http://meandmymastcells.com/category/nutrition/vitamins/ Well, i have been taking high doses of vitamin c for my mast cell problems because I know it is a mast cell stabilizer. Apparently in high amounts it becomes the opposite. Which may explain why my palms itch after taking high doses. This article says if you take 1g (1,000mg) split it throughout the day not all at once. *edited * I don't believe it's the vitamin c making my hands itch, but if it is it may be an additive.