Psoriasis is a chronic (long-lasting) disease in which the immune system becomes overactive, causing skin cells to multiply too quickly. Patches of skin become scaly and inflamed, most often on the scalp, elbows, or knees, but other parts of the body can be affected as well.

Seborrheic dermatitis causes a rash of oily patches with yellow or white scales. The rash may look darker or lighter in people with brown or Black skin and redder in those with white skin. Seborrheic (seb-o-REE-ik) dermatitis is a common skin condition that mainly affects your scalp.

Eczema is a skin condition that causes dry and itchy patches of skin. It’s a common condition that isn’t contagious. Symptoms of eczema can flare up if you contact an irritant or an allergen. There are treatments available to help you manage symptoms, but there isn’t a cure.

Dandruff is a common condition that causes the skin on the scalp to flake. It isn’t contagious or serious. But it can be embarrassing and difficult to treat. Mild dandruff can be treated with a gentle daily shampoo. If that doesn’t work, a medicated shampoo may help.