effective vitamin c serum k beauty [SEP] i am always interested in trying new skincare products brands and innovations mizon is a well regarded south korean skincare brand vitamin c serum loses efficacy when it is exposed to oxygen mizun uses arbutin to lengthen the efficacy of the serumtopical vitamin c sometimes irritates my skin but i had no sensitivity to this it did go on easily with no greasiness or tacky feel it does feel like it tightens my skin and gives it a more even brighter tone