Dandruff is a common condition causing the skin on the scalp to flake. Although it isn’t contagious, dandruff can be embarrassing and difficult to treat. Signs of dandruff include itchy scalp and skin flakes that can appear on the scalp, along the hair shaft, and on the shoulders. Dandruff tends to flare up in cold, dry seasons. Seborrheic dermatitis is a severe form of dandruff, where more fungus is present on the scalp where flaking and redness are found.