Causes Hereditary traits, stress, insufficient rinsing of shampoo, lack of sebum, using a harsh shampoo, vitamin imbalance, pollution, air conditioning and central heating.

• 问题起因：遗传因素，压力，香波未洗净，油脂缺乏，使用强力香波，维生素失调，环境污染，空调与中央供暖设施。