In children, nosebleeds from one nostril may have the following clinical causes: Firstly, some children have deviated nasal septum, and the local protrusion of the septum on the side of the deviation is very obvious, and the stimulation of the back and forth airflow may easily induce local mucosal rupture and bleeding. The second reason is that some children are picky eaters, malnourished or have dry weather, or some patients often have fire, constipation and other triggers, resulting in dryness, erosion and rupture of the mucosa of the nasal cavity, which can easily induce bleeding of the blood vessels under the mucosa. The third reason, some patients recently have allergic rhinitis, nasal vestibular eczema, chronic rhinitis and other manifestations, performance nasal cavity is not ventilated, the nasal cavity is very uncomfortable, the patient often involuntarily pick the nose, touch the nose resulting in artificial damage to the nasal mucosa, resulting in mucosal ulceration, erosion and thus bleeding. All in all, children with nosebleeds from one nostril are better off going to the hospital to be examined by a doctor with a nasal endoscope to see what is the cause of the nasal bleeding.