The scalp is one of the most common and persistent areas affected by psoriasis (occurring in about 50 percent of all patients) and can be one of the most difficult places to treat. The scales on the scalp can be thick and silvery-white, and can stick together tightly to form dense crusts that can be very itchy. Picking at the scales and scratching the scalp can worsen the psoriasis.
Scalp psoriasis can be localized, involving only a few discrete areas or can affect the entire scalp. The lesions often appear behind the ears and along the hairline, but can spread beyond the hairline. If the ear canal is affected and accumulates enough scales, hearing may be impaired. Hair loss is uncommon because psoriasis does not affect the hair root, but in severe cases hair loss can occur. Hair usually regrows once the psoriasis is controlled.
Mild outbreaks of scalp psoriasis that remain hidden by the hair might not be noticed by an observer; however, severe forms can be extremely itchy and highly visible. Silvery-white scales (resembling dandruff) flake onto shoulders and collar, which can be embarrassing and emotionally stressful for the patient. Successful treatment is important to minimize the emotional stresses and physical discomforts.
Treatment of scalp psoriasis is challenging, but there are many therapies that can help. Sometimes, the best treatments are arrived at by trial and error, so it is important to be patient when treating and awaiting results. The following are some common forms of treatment.
Shampoos: Shampoos that contain active ingredients such as tar, salicylic acid, zinc pyrithione or selenium sulfide can be very helpful in reducing the scaling and thickness of scalp psoriasis. Recently, shampoos that contain steroids have been developed and can be quite helpful for patients.
Topical steroids: Steroid-containing scalp preparations can be very effective at reducing redness (inflammation) in psoriasis of the scalp. Steroids are usually prescribed either as a lotion, solution or foam for hair-bearing areas (creams and ointments are difficult to apply to the hair-bearing scalp, often causing the hair to become matted). Alcohol-based lotions can cause stinging, so a water-based lotion can be substituted (amcinonide).
Salicylic acid: Salicylic acid (keratolytic) is an ingredient found in certain over-the-counter shampoos. It is helpful in removing excessive scale, which in turn allows for the penetration of other medications (such as steroids) into the site of inflammation. Salicylic acid can be mixed in low concentrations in mineral oil or provided in combination with a topical steroid (betamethasone dipropionate/salicylic acid) or combined with tar in a shampoo.
Topical vitamin D analogues (calcipotriol): Topical calcipotriol scalp solution can be used alone or in combination with other topical treatments.
Anthralin: Anthralin can reduce the turnover of skin cells that cause the excessive buildup of scale, and reduce inflammation. As a result, it can be highly effective in treating scalp psoriasis. However, Anthralin can be messy and cause staining of the skin, blonde or gray hair, and clothing.
Anthralin can be applied directly to the skin for short periods (Short Contact Anthralin Therapy or SCAT) of 15 to 30 minutes. It should then be washed off to prevent irritation. Lower strengths of anthralin can be used and left on the skin for longer periods.
If your skin is tender and sore from psoriasis, anthralin might not be the best choice as it can cause irritation of the scalp.