It is common to notice that one nostril appears to be a different size, shape, or allows for easier breathing than the other. The difference in how air moves through your nose is often due to a dynamic, temporary process, while any fixed visual disparity results from the same underlying principle that makes all human features slightly unique.
Is Asymmetry Normal
The human body, including the face and nose, is not built with perfect bilateral symmetry. A slight degree of difference between the left and right sides is the biological norm, not the exception. Minor variations in the size, shape, and placement of features like the eyes, ears, and nostrils are inherent to human development and genetics.
This natural asymmetry means the cartilage and soft tissue forming the nostrils, known as the alae, can be slightly unequal in their flare or position. Such subtle differences are present in nearly everyone and are generally not a cause for concern unless they significantly impede a physical function.
The Nasal Cycle
The most frequent reason people perceive a temporary difference in how their nostrils function is a phenomenon called the nasal cycle. This is an automatic, subconscious process regulated by the autonomic nervous system, which alternates the primary airflow between the left and right nasal passages. The cycle involves the swelling and shrinking of structures called turbinates, which are ridges of bone covered in a layer of tissue containing erectile cells.
At any given time, the turbinates in one nostril become congested with blood, causing the passage to narrow and reducing airflow on that side. Simultaneously, the turbinates in the opposite nostril decongest, opening that passage to become the dominant airway. This process alternates, with one side remaining congested for a period that typically ranges from two to six hours before the other side takes over. The cycle ensures that one side of the nose is always partially rested and moist, which is necessary for warming, humidifying, and filtering the air you breathe.
Structural Causes for Size Differences
While the nasal cycle accounts for temporary functional differences, more fixed or permanent asymmetry is usually caused by the nasal septum. The septum is the wall of cartilage and bone that divides the nose into two separate chambers. It is estimated that a vast majority of the population, often between 75 and 90 percent, has some degree of nasal septum deviation (DNS).
A deviated septum means this dividing wall is off-center, causing one nasal passage to be significantly narrower than the other. This deviation can occur during development, due to genetic factors, or as a result of trauma, such as an injury sustained during childhood or sports. When the internal space is smaller due to this deviation, the nostril opening on the affected side may appear smaller or less functional, leading to chronic difficulty breathing out of that side. Other structural causes can include the shape of the alar cartilages, which form the nostril rims, or scar tissue from a previous injury or surgery.
When to Seek Medical Advice
In most instances, a minor difference in nostril size or alternating airflow does not require medical attention. However, there are specific symptoms that suggest the asymmetry is causing a health issue and warrant a consultation with a healthcare provider. These red flags include persistent and severe difficulty breathing that does not alternate between sides or significantly interferes with sleep and daily activities.
You should also seek medical advice if the asymmetry or blockage is accompanied by frequent, unexplained nosebleeds, chronic facial pain, or signs of a persistent infection. If a noticeable asymmetry, perhaps resulting from a broken nose, appeared suddenly or is worsening over time, an evaluation can help determine if a structural correction is necessary to restore proper function.