Seborrheic Dermatitis...

Joseph Bark notes that "Redness and itching is actually seborrheic dermatitis, and it frequently occurs around the folds of the nose and the eyebrow areas, not just the scalp." Dry, thick, well-defined lesions consisting of large, silvery scales may be traced to the less common psoriasis of the scalp.

Seasonal changes, stress, and certain diseases seem to affect seborrheic dermatitis. The cold, dry air of fall and winter often triggers a flare-up. Emotional stress can worsen the condition as well. Simple dandruff does not cause hair loss.