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
-counter dandruff or medicated shampoos. Active ingredients in these shampoos include salicylic acid, coal tar, zinc, resorcin, ketoconazole, or selenium. You have been prescribed the correct treatment by your dermatologist and you should use it as prescribed.