Ingredient caution: retinol/retinoids might cause dryness, peeling, redness, purging and sun sensitivity; 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; 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. Retinol is not advised for pregnant or breastfeeding women unless approved by a doctor. First-time users should start 3–4 times a week at night, avoid layering with exfoliating acids, and use sunscreen daily. 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. Stop use if irritation persists.