The causes of long-term nasal blockage may include chronic hypertrophic rhinitis, deviated nasal septum, nasal polyps and nasal tumors. 1. Chronic hypertrophic rhinitis: it will cause hyperplasia of the nasal mucosa and viscous secretion, resulting in nasal congestion on one side and ventilation on the other. 2. Deviated nasal septum: the nasal septum is deviated to one side, and there is a protrusion in the local area, which will cause nasal dysfunction, and there will be a situation that the nose is blocked on one side for a long time. 3. Nasal polyps: benign swelling formed from the proliferated mucosa of the nasal passages protruding into the nasal cavity. If nasal polyps appear on one side of the nose, it will cause symptoms of nasal congestion on the affected side. 4. Nasal tumors: Nasopharyngeal fibrous hemangioma, inverted papilloma and other nasal tumors can cause unilateral nasal congestion. There are many reasons why nasal congestion persists for a long period of time, and it is recommended to consult a doctor for a clear diagnosis in order to avoid delaying the condition.