From the symptoms this problem of dry itchy scalp can be due to dandruff or seborrheic dermatitis
. You can treat flaking and dryness with over-the-counter dandruff or medicated shampoos. Shampoo the hair vigorously and frequently (preferably daily). Active ingredients in these shampoos include salicylic acid, coal tar, zinc, resorcin, ketoconazole, or selenium. But if your hair is colored, don't use products with selenium sulfide or sulfur.