A deviated nasal septum is a crooked septum, which is the structure made of bone and cartilage that divides the nose into two equal parts.

A person who has a deviated nasal septum often has no symptoms or may have a crooked nose, difficulty breathing well through the nose (especially on one side), and a runny nose.

A deviated nasal septum may be caused by injury or surgery to the nose, or by rapid growth, especially at puberty.

A person who has a deviated nasal septum that is not treated may have recurrent nosebleeds and recurrent nasal or sinus infections. If needed, treatment may include medication to treat a runny nose or infection, or surgery to correct the deviation.