Unlike many product lines, iS Clinical uses no ingredients that cause sun related reactions or sensitivities – in contrast to some other product lines. The Brightening Duo of Brightening Serum and Brightening Complex, contains high performing, botanically-based, antioxidant-rich ingredients that give superior protection to the skin all year round. iS Clinical always advises the application and reapplication of sunscreen daily. Hydroquinone-based products cannot be used for extended periods of time, as Hydroquinone generates free radicals and is cytotoxic. Brightening Serum and Brightening Complex do not have these limitations making them safe to use all year round.