Frequent bleeding from the left nostril, i.e., unilateral nosebleeds, common causes include frequent nose picking, dry environment, rhinitis, sinusitis, nasal sinus and nasopharyngeal tumors or polyps, deviated septum on the left side of the nose and other diseases. It is recommended to go to the ear, nose and throat department of the hospital to clarify the cause of the disease after diagnosis and treatment. 1. Frequent nose picking, nasal mucosa dryness, etc., easy to cause nasal mucosa capillary rupture, can cause frequent bleeding from the left nostril. 2. Patients with rhinitis and sinusitis, nasal mucosa congestion and edema, more nasal mucus, often blowing the nose with force, can cause nasal mucosal capillary rupture, can cause bleeding from the left nostril. 3. Nasal sinus and nasopharyngeal tumors or polyps, such as benign tumors, fibrous hemangiomas and malignant tumors, can cause repeated bleeding from the left nostril. 4. A deviated septum on the left side can also cause recurrent bleeding from the left nostril. Frequent bleeding from the left nostril can also be seen in other causes, such as hematologic disorders, increased arterial and venous pressure, nutritional disorders or vitamin deficiencies and other diseases. If the symptoms of frequent bleeding from the nostril appear, it is recommended to go to the hospital as soon as possible to avoid delaying the condition.