Brittle hair that breaks easily can be caused by nodular brittle hair syndrome, long-term hair coloring or perming, frequent use of hairdryer, malnutrition. 1. Nodular Brittle Hair Disease: Nodular Brittle Hair Disease may be related to heredity, systemic diseases and other factors, manifested as the appearance of nodules in the hair shaft, usually located at the end of the hair, the nodule at the hair is dry, fragile, easy to break. 2. Long-term hair coloring or perming: Long-term hair coloring or perming can damage the keratin and hair follicles of the hair, making the hair fragile and easy to break. 3. Frequent use of hairdryer: frequent use of hairdryer, if the temperature is too high, will cause the loss of hair moisture, but also damage the hair fiber protein, so that the hair appears fragile, easy to break, dry and so on performance. 4. Malnutrition: long-term weight loss, picky eating, partiality, etc., easy to lead to malnutrition, so that the hair is not enough nutrients to supply the normal needs of the hair, thus appearing fragile and easy to break the phenomenon. Hair brittle easy to break may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.