Difficulty breathing through the nose is a common experience. The nose acts as the body’s natural air conditioning system, warming, humidifying, and filtering inhaled air before it reaches the lungs. When nasal passages are obstructed, this essential conditioning process is bypassed, forcing a switch to mouth breathing that can negatively impact sleep and respiratory health.
Acute Causes: Infections and Temporary Swelling
The most frequent cause of sudden nasal blockage is an acute infection, such as the common cold or influenza. Congestion is primarily caused by an inflammatory response to the invading virus, not just excess mucus. The body releases chemical mediators that cause blood vessels lining the nasal passages to dilate, leading to rapid tissue swelling, known as mucosal edema.
This temporary swelling dramatically narrows the airway. The increased blood flow brings immune cells to the site of infection and the resulting warmth may help inhibit viral replication. While uncomfortable, this type of congestion is typically self-limiting and resolves within seven to ten days as the body clears the infection.
Chronic Inflammation: Allergies and Non-Allergic Rhinitis
Congestion persisting for weeks or months often results from chronic inflammation, typically due to rhinitis. Allergic rhinitis, or hay fever, involves an immune system overreaction to harmless environmental triggers like pollen or pet dander. Exposure to these allergens causes the immune system to produce IgE antibodies, triggering the release of histamine. This cascade leads to prolonged swelling of the nasal lining, often accompanied by sneezing and itching.
Non-allergic rhinitis, also called vasomotor rhinitis, presents with similar congestion but is not immune-mediated. The swelling is caused by hyper-responsive blood vessels in the nasal lining that dilate excessively in response to non-allergic factors. Common triggers include sudden changes in temperature, strong odors, perfume, or spicy foods.
Structural and Physical Obstructions
If persistent congestion does not respond well to anti-inflammatory medications, the cause may be a physical or anatomical blockage. The nasal septum, the wall separating the nasal passages, can be off-center, a condition called a deviated septum. This deviation physically narrows the airway, often resulting from prior trauma.
Another primary obstruction involves the turbinates, which are scroll-shaped structures inside the nose. These can become chronically enlarged, known as turbinate hypertrophy, due to long-standing inflammation or as compensation for a deviated septum.
Nasal polyps are soft, non-cancerous growths that develop from the lining due to chronic inflammation. As these growths enlarge, they physically obstruct the air passage and often reduce the sense of smell. These structural issues frequently require physical correction, such as surgery, to restore normal airflow.
Rebound Congestion from Nasal Spray Misuse
A self-induced cause of persistent nasal blockage is Rhinitis Medicamentosa, or rebound congestion. This condition results from the prolonged use of topical decongestant nasal sprays, such as those containing oxymetazoline. These sprays work by forcing blood vessels in the nasal lining to constrict, rapidly shrinking swollen tissue and opening the airway.
The nasal tissue quickly adapts to the medication’s effect. When the drug wears off, the vessels “rebound” by dilating even more severely than before, causing worse congestion. This creates a cycle where the user must spray more frequently, leading to dependency and chronic swelling.
To prevent this rebound effect, healthcare providers caution against using these sprays for more than three to five consecutive days. If congestion persists or worsens after discontinuing the spray, consulting a medical professional is necessary to identify the underlying cause.