The causes of teenage hair loss mainly include the following reasons: 1, malnutrition: related to micronutrient deficiency, hair nutrient deficiency, blood loss, etc. With the improvement of living standards, malnutrition hair loss has become rare; 2, excess nutrition: obese teenagers can secrete too much oil, leading to the phenomenon of seborrheic alopecia; 3, excessive stress: teenagers due to excessive study pressure can lead to kidney deficiency, qi and blood deficiency, thus causing the phenomenon of hair loss.