Most septal deformities result in no symptoms, and you may not even know you have a deviated septum. Some septal deformities, however, may cause the following signs and symptoms:

• Obstruction of one or both nostrils. This obstruction can make it difficult to breathe through the nostril or nostrils. This may be more noticeable when you have a cold (upper respiratory tract infection) or allergies that can cause your nasal passages to swell and narrow.
• Nosebleeds. The surface of your nasal septum may become dry, increasing your risk of nosebleeds.
• Facial pain. Though there is some debate about the possible nasal causes of facial pain, a severe deviated septum that impacts the inside nasal wall, when on the same side as one-sided facial pain, is sometimes considered a possible cause.
• Noisy breathing during sleep. This can occur in infants and young children with a deviated septum or with swelling of the intranasal tissues.
• Awareness of the nasal cycle. It is normal for the nose to alternate being obstructed on one side, then changing to being obstructed on the other. This is called the nasal cycle. The nasal cycle is a normal phenomenon, but being aware of the nasal cycle is unusual and can be an indication that there is an abnormal amount of nasal obstruction.
• Preference for sleeping on a particular side. Some people may prefer to sleep on a particular side in order to optimize breathing through the nose at night. This can be due to a deviated septum that narrows one nasal passage.

A deviated septum occurs when your nasal septum — the thin wall that separates your right and left nasal passages — is displaced to one side.

A deviated septum can be caused by:

• A condition present at birth. In some cases, a deviated septum occurs during fetal development and is apparent at birth.
• Injury to the nose. A deviated septum can also be the result of an injury that causes the nasal septum to be moved out of position. In infants, such an injury may occur during childbirth. In children and adults, a wide array of accidents may lead to a nose injury and deviated septum — from tripping on a step to colliding with another person on the sidewalk. Trauma to the nose most commonly occurs during contact sports, active play or roughhousing, or automobile accidents.

The normal aging process may affect nasal structures, worsening a deviated septum over time. Also, changes in the amount of swelling of nasal tissues, because of developing rhinitis or rhinosinusitis, can accentuate the narrowing of a nasal passage from a deviated septum, resulting in nasal obstruction.

For some people, a deviated septum is present at birth — occurring during fetal development or due to injury during childbirth. After birth, a deviated septum is most commonly caused by an injury that moves your nasal septum out of place. Risk factors include:

• Playing contact sports
• Not wearing your seat belt while riding in a motorized vehicle

If you have a severely deviated septum causing nasal obstruction, it can lead to:

• Dry mouth, due to chronic mouth breathing
• A feeling of pressure or congestion in your nasal passages
• Disturbed sleep, due to the unpleasantness of not being able to breathe comfortably through the nose at night