Nosebleeds in 15 year old children may be caused by nasal dryness, acute rhinitis, blood disorders and so on. 1. Nasal dryness: when the air is dry and 15-year-old children drink too little water, it will easily lead to nasal mucosa dryness, causing damage to the mucosa inside the nose, resulting in nosebleeds. 2. Acute rhinitis: when a 15-year-old child suffers from acute rhinitis, it will easily lead to congestion and swelling of the nasal mucosa, bloody nasal discharge, nosebleeds, and also accompanied by nasal congestion, nasal itching and other symptoms. 3. Blood diseases: If a 15-year-old child suffers from leukemia, thrombocytopenic purpura and other blood diseases, due to platelet abnormalities, it may lead to nosebleeds, accompanied by symptoms such as pallor and fatigue. 15-year-old children with nosebleeds, may also be nasopharyngeal fibrous hemangioma, etc., parents should take their children to the hospital in a timely manner, improve the examination to clarify the cause of the disease, and follow the doctor’s instructions for treatment.