Scalp psoriasis vs. seborrheic dermatitis: What's the difference?

Scalp psoriasis and seborrheic dermatitis of the scalp can be difficult to differentiate. Both are common conditions that affect the scalp. In addition, they share similar signs and symptoms, such as itchy, red, scaly skin.

Most often, the scales of psoriasis are thicker and somewhat drier in appearance than are the scales of seborrheic dermatitis. In addition, psoriasis usually affects more than one area of the body. If you have scalp psoriasis, you may also have mild psoriasis on your elbows, knees, hands or feet or may notice subtle nail changes.

No single test confirms a diagnosis of psoriasis or seborrheic dermatitis. Your doctor usually makes a diagnosis with a visual examination of the affected skin. Fortunately, scalp psoriasis and seborrheic dermatitis of the scalp share some similar treatments, including:

• Over-the-counter medicated shampoos, such as those containing ketoconazole, tar or salicylic acid
• Ointment, gel or foam preparations, such as those containing tar products, corticosteroids or vitamin D analogues
• Mineral oil or an oil-based preparation applied to the scalp at night — and covered with a shower cap — to loosen scales and reduce inflammation

Scalp psoriasis is often persistent and more difficult to treat than seborrheic dermatitis. For stubborn cases of scalp psoriasis, your doctor may prescribe oral medications, such as methotrexate or cyclosporine, or combine stronger medications with medicated creams and ointments.