Plaques are patches of skin that become inflamed and thickened; they are usually red in color and have a surface that is covered in silvery scales. Plaques on the scalp are usually covered by hair and not very visible to others, but the scale on top of the plaque can tend to flake and fall off in small pieces1. This can look much like regular dandruff, even though it is not the same thing. Both can cause itchiness and flaking, but dandruff is caused by a fungus and dandruff-like flaking due to psoriasis is caused by inflammation. People with scalp psoriasis can sometimes feel embarrassed or self-conscious about the dandruff-like flaking from the scalp plaques.
Just like other symptoms of psoriasis, dandruff-like flaking can come and go as psoriasis flares up for a period of time, and then symptoms go away for a while. Flare-ups of scalp psoriasis and dandruff-like flaking can have different causes for different people, but some common triggers are cold weather, dry air, and experiencing stress2.
What causes dandruff-like flaking in psoriasis?
Psoriasis plaques appear on patches of skin where too many new skin cells are being produced because the person’s immune system is overreacting and triggering inflammation3. Because there is not enough time for the older skin cells to die off and shed from the skin, the new cells push the older ones too quickly to the top layer of skin. This causes the silvery layer of scales on the top of a psoriasis plaque. Dandruff-like flaking occurs when the scales on top of plaques of the scalp flake off4.
How is dandruff-like flaking treated?
Several different medicated shampoos are available for treating scalp psoriasis. Generally, they are designed to be rubbed into the scalp, left for 5-10 minutes, and then reapplied. Shampoos made with coal tar are effective for many people with scalp plaques1. However, patients should be careful about using medicated shampoos exactly as directed, because using them too often can irritate the scalp and make symptoms worse. Remember to apply the shampoo very gently to the scalp, as rubbing or scratching too roughly can make symptoms worse2.
Scale softeners are topical treatments that can be applied directly to plaques on the scalp. By softening the scaly surface of the scalp plaques, it can reduce dandruff-like flaking and also allow other forms of topical treatments to penetrate the scalp plaques more deeply5. For example, coconut oil compound ointment combines coal tar, salicylic acid, and sulfur. It is left to work on the scalp for a period of time and then shampooed off.
The best way to reduce the amount of dandruff-like flaking is to treat the underlying psoriasis condition and reduce or eliminate the plaques. Anthralin, Dovonex (calcipotriene), Taclonex (capcipotriene), and Tazorac (tazarotene) are topical treatments for scalp psoriasis, as well as medicated scalp oils and foams that are left on the scalp for longer periods6. Phototherapy and laser treatments can also be effective in treating scalp psoriasis. Stronger systemic or biologic medications may be needed for more severe cases.