Nose bleeding in adolescents may be related to dry nasal mucosa, deviated nasal septum, or it may be caused by allergic rhinitis, blood system diseases, nasopharyngeal fibroangioma and other reasons. 1. Dry nasal mucosa, deviated nasal septum: commonly seen in the fall and winter seasons, due to the low humidity of the air, if you do not pay attention to replenish the body with water, resulting in excessive dryness of the nasal mucosa, coupled with a deviated septum, the deviated part of the mucous membrane is relatively thin, it is prone to nosebleed phenomenon. 2. Allergic rhinitis: young people who suffer from allergic rhinitis, due to the presence of inflammatory reaction in the nasal cavity, under the stimulation of inflammatory products, resulting in nasal mucosa congestion, edema, resulting in an increase in the permeability of local blood vessels, it is easy to nose bleed phenomenon, but also can be accompanied by nasal congestion, runny nose and other symptoms. 3. Blood system diseases: due to the coagulation dysfunction, it can cause nose bleeding in adolescents, and the common diseases are thrombocytopenia, leukemia and so on. 4. Nasopharyngeal fibrous hemangioma: this disease occurs more often in adolescent males, manifested by repeated severe nosebleeds. If the nosebleed occurs frequently and repeatedly, and accompanied by other discomforts, the teenager should consult a doctor as soon as possible, after clear diagnosis of the causative factors, and then be guided by the doctor for treatment.