A deviated septum occurs when the thin wall (nasal septum) between your nasal passages is displaced to one side. In many people, the nasal septum is displaced — or deviated — making one nasal passage smaller.
When a deviated septum is severe, it can block one side of your nose and reduce airflow, causing difficulty breathing. The additional exposure of a deviated septum to the drying effect of airflow through the nose may sometimes contribute to crusting or bleeding in certain individuals.
Nasal obstruction can occur from a deviated nasal septum, from swelling of the tissues lining the nose, or from both. Treatment of nasal obstruction may include medications to reduce the swelling or nasal dilators that help open the nasal passages. To correct a deviated septum, surgery is necessary.