Dandruff is a condition where the scalp exfoliates excessively producing visible white flakes on the hair and onto shoulders. Dandruff may also be associated with itch.
Lack of washing the hair can bring about dandruff.
There are a number of skin conditions that can produce dandruff. The most common is seborrheic dermatitis. It is an inflammatory skin ailment that present with flakiness and redness either or a combination on the scalp, eyebrows, ear canals, forehead and in the folds of skin that extend from nostril to commissure of the lips. The cause is unknown and treatment is life long.
There are other inflammatory diseases that produce excessive scaling such as psoriasis, fungal infection of the scalp and eczema.
Treatment depends on the cause. If its seborrheic dermatitis or eczema, it will require corticosteroid creams to reduce the inflammation. If the cause is fungal, requires antifungal creams.
Best to consult a doctor if the dandruff persist or worsens.