Ingredient caution: vitamin C/ascorbic derivatives might cause tingling, redness or irritation in sensitive skin; niacinamide is usually gentle but might cause tingling or flushing in very reactive skin; fragrance, essential oils or fragrance allergens might trigger redness, itching or allergic irritation; rich oils, butters or occlusive emollients might feel heavy or clog pores in acne-prone/oily skin. Do a patch test before applying. First-time users should start 3–4 times a week and avoid layering with strong exfoliating acids if the skin stings. Start slowly if your skin is sensitive and avoid combining too many new actives at once. Avoid this product if you have fragrance allergy, eczema-prone skin or a damaged barrier. Use a small amount first and avoid applying on active acne if it feels greasy. Stop use if irritation persists.