The cause of dry hair may actually be caused by a variety of factors, generally the most common may be due to malnutrition of the patient, resulting in a lack of local nutrition of the hair and hair follicles in the scalp area, thus causing dry hair. It may also be due to other disease factors that recur over a long period of time, causing nutritional disorders in the scalp area, so that the symptoms of dry hair are formed. In addition, there are also infection factors, especially in the scalp area, such as the common scalp pityriasis or scalp allergic diseases, such as seborrheic dermatitis, which can also cause dry hair. In particular, dry seborrheic dermatitis is not only dry, but may also have varying degrees of scaling.