A deviated septum is caused by one of three things: you were born with it, you injured your nose, or the cartilage shifted gradually as you aged. Most people have some degree of deviation. An estimated 80 percent of people have a nasal septum that is off-center, though many never notice symptoms.
What the Septum Actually Is
The nasal septum is the thin vertical wall that divides your nose into left and right halves. It’s not a single piece of material. The upper portion is made of bone (a plate from the ethmoid bone above and the vomer bone below), while the front section is flexible cartilage that fills the gap between those bones. This mix of rigid bone and bendable cartilage is part of what makes the septum vulnerable to shifting out of alignment. A “deviated” septum simply means this wall leans to one side, narrowing the airway on that side.
Born With It: Congenital Causes
Many deviated septums begin before or during birth. During pregnancy, sustained pressure from the baby’s own limbs against its face can push the developing septum off-center while still in the womb. But the birthing process itself is the more common culprit. Research comparing babies born vaginally to those born by cesarean section found that anterior septal deviations were significantly more frequent after vaginal delivery, pointing to birth trauma as a major factor.
The mechanics make sense when you consider the anatomy. The distance from the tip of the nose to the back of the skull is one of the longest measurements across a newborn’s head. That makes the nose the most prominent, exposed part of the face as it moves through the birth canal. As the baby’s head rotates during delivery, the canal walls push the soft cartilage to one side. The direction of the shift depends on which way the head turns: a clockwise rotation pushes the cartilage to the right, while counterclockwise pushes it left.
There’s also an evolutionary theory. As humans evolved, the facial skeleton shrank relative to the braincase. The bony frame of the nose may have reduced in size faster than the cartilage inside it, leaving the softer septum slightly too large for its frame and prone to buckling.
Nasal Trauma and Injury
Physical trauma is the most straightforward cause of a deviated septum later in life. The most common sources are accidents, physical altercations, and sports. A blow to the nose typically damages both bone and cartilage at the same time, and a septum that was perfectly centered before the injury can be permanently displaced.
You don’t always need a dramatic fracture for this to happen. A moderate hit during a basketball game, a fall off a bike, or even a car accident where the airbag strikes the face can shift the septum enough to cause noticeable airflow problems. Children are especially susceptible because their nasal cartilage is softer and still developing, so even minor impacts can cause deviations that become more apparent as the nose grows.
Changes From Aging
A septum that was barely off-center at age 20 can become noticeably deviated by age 50. The cartilage in your nose changes over time, losing some of its structural integrity as cellular organization breaks down. Animal research has shown that shifts in the proteins that maintain cartilage stiffness, including changes in how the cartilage processes structural compounds like collagen and elastin, can predispose the septum to bending. In some cases, parts of the septum that were originally rigid hyaline cartilage begin taking on properties of more flexible elastic cartilage, making them more likely to warp.
Normal wear from decades of breathing, combined with the gradual weakening of the cartilage’s internal scaffolding, means a mild deviation you never noticed can slowly worsen into one that blocks airflow or causes recurring sinus problems.
How to Tell If Your Septum Is Deviated
A minor deviation often causes no symptoms at all. When the shift is more significant, the most common sign is difficulty breathing through one nostril, typically worse on one side. Other symptoms include chronic nasal congestion, frequent nosebleeds, facial pain, headaches, snoring, noisy breathing, and reduced sense of smell. A severely deviated septum can make your nose look visibly off-center.
A simple self-check: take a photo of the underside of your nose. If your nostrils are noticeably uneven or different sizes, you may have a deviation. For a formal diagnosis, a provider uses a nasal speculum, a small instrument that gently opens the nostrils, to look at the septum’s position and how it affects the size of each airway. A CT scan or nasal endoscopy can reveal deeper structural details when needed.
When a Deviation Causes Bigger Problems
The narrowed airway from a deviated septum can set off a chain of secondary issues. Blocked drainage pathways make the sinuses more prone to chronic sinusitis and recurring sinus infections. Persistent congestion forces mouth breathing, which dries out the mouth and throat.
The link to sleep apnea is particularly noteworthy. A deviated septum alone doesn’t cause obstructive sleep apnea, but the increased airway resistance and habitual mouth breathing it promotes can encourage the airway to collapse during sleep. One long-term study found that people with deviated septums were more than four times more likely to develop obstructive sleep apnea than those without. In children, a significant deviation can also lead to frequent or long-lasting ear infections.
Treatment Options
Not every deviated septum needs treatment. If yours isn’t causing breathing problems, sleep disruption, or recurring infections, it’s simply an anatomical variation. For mild symptoms, nasal steroid sprays and decongestants can reduce swelling in the nasal passages and improve airflow without addressing the structural issue.
When symptoms meaningfully affect quality of life, such as persistent trouble breathing through the nose, chronic sinus infections, or frequent nosebleeds, surgery called septoplasty is the standard fix. The procedure straightens the septum by repositioning or removing portions of the bone and cartilage. It’s typically an outpatient procedure, meaning you go home the same day. Recovery usually involves a week or two of congestion and tenderness before breathing gradually improves.