What are the triggers?
Sometimes there is an underlying condition causing the itching and flaking. The most common is called sebhorroeic dermatitis, the other is psoriasis. However, many people just have dry scalp that itches and flakes, perhaps due to the hair products they use, or the frequency with which they wash their hair.
What are the symptoms and signs?
The typical ones are itchy scalp, which sheds flakes onto the shoulders, and which may also be visible in the hair. Sebhorroeic dermatitis may also have yellow crusts and an oily appearance to the scalp and hair. Psoriasis will show raised and red areas of scalp, that may extend across the hair line onto the neck or face.