Suddenly dry, rough and flaky skin can be caused by eczema, fungal infections, contact dermatitis and other reasons. 1. Eczema: internal and external stimulation of a variety of factors causing inflammatory skin reactions, chronic eczema can cause skin mossy changes, itchy skin may lead to the phenomenon of suddenly dry rough skin. 2. Fungal infections: Fungal infections caused by localized dermatophytosis may also cause sudden dryness and roughness of the skin. There may also be accompanied by skin erythema, flaking and so on. 3. Contact dermatitis: allergy caused by skin contact with external sensitizers. It is also possible to cause localized sudden dry skin phenomenon. Sudden dry skin, there may be other reasons, need to go to the hospital in time to check, clear cause for treatment.