One side of the nose is not ventilated, which may be caused by deviated nasal septum, foreign body in the nasal cavity, new organisms in the nasal cavity and so on. 1. Deviated nasal septum: Nasal septum is the middle part of two nostrils, when the septum is deviated, it may lead to narrowing of one side of the nasal cavity, so one side of the nose is always out of breath. 2. Nasal foreign bodies: foreign bodies accidentally enter into the nasal cavity, especially in children, which may lead to unilateral nasal congestion, increased secretion and even odor. 3. Nasal neoplasm: one side of the nasal cavity has a maxillary sinus polyp or inverted papilloma, which will lead to one side of the nose is not ventilated. One side of the nose does not breathe, it is recommended to consult a doctor in a timely manner to identify the cause of the disease as soon as possible treatment, so as not to miss the condition.