Symptoms caused by a deviated nasal septum vary widely, with some people experiencing predominantly one symptom, while others may have several symptoms simultaneously. The most common symptom is nasal congestion, which can be unilateral or bilateral, depending on the type and degree of the septal deviation. If the deviation affects both sides of the nasal cavity, bilateral congestion occurs; if it affects only one side, unilateral congestion occurs. Another symptom is recurrent nosebleeds, which may be related to a protrusion formed by the deviation, causing the mucous membrane at that location to be thin and prone to erosion and bleeding. Additionally, headaches can occur due to the nasal septum deviation irritating the nasal nerve. Other symptoms include those of secondary conditions such as a runny nose and mouth breathing.