It is really important that Ultrasun is applied first to clean, dry skin before another moisturising or beauty product, to allow Ultrasun to fully bind with your skin. As the Ultrasun products are absorbed into the stratum corneum (the top layer of your skin) they don't block the pores and won't block your other skin care products being absorbed into the skin. However other skincare products that are not non-comedogenic, contain oils and silcones may prevent Ultrasun from being fully absorbed and therefore protection levels.