When it comes to hair loss and hair fall, I believe many people think of Prince William of England. So why does hair loss and hair fall happen? Is hair loss and hair fall a disease? In fact, hair loss, hair fall does not necessarily mean that there is a disease, all people will experience hair loss, hair fall, hair growth is fastest at the age of 15-30 years, generally women’s hair growth is more slow than men’s, while women’s hair is more than men’s. The hair growth cycle includes the anagen phase, regression phase, and resting phase, and about 80% of hair is in the anagen phase. Hair growth peaks in March and is lowest in September. Daily hair loss is about 60 roots, usually not more than 100 roots, and about the same amount of hair regrowth; so if the daily hair loss is less than 100 roots and the overall hair volume is not significantly abnormal, it is a normal phenomenon and there is no need to be nervous. Of course, if the overall hair volume is significantly abnormal, then you need to go to the hospital to clarify the type of hair loss and the triggering factors. General hair loss includes two major categories: physiological hair loss and pathological hair loss. Physiological alopecia: resting alopecia is common, such as infant alopecia, senile alopecia, postpartum alopecia; it may be related to factors such as childbirth, malnutrition, high fever, surgery, blood loss, and severe mental factors; pathological alopecia: mainly includes androgenic alopecia, patchy baldness, scarring alopecia and so on. For example, alopecia areata may be related to abnormal immune function, neuropsychiatric factors, sleep disorders, endocrine disorders; androgenic alopecia is related to elevated androgen levels, high expression of androgen receptors in hair follicles in the alopecia area; anagen alopecia is related to the application of cytotoxic drugs; scarring alopecia is related to damage by physical and chemical factors, infections (such as tinea capitis, folliculitis), certain skin diseases (skin tumors, lupus erythematosus, lichen planus) etc. Of course, certain substance deficiencies may also cause hair loss. For example, deficiency of zinc, calcium, vitamin D, iron, essential fatty acids, biotin, protein, essential amino acids, B vitamins, etc. can cause hair loss and hair fall.