Nasal blood in only one nostril may be caused by deviated nasal septum, nasal tumor or bad life habits. 1. Deviated septum: If the patient only has blood in one nostril, it may be related to deviated septum. When the nasal septum is curved to one side or partially protruded, the mucous membrane at the convex surface of the deviated septum or at the spines and cristae is more tense and thin, and the surface of the nasal septum is rich in capillaries, so it is easy to have blood in the nasal mucus. 2. Nasal tumor: a small number of patients with blood in nasal discharge unilaterally, accompanied by nasal odor, need to consider whether there are tumors in the nasal cavity, sinuses and other parts of the nasal cavity, and there will be blood in nasal discharge in the early stage of the symptoms. 3. Bad life habits: if you eat spicy food for a long time, irregular work and rest, often digging the nostrils, bad life habits may lead to nasal mucous membrane damage, causing unilateral nasal discharge with blood. The appearance of one nostril with blood in the nose, there may be other reasons, should be timely to the hospital. Improve the relevant examination, standardized treatment.