Non-Flushing Vitamin B3 VeganNon-GMO Gluten Free Premium Dietary Supplement GMP Manufacturing Quality Assured Independent Testing Discussion: Niacin No-Flush is inositol hexanicotinate, an ester of niacin (vitamin B3). Regular niacin can cause unpleasant side effects such as itchy, burning skin - the niacin "flush". Inositol hexanicotinate has not been associated with the niacin "flush".