Ingredient caution: PHA, glycolic acid/AHA, salicylic acid/BHA might cause stinging, dryness, peeling, redness and increased sun sensitivity; 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; 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. 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. Avoid this product if you have fragrance allergy, eczema-prone skin or a damaged barrier. Apply on slightly damp skin and follow with moisturiser if dryness occurs. Stop use if irritation persists.