In several past NPF Advance articles, people have shared that they originally mistook their scalp psoriasis for dandruff. It is easy to understand why – dandruff is relatively common. We even see celebrity-endorsed anti-dandruff products in TV ads.
But what about when it isn’t dandruff, and those anti-dandruff products aren’t working? What else causes flaking on the scalp? It could be seborrheic dermatitis or possibly scalp psoriasis.
Technically, dandruff and seborrheic dermatitis have the same cause – a certain type of fungus – and together they affect around half of the population, mostly people from 15 to 50 years old. Dandruff is characterized by white flakes on the scalp and may include a feeling of dryness or tightness of the scalp. Seborrheic dermatitis, on the other hand, appears as yellow, oily flakes on the scalp and is frequently associated with itchiness and irritation, including occasional inflammation. 
Psoriasis, a chronic disease associated with inflammation throughout the body, affects 3% of the population, but over 50% of those people experience scalp psoriasis.  Scalp psoriasis is characterized by well-defined red, scaly plaques. On light-colored skin, the scales may have a silver-white appearance. On skin of color, the plaques may be darker and more purple or gray in color. Intense itchiness and burning sensations are common with scalp psoriasis, and plaques can extend from the scalp to the forehead, neck, or ears. In some cases, scalp psoriasis can cause temporary alopecia, or hair loss. 
Despite the differences in underlying causes, treatment for these conditions overlaps quite a lot. Both seborrheic dermatitis and scalp psoriasis involve hyperproliferation (uncontrolled growth) of the skin, causing it to build up and flake off. Keratolytic treatments, such as salicylic acid, can help break down the excess layers of skin. Anti-proliferative treatments, like coal tar, can slow skin growth and prevent this buildup in the first place.  Many of these treatments can be found in over-the-counter shampoos, several of which have received the NPF Seal of Recognition.