Ingredient caution: niacinamide is usually gentle but might cause tingling or flushing in very reactive skin; cleansing surfactants might cause dryness, stinging or tightness if overused; 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. Start slowly if your skin is sensitive and avoid combining too many new actives at once. Use lukewarm water, do not scrub, and follow with moisturiser. Apply on slightly damp skin and follow with moisturiser if dryness occurs. Stop use if irritation persists.