Seborrheic Dermatitis

A 35-year-old man reports itching, redness, and scaling in his scalp, eyebrows, and external auditory canal. He has tried several over-the-counter dandruff shampoos, with only temporary relief, and is increasingly embarrassed by this problem. Physical examination reveals greasy scaling on the scalp and erythema with yellowish scales in the nasolabial creases. How should his case be managed?