Experiencing difficulty breathing through one nostril is a common sensation. This uneven airflow, where one side feels clear while the other is blocked, can lead to a feeling of congestion.
The Nasal Cycle
The alternating blockage of nostrils is a normal bodily function called the nasal cycle. This physiological process involves blood vessels in the nasal passages cyclically swelling and constricting; as one side becomes congested from increased blood flow, the other simultaneously decongests, allowing open airflow. This autonomic nervous system-regulated alternation typically switches every few hours, though duration varies. While often unnoticed, the cycle can become more apparent when lying down, as blood flow contributes to congestion in the dependent nostril. This cycle ensures one side of the nose remains moist, aiding in humidifying and filtering air.
Common Temporary Causes
Beyond the normal nasal cycle, several temporary factors can cause one-sided nasal blockage. During a common cold (viral rhinitis), inflammation and increased mucus can cause congestion. Allergic rhinitis, triggered by allergens like pollen, prompts an immune response resulting in tissue swelling and excess mucus. Sinus infections (sinusitis) can cause inflammation and fluid buildup, leading to localized pressure and blockage.
Environmental irritants also contribute to temporary nasal blockage by causing irritation and swelling. Exposure to smoke, strong odors, air pollution, or dry air can trigger a temporary inflammatory response. Blockage from colds or allergies is often more pronounced in the nostril already in its congested nasal cycle phase. These causes are acute and often resolve with time or over-the-counter remedies.
Underlying Conditions and Structural Issues
Persistent or chronic one-sided nasal blockage can stem from underlying conditions or structural irregularities. A deviated septum, where the thin wall separating nostrils is off-center, can restrict airflow in one passage. This deviation makes one side smaller, intensifying blockage, especially with colds or allergies. Nasal polyps are non-cancerous, soft growths in the nasal passages or sinuses; larger polyps can physically obstruct airflow.
Turbinate hypertrophy, the enlargement of bony structures inside the nose that regulate airflow, is another structural issue. Chronically swollen turbinates, often due to allergies, irritants, or infection, can cause persistent blockage. In children, a foreign object in a nostril can suddenly cause unilateral blockage, sometimes with foul-smelling or bloody discharge.
When to Seek Medical Advice
While a temporarily blocked nostril is often harmless, consult a healthcare professional if the blockage is persistent or worsens, lasting over 10 days, or significantly impacts daily activities like sleep or sense of smell. Symptoms such as severe facial pain, high fever, facial swelling, or vision changes warrant immediate medical attention.
Consistent nosebleeds, especially after a head injury, should prompt a doctor’s visit. For infants or young children, any new one-sided blockage should be evaluated to rule out a foreign object.