Feeling as if only one nostril is working at a time is a common and often puzzling experience. This sensation, where one side of your nose feels clear while the other seems blocked, is a widespread phenomenon. Understanding why this happens involves exploring the nose’s normal physiological processes and various external and medical factors that can influence nasal airflow.
The Nasal Cycle: A Normal Phenomenon
The primary reason one nostril feels more open than the other is the nasal cycle. This natural process involves physiological congestion and decongestion of the nasal cavities, alternating between the two sides. The nasal cycle ensures air is properly warmed, humidified, and filtered before reaching the lungs.
The autonomic nervous system manages this alternating congestion. Its sympathetic and parasympathetic branches regulate blood flow to the erectile tissue, known as turbinates, located inside the nasal passages. These turbinates, which are bony projections covered by specialized tissue, rhythmically swell with blood on one side, causing congestion, while the turbinates on the opposite side decongest, allowing for greater airflow.
A complete nasal cycle typically lasts 2.5 to 4 hours, though it can vary significantly from 30 minutes to over 10 hours depending on the individual and other conditions. This process is usually subtle and goes unnoticed by most people. The nasal cycle also ensures one side of the nose remains moist, which helps maintain the health of the nasal lining and aids in its functions of filtration and humidification.
Everyday Influences on Nasal Airflow
While the nasal cycle is a constant, normal process, several everyday factors can make its effects more noticeable or temporarily alter nasal airflow. One significant influence is sleeping position. Lying on one side can cause the lower nostril to become more congested due to gravity affecting blood flow to the nasal turbinates on that side.
Changes in environmental conditions can also impact how open your nostrils feel. Variations in temperature or humidity, as well as exposure to irritants such as dust, smoke, or strong odors, can lead to increased swelling within the nasal passages, making the natural cycle more apparent. Dry air, particularly in heated indoor environments, can also dry out nasal passages and contribute to a feeling of congestion. These factors do not represent medical conditions but can amplify the sensation of one nostril being more open than the other.
Common Conditions Affecting One Nostril
Beyond the normal nasal cycle and everyday influences, certain medical or anatomical conditions can cause more persistent or severe unilateral nasal blockage. Common infections like the cold or flu lead to inflammation and increased mucus production throughout the nasal passages. The congestion may feel more pronounced in the nostril that is less active in the nasal cycle. Allergic rhinitis, triggered by allergens such as pollen or dust mites, can also cause one-sided swelling and irritation.
Sinusitis, an inflammation of the sinuses, often presents with symptoms that can affect one side more than the other, especially with bacterial infections where pain and pressure might be localized to one side of the face. A deviated septum, where the wall between the nostrils is off-center, is a common anatomical issue that can significantly restrict airflow in one nostril, making it smaller and harder to breathe through. This blockage can be exacerbated during colds or allergies. Nasal polyps, which are non-cancerous growths in the lining of the nose or sinuses, can also block one side of the nose, particularly if they are large or located unilaterally. Unilateral polyps can sometimes be a sign of a tumor, warranting further medical evaluation.
Knowing When to Seek Medical Advice
While an alternatingly blocked nostril is often a normal occurrence, certain situations warrant consulting a medical professional. If unilateral nasal blockage is persistent, severe, or worsening over time, a doctor’s visit is advisable. Symptoms lasting longer than 10 days, especially if accompanied by thick yellow or green mucus, could indicate a bacterial infection requiring treatment.
It is also important to seek medical attention if the blockage is accompanied by pain, fever, vision changes, or facial swelling. Recurrent or unexplained nosebleeds, particularly if they originate from only one side of the nose, warrant evaluation. If the blockage significantly impacts breathing quality, leads to difficulty sleeping, or presents with any other new or concerning symptoms, medical advice should be sought.