The factors of dandruff came from various reasons which are Dryness and oily in the scalp can cause itching that leads to flakes of skin that are white in color fall off in small pieces. The cause of an itchy scalp may be dandruff, which is white or gray visible flakes falling off the head. The hair may be oily but still the flakes of skin keep falling from the head. They can sometimes be as large as a quarter inch and have an oily feel to them. Another symptom of dandruff can be redness in scalp or irritation that does not go away after a simple washing.