Seborrheic dermatitis (dandruff) is an inflammatory skin condition which causes the formation of yellowish or white scales in fatty areas such as the scalp, inside the ear and face.
A dermatologist is a doctor who specializes in diseases of the skin, hair, nails and mucous membranes.
An allergist is a doctor who specializes in the prevention, diagnosis and treatment of allergies.
A doctor or family doctor is responsible for diagnosing and prescribing medical treatments to patients. The family doctor refers to patients where a specialist when a specific treatment is required.
Remember that for the proper selection of health professional that treats seborrheic dermatitis (dandruff) you must consider the nature, severity and symptoms you are presenting.