Several medical conditions can present as dandruff. It is therefore best to get a medical opinion.
Dandruff is a condition where the scalp exfoliates excessively, producing visible white flakes on the hair which drift onto shoulders. Dandruff may also be associated with itchiness of the scalp.
Lack of washing the hair can also 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 on the scalp, eyebrows, ear canals, forehead, or 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 it is seborrheic dermatitis or eczema, it will require corticosteroid creams to reduce the inflammation. If the cause is fungal, it will require antifungal creams.
It is best to consult a doctor if the dandruff persist or worsens.