An itchy scalp can start as a minor irritation and quickly become difficult to ignore. While many people immediately assume dandruff is responsible, itching can have several different causes. Seborrheic dermatitis is a common one and may produce white or yellowish flakes, oily areas, redness, and persistent irritation. A dry scalp can also itch and flake, especially during colder weather or periods of low humidity.

But dandruff and dryness aren’t the only possibilities. Scalp psoriasis may produce thicker, well-defined scaly patches, while eczema can cause dry, inflamed and intensely itchy skin. Sometimes the problem begins shortly after changing shampoo, hair dye, conditioner, or another styling product. That can point toward irritation or contact dermatitis. And when itching appears suddenly or refuses to disappear, there are several other possibilities worth checking before assuming it’s ordinary dandruff.