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

How does a doctor tell the difference between scalp psoriasis and seborrheic dermatitis of the scalp?

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Mayo Clinic dermatologist Lawrence Gibson, M.D., and colleagues answer select questions from readers.

Answer

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	Scalp psoriasis
	Seborrheic dermatitis of the scalp

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 symptoms, such as itchy, red, scaly skin. Fortunately, they also share some similar treatments, such as medicated shampoos. However, scalp psoriasis tends to be more resistant than does seborrheic dermatitis to these treatments.

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. So if you have scalp psoriasis, you may also have mild psoriasis on your elbows, knees, buttocks or fingers.

There is no single test to confirm a diagnosis of psoriasis or seborrheic dermatitis. A diagnosis is usually made with a visual examination of the affected skin. In rare cases, a skin biopsy may be needed to differentiate between the two disorders.

Scalp disorder	Signs and symptoms	Treatment
Scalp psoriasis	Red patches of skin covered with silvery scales Dry, cracked skin that may bleed Itching, burning or soreness	Over-the-counter medicated shampoos, such as those containing ketoconazole, tar, pyrithione zinc, selenium sulfide or salicylic acid Topical solutions, creams or ointments, such as tar products, corticosteroids or vitamin D analogues Light therapy
Seborrheic dermatitis of the scalp	Patchy scaling or thick crust on the scalp Yellow or white scales that may attach to the hair shaft Red, greasy skin covered with flaky white or yellow scales Small, reddish-brown bumps Itching or soreness Skin flakes or dandruff	Over-the-counter medicated shampoos, such as those containing ketoconazole, tar, pyrithione zinc, selenium sulfide or salicylic acid Topical solutions or creams such as hydrocortisone cream