When the thin wall between the nasal passages is displaced to one side, it is called a deviated septum. This nasal blockage can lead to a decrease in nasal ventilation and make breathing difficult. Deviated septums can be so severe that they entirely block airflow from one side of the nose.
A septal deviation may be present at birth due to fetal development. More commonly, this condition is caused by trauma or injury to the nose, which caused the septum to be moved to one side.
The natural aging process may worsen a deviation over time, further displacing the septum as the nose grows.