Seborrheic dermatitis is a common skin condition that causes flaky, dry, white to yellowish scales to form on
oily areas esp. under the nose or anywhere on face
. 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.