Breathing through the nose and feeling breathless may be allergic rhinitis, sinusitis, deviated septum and other reasons. 1. Allergic rhinitis: contact with allergens, causing the nasal mucosa to cause reactive inflammation, resulting in nasal mucosal congestion, edema, increased secretions, blocking the nostrils, so breathing through the nose, feel breathless. 2. Sinusitis: Inflammation of the sinuses, causing local mucous membrane congestion, edema, purulent secretions increase, resulting in blockage of the nostrils, so breathing through the nose, feeling breathless, accompanied by headache, decreased sense of smell and other symptoms. 3. Deviated nasal septum: The structure of nasal septum is deviated to one side or both sides, which leads to the dysfunction of nasal cavity, and symptoms such as nasal congestion, headache and nosebleed can occur. Breathing through the nose and feeling breathless may be due to other reasons, such as nasopharyngeal carcinoma, chronic hypertrophic rhinitis, etc. It is recommended to consult a doctor in time to find out the cause of the disease and standardize the treatment.