredient caution: mandelic acid/AHA might cause stinging, dryness, peeling, redness and increased sun sensitivity; niacinamide is usually gentle but might cause tingling or flushing in very reactive skin; tranexamic acid might cause tingling, dryness or redness in sensitive skin. Do a patch test before applying. First-time users should start 3–4 times a week, avoid using it with retinol or other exfoliating acids in the same routine, and apply sunscreen daily. 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. Avoid during pregnancy or breastfeeding unless your doctor approves. Stop use if irritation persists.