Scalp Psoriasis Vs. Seborrheic Dermatitis: What’s The Difference?

When your scalp will not stop itching, it is time to take a closer look underneath your hair. Two common red, itchy rashes on the scalp are scalp psoriasis and seborrheic dermatitis.

What does each condition look like

Both are chronic inflammatory disorders that appear in people of all races. Treatments are similar but not exactly the same. So you need to know which disorder you have.

What does psoriasis look like?

• Well-defined, abnormally red, thickened patches of skin
• Flakes and silvery scales, often shed as dandruff
• Alopecia in some people, in whom hair loss causes bald spots
• Patches that may extend beyond the hairline or appear on other parts of the body

What does seborrheic dermatitis look like?

• Greasy-looking patches of skin
• Yellowish to white scales that may flake off as dandruff or attach to the hair shaft
• Patches that may form on parts of the body where the skin is oily

What are the other symptoms of psoriasis?

Psoriasis increases your risk of developing other serious health conditions:

• Cardiovascular disease, such as heart attack and stroke
• Certain types of cancer, such as lymphoma and nonmelanoma skin cancer
• Inflammatory bowel disease, such as Crohn's disease or ulcerative colitis
• Inflammatory eye disease
• Kidney disease
• Mood disorders, such as depression
• Metabolic syndrome, a cluster of conditions that include heart disease, abdominal obesity, high blood sugar, and high blood pressure
• Nonalcoholic fatty liver disease
• Obesity
• Osteoporosis
• Type 2 diabetes

Types of scalp psoriasis and seborrheic dermatitis

Scalp psoriasis may be very mild, with slight, fine scales. Or it can be very severe with thick, crusted plaques that cover the whole scalp.

If seborrheic dermatitis develops when you are a teenager or an adult, the condition can come and go for the rest of your life. Many babies get a type of seborrheic dermatitis called cradle cap. Cradle cap usually goes away forever within a few months.

Who do these conditions affect?

Men and women develop psoriasis at equal rates. Although psoriasis can occur at any age, it often develops between 15 and 35 years old. About 10 to 15 percent of people with psoriasis get it before they are 10 years old. Psoriasis is rare in infants.

Seborrheic dermatitis occurs a little more often in men than in women. People can develop seborrheic dermatitis at any age, but it is most common in adults between 30 and 60 years old and infants younger than 3 months. 9-10

What are the causes of scalp psoriasis and seborrheic dermatitis?

Neither scalp psoriasis nor seborrheic dermatitis is contagious. You cannot catch them from other people. Doctors think that factors work together to cause them.

Stress is a common trigger for both diseases. Discomfort from itching and embarrassment at the appearance of the diseases cause additional stress.

Psoriasis: Genetics play a role in psoriasis. About one in three people with psoriasis have a family member with the disease. If one parent has psoriasis, a child has about a 10 percent chance of getting it. If both parents have the disease, a child has about a 50 percent chance of getting it.

An overactive immune system contributes to psoriasis. An infection – strep throat, earache, bronchitis, tonsillitis, or a respiratory infection – may be followed two to six weeks later by the onset of psoriasis or a flare-up of the disease. Psoriasis sometimes develops in areas of skin that have been injured.

Seborrheic dermatitis: In spite of its appearance, the disease is not caused by poor personal hygiene. Scientists have found 11 gene mutations or protein deficiencies related to seborrheic dermatitis. The disease often first appears around puberty, indicating a link to changing hormones.

Among other causes may be a yeast or fungus that normally lives on human skin, a cold and dry climate, and harsh chemicals and soaps.

Some medical conditions increase your risk for seborrheic dermatitis.

• Those that affect the immune system, such as HIV/AIDS and psoriasis. About 85 percent of people infected with HIV develop seborrheic dermatitis.
• Those that affect the nervous system, such as Parkinson’s disease and epilepsy
• Others that affect the skin, such as acne and rosacea
• Mental health issues, such as depression and eating disorders
• Recovering from stroke or heart attack
• Alcoholism
• Some medications, such as interferon, lithium, and psoralen, also increase your risk.

How are these conditions diagnosed?

To help with diagnosis, your dermatologist – skin specialist – examines your skin and asks about your symptoms and your medical and family history. The doctor may take a sample of your skin – biopsy – and examine it under a microscope.

If seborrheic dermatitis is suspected, the doctor may scrape a bit of skin and mix it with a chemical before looking at it under a microscope to find out if there is a fungus infection.

How are these conditions treated

Scalp psoriasis and seborrheic dermatitis have some similar treatments, including medicated shampoos and topical treatments. You should closely follow your doctor’s directions to reduce or avoid side effects.

Scalp psoriasis: It can take time to find a good treatment because people respond differently to treatments. Your doctor may combine and rotate treatments to avoid side effects or because treatments sometimes become less effective over time.

Clobestasol propionate shampoo is safe and effective for both initial treatment and maintenance therapy. It has replaced some older shampoos.

Soaking your scalp in warm (not hot) water or applying oils, lotions, creams, or ointments to your damp scalp can help soften plaques. Then comb your scalp gently in light circular motions by holding your comb almost flat against your scalp to remove softened plaques. That will make it easier for topical treatments to penetrate your skin.

Corticosteroids are the most commonly prescribed topical treatments, available as creams, lotions, ointments, oils, gels, foams, solutions, and sprays. Other topical treatments use clobestasol propionate or vitamin A or D derivatives.

If your scalp psoriasis does not respond to other treatments or if it is severe, your doctor may prescribe an oral medication, such as apremilast, etanercept, methotrexate, acitretin, or cyclosporine. If you have not responded to other treatments or if you had bad side effects, your doctor may prescribe biologic drugs. Given by injection or by IV infusion, biologics block T-cells or specific proteins in the immune system.

Seborrheic dermatitis: Your treatment will focus on loosening scale, reducing inflammation and swelling, and relieving the itch.

Alternating between your regular shampoo and a medicated shampoo may relieve mild symptoms. Shampoos include ketoconazole, ciclopirox, selenium sulfide, and zinc pyrithione. For mild symptoms, your doctor may prescribe a topical antifungal cream, gel, or foam, such as ketoconazole or ciclopirox.

For more severe symptoms, your doctor may prescribe a topical corticosteroid or a topical calcineurin inhibitor, such as tacrolimus or pimecrolimus. If you have very severe symptoms, your doctor may prescribe an oral antifungal drug.