Brightening Serum can be used morning and evening, and is advised if hyperpigmentation is the primary concern. If the concern is minor, then the product can be used in either morning or evening. Whichever method is chosen, consistency is key, as hyperpigmentation can be challenging and time consuming to treat. Additionally, a full iS Clinical regimen is imperative – including cleansing and hydrating, morning and evening, and diligence with SPF application throughout the day.