Dry hair can be caused by physiological factors such as too little moisture in the body or improper hair care, or it can also be caused by malnutrition, iron deficiency anemia and other diseases. 1. Physiological factors: Patients may have too little water intake in daily life, or frequent use of alkaline toiletries and frequent hair coloring, perming and other behaviors, which will lead to a decrease in the moisture of the hair, resulting in dry hair phenomenon. 2. Malnutrition: Malnutrition is mainly caused by insufficient nutritional intake, chronic wasting disease or imbalance of nutritional intake ratio, etc., and the patient will have symptoms such as reduction of subcutaneous fat, skin laxity, and dry, fine and yellowish hair, etc. Therefore, the patient will have dry hair. As a result, patients will have dry hair. 3. Iron deficiency anemia:Iron deficiency anemia is due to the imbalance of iron absorption and excretion in the body, the body’s iron content is reduced. The main symptoms of the patient are pale skin, weakness, dry hair easy to fall off, pale nails, etc., so the patient will show dry hair. When the patient has the symptom of dry hair, it may be caused by physiological factors and does not need treatment, pay attention to the frequency of hair coloring and perming. If it is caused by disease, patients should seek medical treatment in time and follow the doctor’s instructions.