Itchy scalp picking down a large piece of something similar to dandruff is a typical symptom of seborrheic dermatitis, mainly related to diet, environment, psychological factors and genetic factors, such as the usual love to eat high-fat, high-sugar food, often eat spicy, irritating food and alcohol abuse. In addition, long-term exposure to humid and hot environments, as well as frequent late nights, poor sleep and other personal irregular habits can cause seborrheic dermatitis to occur. Therefore, patients should pay attention to a reasonable dietary structure, eat more light vegetables and fruits, and pay attention to ensure the quality of sleep, do not stay up late, live a regular life, drink less alcohol, and eat less spicy and stimulating food.